JP2013207134A - Bulk rh diffusion source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bulk RH diffusion source that reduces the consumption of the heavy rare earth element RH by increasing a throughput per unit volume during heating, and can reduce manufacturing cost for implementation of a mass-production scale by reusing a heavy rare earth element RH without using large-scale facilities nor new facilities, in a manufacturing method of improving Hof an R-T-B-based sintered magnet by supplying and diffusing the heavy rare earth element RH.SOLUTION: A composition formula in mass% representation is expressed by RHRLFeM, where RH is Dy, RL is Nd and/or Pr, and M is Co and/or Al, and contents consist of 45 mass%≤a≤75 mass%, 0 mass%≤b≤20 mass%, 25 mass%≤c≤55 mass%, 0 mass%≤d≤15 mass%, and inevitable impurities for the rest.

Description

The present invention relates to a bulk RH diffusion source used for supplying and diffusing heavy rare earth elements RH in a manufacturing method for improving _HcJ of an _RTB -based sintered magnet by supplying and diffusing heavy rare earth elements RH.

  R-T-B sintered magnets (R is at least one of rare earth elements and always contains Nd, T is at least one of transition metal elements and always contains Fe), and is the highest among permanent magnets. It is known as a high performance magnet and is used in various motors such as a voice coil motor (VCM) of a hard disk drive, a motor for an electric vehicle, a motor for a hybrid vehicle, and home appliances.

The RTB-based sintered magnet is composed of a main phase made of a compound having an R ₂ T ₁₄ B-type crystal structure and a grain boundary phase located at the grain boundary portion of the main phase. The main phase R ₂ T ₁₄ B phase is a ferromagnetic phase and mainly contributes to the magnetization action of the R-T-B system sintered magnet.

In the R-T-B based sintered magnet, a part of the light rare earth element RL (mainly Nd and / or Pr) contained in R in the main phase R ₂ T ₁₄ B phase is converted to heavy rare earth element RH (mainly Dy And / or Tb) is known to improve the coercive force H _cJ (hereinafter simply referred to as “H _cJ ”). That is, in order to improve _HcJ , it is necessary to use a lot of heavy rare earth elements RH.

However, in the R-T-B based sintered magnet, when the light rare earth element RL in the R ₂ T ₁₄ B phase is replaced with the heavy rare earth element RH, H _cJ is improved, while the residual magnetic flux density B _r (hereinafter simply referred to as “ _rear magnetic flux element B _r ”). “B _r ”) decreases. Therefore, the use of RH less heavy rare-earth element, is possible to improve the H _cJ are sought without reducing the B _r. Moreover, since the heavy rare earth element RH is a rare metal, a reduction in the amount of use is desired.

As a means for improving the _{HcJ of an RTB} -based sintered magnet, a metal, an alloy, a compound, or the like containing a heavy rare earth element RH is supplied to the sintered magnet by a specific means, and the heavy rare earth element RH is then subjected to heat treatment. is diffused inside the magnet, by replacing the light rare-earth element RL in the R 2 _T 14 _B Aisotokara portion in the heavy rare-earth element RH, a method of improving the H _cJ while suppressing a decrease in B _r is proposed Yes.

  Patent Document 1 arranges an RTB-based sintered magnet body and an RH bulk body containing a heavy rare earth element RH (at least one selected from the group consisting of Dy, Ho, and Tb) at an interval. In addition, a method is disclosed in which the heavy rare earth element RH is diffused into the sintered magnet body while the heavy rare earth element RH is supplied from the bulk body to the surface of the sintered magnet body by heating them.

  Patent Document 2 discloses that a sintered body of a rare earth magnet is immersed in a slurry in which particles of an iron compound of Dy or Tb are dispersed and applied to the slurry, and then heat treatment is performed to diffuse Dy or Tb into the sintered body. Discloses a method of making them.

  In Patent Document 3, the RTB-based sintered magnet body and the RH diffusion source are loaded into the processing chamber so as to be relatively movable and close to or in contact with each other, and are moved continuously or intermittently within the processing chamber. Discloses a method of simultaneously supplying the heavy rare earth element RH and diffusing into the sintered magnet body by performing heat treatment.

International Publication No. 2007/102391 JP 2009-289994 A International Publication No. 2011/007758

In the method of Patent Document 1, while supplying a heavy rare earth element RH to the surface of the sintered magnet body while keeping the growth rate of the RH film formed on the surface of the RTB-based sintered magnet body low, Since the temperature of the sintered magnet body is maintained at a level suitable for diffusion, the heavy rare earth element RH flying on the surface of the sintered magnet body quickly penetrates into the sintered magnet body due to grain boundary diffusion. Therefore, grain boundary diffusion occurs preferentially over the diffusion into R ₂ T ₁₄ B crystal grains (intragranular diffusion), and the coercive force can be improved while suppressing a decrease in residual magnetic flux density.

  However, the method of Patent Document 1 uses Dy metal (Dy with a purity of 99.9%) that is easily welded to the R-T-B system sintered magnet body as the RH bulk body. In order to prevent welding between the sintered magnet body and the RH bulk body, the RTB-based sintered magnet body and the RH bulk body are arranged with a space therebetween. Therefore, the amount of processing per unit volume cannot be increased during heating. That is, there is a problem that a large amount of RTB-based sintered magnet bodies cannot be heat-treated at once.

  Further, the method of Patent Document 1 has the following problems. FIG. 7 is an explanatory view showing an arrangement form of the RH bulk body and the sintered magnet body in the method of Patent Document 1. In the method of Patent Document 1, in order to dispose the RTB-based sintered magnet body 11 and the RH bulk body 12 at an interval in the processing chamber 13, a holding member (for example, a net made of Nb) 14 is used. And the spacer 15 is necessary. Since the heavy rare earth element RH supplied from the RH bulk body 12 to the surface of the RTB-based sintered magnet body 11 also adheres to the holding member 14 and the spacer 15, the RTB-based sintered magnet body accordingly. 11 The amount of heavy rare earth element RH supplied to the surface decreases. Therefore, it is necessary to supply the heavy rare earth element RH more than the amount adhering to the holding member 14 and the spacer 15, and there is a problem that the amount of heavy rare earth element RH that is a rare metal increases.

In the method of Patent Document 1, the RH bulk body can be reused. However, since it is necessary to increase the supply amount of the heavy rare earth element RH as described above, the volume of the RH bulk body becomes small after several uses, and accordingly, the supply amount of the heavy rare earth element RH varies and is obtained. Variation occurs in H _cJ of the _RTB -based sintered magnet. For repeated reuse, the volume of the RH bulk body may be increased, but there is a problem that the amount of treatment per unit volume is increasingly reduced.

  In the method of Patent Document 2, it is necessary to apply a slurry in which a particulate compound such as DyFe or TbFe is dispersed to a sintered body, so new equipment such as a coating device and a drying device is required. There is a problem that the manufacturing cost increases. In the method of Patent Document 2, there is no idea of reusing the compound because the compound itself such as DyFe and TbFe is diffused in the sintered body.

Further, in the method of Patent Document 2, the applied DyFe and TbFe are diffused into the sintered body all at once by the heat treatment after the application, so that intragranular diffusion occurs in the surface area of the magnet body along with the grain boundary diffusion. To improve _{H cJ} in the R-T-B based sintered magnet while suppressing a decrease in _{B r} is by replacing a light rare earth element _R 2 _{T 14} B Aisotokara unit Dy or Tb by grain boundary diffusion What is necessary is just to replace the central portion of the R ₂ T ₁₄ B phase. When substitution is performed up to the center of the R ₂ T ₁₄ B phase, _Br is lowered. Therefore, the occurrence of intragranular diffusion means that Dy and Tb are wasted. That is, in Patent Document 2, extra Dy and Tb are used for the amount consumed for intragranular diffusion.

  The method of Patent Document 3 requires a continuous or intermittent movement of an RH diffusion source composed of an RTB-based sintered magnet body and a Dy cut wire or small pieces charged in the processing chamber, which is large-scale. This requires a large amount of equipment and increases the manufacturing cost. In Patent Document 3, since the RH diffusion source is constantly moving in the processing chamber, welding with the sintered magnet body is suppressed. Therefore, the RH diffusion source can be reused. However, in order to reuse the RH diffusion source, the sintered magnet body and the RH diffusion source must be separated, and a new facility or a new process is required for the separation and recovery process, which increases the manufacturing cost. There is a problem of inviting.

The present invention relates to a process per unit volume at the time of heating in a production method disclosed in the prior art document and the like, which improves _HcJ of an _RTB -based sintered magnet by supplying and diffusing heavy rare earth elements RH. the amount increases, reducing the amount of heavy rare-earth element RH as to suppress a decrease in B _r, without using any large-scale equipment and new equipment, by reusing repeated heavy rare-earth element RH, mass production scale An object of the present invention is to provide a bulk RH diffusion source capable of reducing the manufacturing cost.

The RTB-based sintered magnet of the present invention according to claim 1, wherein R is at least one rare earth element and necessarily contains Nd, and T is at least one transition metal element and always contains Fe. The bulk RH diffusion source for manufacturing is
The composition formula in mass% notation is represented by RH _ab RL _b Fe _cd M _d ,
RH is Dy, RL is Nd and / or Pr, M is Co and / or Al,
45% by mass ≦ a ≦ 75% by mass,
0% by mass ≦ b ≦ 20% by mass,
25% by mass ≦ c ≦ 55% by mass,
0% by mass ≦ d ≦ 15% by mass,
And inevitable impurities.

The present invention according to claim 2 is the bulk RH diffusion source according to claim 1, wherein the bulk RH diffusion source is any one of a sintered alloy, a cast alloy, and a roll quenched alloy.
A third aspect of the present invention is the bulk RH diffusion source according to the second aspect, wherein the bulk RH diffusion source is a sintered alloy.
According to a fourth aspect of the present invention, in the bulk RH diffusion source according to the third aspect, the sintered alloy is obtained by pulverizing, forming, and sintering a cast alloy or a roll quenched alloy.
The present invention according to claim 5 is the bulk RH diffusion source according to any one of claims 1 to 4, wherein 5 mass% ≦ b ≦ 20 mass%.
A sixth aspect of the present invention is the bulk RH diffusion source according to any one of the first to fifth aspects, wherein RL is Nd.
The present invention according to claim 7 is the bulk RH diffusion source according to any one of claims 1 to 6, wherein 5 mass% ≦ d ≦ 15 mass%.
The present invention according to claim 8 is the bulk RH diffusion source according to claim 7, wherein RL is Nd, M is Co, and a (DyNd) ₃ Co compound phase and a (DyNd) (FeCo) ₂ compound phase ( All of the chemical formulas contain a molar ratio).
The present invention according to claim 9 is the bulk RH diffusion source according to claim 7, wherein RL is Nd, M is Al, (DyNd) ₃ Al compound phase and / or (DyNd) ₂ Al, It is characterized by containing a DyNd) FeAl compound phase (all of the above chemical formulas are expressed in molar ratios).
A tenth aspect of the present invention is the bulk RH diffusion source according to any one of the first to ninth aspects, wherein the thickness is not less than 0.3 mm and not more than 5 mm.

According to the first aspect of the present invention, since the RH diffusion source is bulk and the contents of RH and Fe are in a specific range, it is difficult to weld to the RTB-based sintered magnet. ing. Therefore, in the manufacturing method for improving the _HcJ of the _RTB -based sintered magnet by supplying and diffusing the heavy rare earth element RH, the RTB-based sintered magnet material and the bulk RH diffusion source are spaced apart. Without being adjacent to each other, and the amount of processing per unit volume during heating can be increased.

Further, the bulk RH diffusion source has a lower content of RH than the heavy rare earth element RH disclosed in the above-mentioned patent documents and the like, and even if it is arranged adjacent to each other without a gap, the bulk RH diffusion source has an RTB. RH is not excessively supplied to the sintered magnet material. Therefore, it is possible to prevent intragranular diffusion from occurring in the surface layer region of the RTB-based sintered magnet material. This makes it possible to reduce the amount of RH is a rare metal it is possible to suppress a decrease in B _r.

  In addition, since the RTB-based sintered magnet material and the bulk RH diffusion source can be arranged adjacent to each other without a gap, a holding member, a spacer, or the like is not necessary. As a result, it is not necessary to supply extra RH as much as it adheres to the holding member or spacer, and RH can be efficiently supplied from the bulk RH diffusion source to the RTB-based sintered magnet material. The amount of metal RH used can be reduced.

  In addition, RH can be supplied and diffused at the same time just by heating the adjacent R-T-B sintered magnet material and bulk RH diffusion source under a specific atmosphere. This eliminates the need for use and simplifies the manufacturing process and reduces the number of manufacturing steps. Further, since the bulk RH diffusion source is prevented from welding with the R-T-B system sintered magnet, it can be reused. Therefore, by using the bulk RH diffusion source according to the present invention as set forth in claim 1, it is possible to reduce the manufacturing cost in the mass production scale.

According to this invention of Claim 2, since the process which prepares a bulk RH diffusion source can be implemented with an existing installation, manufacturing cost can further be reduced.
According to the third aspect of the present invention, since it is not necessary to perform grinding work and no processing waste is generated, the processing cost can be reduced and the RH contained in the processing waste is not wasted, and the use of RH The amount can be reduced. Moreover, since it can prepare with the existing equipment, manufacturing cost can be reduced further. Moreover, manufacturing cost can be further reduced by using the metal mold | die used at the process of preparing the RTB type | system | group sintered magnet raw material which performs an RH supply diffusion process as a metal mold | die at the time of shaping | molding. Further, the thickness can be easily adjusted, and a relatively thin one can be easily prepared. Also, a plurality of bulk RH diffusion sources having the same shape and the same thickness and excellent dimensional accuracy can be easily prepared.
According to the fourth aspect of the present invention, it is possible to utilize a cast alloy or a roll quenching alloy having a size and shape that cannot be used as a bulk RH diffusion source as it is, and the manufacturing cost can be further reduced.
According to the present invention described in claim 5, even if the bulk RH diffusion source is repeatedly reused, a stable _HcJ improvement effect can be obtained in the R-T-B sintered magnet after the RH supply diffusion treatment. it can.
According to this invention of Claim 6, since the raw material used at the process of preparing a RTB system sintered magnet raw material can be diverted, the procurement cost of a raw material, etc. can be reduced.
According to the present invention as set forth in claim 7, a stable quality _RTB -based sintered magnet is produced in which there is almost no change in _HcJ even if the number of times the bulk RH diffusion source is repeatedly reused is increased. can do.
According to the eighth and ninth aspects of the present invention, the RH content near the surface of the bulk RH diffusion source is suppressed from gradually decreasing, and the internal structure of the bulk RH diffusion source is homogenized. The As a result, even if the bulk RH diffusion source is repeatedly reused, a certain amount of RH can be supplied to the _RTB -based sintered magnet material regardless of the number of repetitions, and a stable _HcJ improvement effect can be achieved. Can be obtained.
According to the tenth aspect of the present invention, the throughput per unit volume during heating can be further increased.

It is explanatory drawing which shows an example of the arrangement | positioning form of a RTB type sintered magnet raw material and a bulk RH diffusion source. It is explanatory drawing which shows an example of a processing case. It is explanatory drawing which shows an example of the arrangement | positioning form of the RTB type sintered magnet raw material and bulk RH diffusion source using a processing case. It is explanatory drawing which shows an example of the arrangement | positioning form of the bulk RH diffusion source in a process case. It is a figure which shows the X-ray-diffraction pattern of a bulk RH diffusion source. It is a photograph which shows the reflected electron image by FE-SEM of a bulk RH diffusion source. It is explanatory drawing which shows the arrangement | positioning form of the RH bulk body and sintered magnet body in the method of patent document 1. FIG.

The bulk RH diffusion source of the present invention is used in a manufacturing method disclosed in the prior art document and the like for improving the _HcJ of an _RTB -based sintered magnet by supplying and diffusing heavy rare earth elements RH. For example, after an RTB-based sintered magnet material and a bulk RH diffusion source according to the present invention are disposed adjacent to each other in a furnace such as a general heat treatment furnace, the temperature is 800 ° C. or higher in a reduced pressure atmosphere of 50 Pa or lower. By heating to a temperature of 1000 ° C. or less, RH in the bulk RH diffusion source is vaporized, and the RH is supplied to the surface of the R-T-B system sintered magnet material, while the RH is R-T-B system. can be diffused inside the sintered magnet material, it is possible to improve the H _cJ while suppressing a decrease in B _r of the R-T-B-based sintered magnet.

  In the description of the present invention, the RH in the bulk RH diffusion source is vaporized, and the RH is supplied to the surface of the R-T-B system sintered magnet material, while the RH is supplied to the R-T-B system sintered magnet material. The diffusion inside is referred to as “RH supply diffusion processing”. In addition, after performing the RH supply diffusion process, RH is diffused into the R-T-B system sintered magnet material without supplying the RH, which is referred to as “RH diffusion process”. Furthermore, the heat treatment performed for the purpose of improving the magnet characteristics of the RTB-based sintered magnet after the RH supply diffusion treatment or after the RH diffusion treatment is simply referred to as “heat treatment”.

  In the description of the present invention, the RTB-based sintered magnet before the RH supply diffusion treatment is referred to as an “RTB-based sintered magnet material”, and the RTB after the RH supply diffusion treatment. The system sintered magnet is referred to as “R-T-B system sintered magnet”.

The bulk RH diffusion source of the present invention is:
The composition formula in mass% notation is represented by RH _ab RL _b Fe _cd M _d ,
RH is Dy, RL is Nd and / or Pr, M is Co and / or Al,
45% by mass ≦ a ≦ 75% by mass,
0% by mass ≦ b ≦ 20% by mass,
25% by mass ≦ c ≦ 55% by mass,
0% by mass ≦ d ≦ 15% by mass,
And inevitable impurities.

  In the following description, “(mass%)” is displayed after the composition formula when the composition formula is expressed by mass%, and “(molar ratio)” is displayed after the chemical formula when the chemical formula is expressed by molar ratio. Is displayed.

  RH is Dy. In the composition formula (mass%), the content of RH is represented by ab, and the value of a is 45 mass% or more and 75 mass% or less. The value of b is the content of RL (RL is Nd and / or Pr) and is 0% by mass or more and 20% by mass or less. That is, a part of RH (Dy) can be replaced with RL (Nd and / or Pr). The reason for limiting a, which is the content of RH, will be described below. In order to make the description easy to understand, a case where the value of b is 0% by mass (without RL substitution) will be described, and the reason for limiting b will be described later. In addition, when the content of Fe is c (the value of d is 0% by mass = no substitution of M), the lower limit of a and the upper limit of c and the reasons for limiting the upper limit of a and the lower limit of c are the same. c is written in parentheses, and explanation of the reason for limitation of c is omitted. In addition, RH may be expressed as Dy only for the following explanation of the reason for limitation.

  When the value of a (content of RH) is less than 45% by mass (when the value of c (content of Fe) exceeds 55% by mass), the amount of RH supplied to the RTB-based sintered magnet material is This is not preferable because it decreases and requires time for the RH supply diffusion treatment. On the other hand, if the value of a exceeds 75% by mass (if the value of c is less than 25% by mass), the possibility of welding with the RTB-based sintered magnet increases, and RTB-based sintering is achieved. Since RH is excessively supplied to the surface of the magnet material and there is a risk of intragranular diffusion, it is not preferable. Further, if the value of a is 45% by mass or more (the value of c is less than 55% by mass), by adjusting the conditions (atmosphere and temperature) of the RH supply diffusion treatment, the RTB-based sintered magnet The amount of RH supplied to the material can be controlled. Even if a is less than 45% by mass (even if the value of c exceeds 55% by mass), it can be used as a bulk RH diffusion source by extending the time of the RH supply diffusion treatment.

More specifically, when the bulk RH diffusion source is a DyFe alloy, if the Dy content is higher than 59.26 mass% (the mass content ratio of Dy in the DyFe ₂ compound phase (molar ratio)), the bulk RH diffusion source is A DyFe ₂ compound phase (molar ratio) and a Dy phase or a DyFe ₂ compound phase (molar ratio) and a phase rich in Dy are formed. Since the DyFe alloy has a eutectic point at 890 ° C., a liquid phase is generated when the bulk RH diffusion source is heated to a temperature higher than 890 ° C. It is considered that the generation of this liquid phase is related to the welding of the bulk RH diffusion source and the RTB-based sintered magnet. For example, when a bulk RH diffusion source having a composition of Dy ₈₈ Fe ₁₂ (mass%) is subjected to RH supply diffusion treatment at 900 ° C., the bulk RH diffusion source melts and is welded to the R-T-B system sintered magnet. As the Dy content is lower than the eutectic composition, the amount of liquid phase produced decreases, making it difficult to weld.

Therefore, if the value of a is 75% by mass or less (the value of c is 25% by mass or more), there are many high melting point DyFe ₂ compound phases (molar ratio) in the bulk RH diffusion source, and therefore RH supply. Even if some liquid phase is present during the diffusion treatment, substantially no welding occurs with the RTB-based sintered magnet.

  Thus, by setting the value of a to 45 mass% or more and 75 mass% or less (the value of c being 25 mass% or more and 55 mass% or less), the bulk RH diffusion source, the RTB-based sintered magnet, Can be prevented. Therefore, the bulk RH diffusion source and the R-T-B system sintered magnet material can be disposed adjacent to each other without a gap, and the processing amount per unit volume during the RH supply diffusion process can be increased. . Further, since the bulk RH diffusion source is prevented from being welded to the R-T-B system sintered magnet material, it can be reused, and the manufacturing cost can be reduced in the mass production scale.

As described above, a part of RH can be substituted with RL (Nd and / or Pr). For example, when the value of a is 70% by mass and the value of b is 10% by mass, RH _70-10 RL ₁₀ Fe ₃₀ (% by mass) is obtained (when d is 0% by mass). That is, RH ₆₀ RL ₁₀ Fe ₃₀ (mass%).

It is inevitable that the content of RH decreases by repeatedly performing the RH supply diffusion treatment. As described above, when the bulk RH diffusion source is a DyFe alloy, if the Dy content is higher than 59.26% by mass, the bulk RH diffusion source is converted into a DyFe ₂ compound (molar ratio) and a Dy phase or a DyFe ₂ compound phase ( Molar ratio) and a phase rich in Dy, but when the Dy content is 59.26% by mass or less, the phase that becomes a liquid phase during the RH supply diffusion treatment, such as the Dy phase or the phase rich in Dy, is reduced. In the RH supply diffusion treatment, only a solid phase is present. When the RH supply diffusion treatment is performed in this state, the Dy content near the surface of the bulk RH diffusion source gradually decreases, resulting in a heterogeneous structure. When this bulk RH diffusion source is reused repeatedly, the number of repetitions is increased. As the amount increases, the supply amount of Dy decreases. That is, if the bulk RH diffusion source is repeatedly reused under the same RH supply diffusion treatment conditions, the effect of improving the _{HcJ of the RTB} -based sintered magnet after the RH supply diffusion treatment decreases as the number of repetitions increases. .

By replacing a part of RH with RL, even if the bulk RH diffusion source is repeatedly reused under the same RH supply diffusion treatment conditions, the R-T-B system firing after the RH supply diffusion treatment is performed regardless of the number of repetitions. A stable _HcJ improvement effect can be obtained in the magnet. This is considered to be due to the following reasons. In the following description, the case where RL is Nd will be described. However, the case where RL is Pr and Nd and Pr are basically the same reason.

Nd and Fe hardly form a compound. For example, a compound phase such as NdFe ₂ (molar ratio) or NdFe ₃ (molar ratio) is not formed. Further, a liquid phase is generated at a temperature lower than that of the alloy of Dy and Fe. Therefore, a liquid phase is easily obtained during the RH supply diffusion treatment, and the presence of an appropriate amount of this liquid phase may gradually reduce the Dy content near the surface of the bulk RH diffusion source during the RH supply diffusion treatment. It is suppressed and the internal structure of the bulk RH diffusion source is homogenized. Thereby, even if the bulk RH diffusion source is repeatedly reused under the same RH supply diffusion treatment conditions, a certain amount of RH can be supplied to the R-T-B system sintered magnet material regardless of the number of repetitions. A stable _HcJ improvement effect can be obtained. This also allows the RH in the bulk RH diffusion source to be used without waste.

  Also, for example, when preparing a bulk RH diffusion source made of a sintered alloy, if the content of RH decreases (when the content of Fe increases), the amount of liquid phase generated during sintering decreases and sintering occurs. Although it becomes difficult, by substituting RH for RH, there is an advantage that the amount of liquid phase generated increases and sintering becomes easier.

  If the value of b (content of RL) exceeds 20% by mass, the possibility that the bulk RH diffusion source and the RTB-based sintered magnet are welded increases, which is not preferable. Therefore, the value of b is preferably 20% by mass or less, and more preferably 5% by mass or more and 20% by mass or less. RL is Nd and / or Pr. In particular, Nd is used as a raw material in the process of preparing an R-T-B type sintered magnet material, so that the raw material procurement cost is reduced by diverting the raw material. can do.

  In the composition formula, the Fe content is represented by cd, and the value of c is 25% by mass or more and 55% by mass or less. The value of d is the content of M and is 0% by mass or more and 15% by mass or less. That is, part of Fe can be replaced with M (Co and / or Al). The reason for limiting c when the value of d is 0% by mass (without M substitution) is as described above for the reason for limiting a.

By replacing a part of Fe with M, the amount of liquid phase in the bulk RH diffusion source during the RH supply diffusion treatment increases, so that the Dy content near the surface of the bulk RH diffusion source gradually decreases. Is suppressed, and the internal structure of the bulk RH diffusion source is homogenized. Thereby, even if the bulk RH diffusion source is repeatedly reused under the same RH supply diffusion treatment conditions, a certain amount of RH can be supplied to the R-T-B system sintered magnet material regardless of the number of repetitions. A stable _HcJ improvement effect can be obtained. Further, the RH in the bulk RH diffusion source can be used without waste. Furthermore, since Co and Al are used as raw materials in the step of preparing the R-T-B system sintered magnet material, the raw material procurement costs can be reduced by diverting the raw materials.

  As M, together with Co and / or Al, B, C, Mg, Si, P, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, At least one selected from Sb, Te, Hf, Ta, W, Au, and Bi may be contained.

When the value of d (content of M) exceeds 15% by mass, when M is Co, there is a high possibility that the bulk RH diffusion source and the RTB-based sintered magnet are welded, and M is Al. In such a case, the supply amount of RH decreases, which is not preferable. Therefore, the value of d is preferably 15% by mass or less, and more preferably 5% by mass or more and 15% by mass or less. For example, when the value of a is 70% by mass, the value of b is 10% by mass, the value of c is 30% by mass, and the value of d is 15% by mass, RH _70-10 RL ₁₀ Fe _30-15 M ₁₅ (Mass%). That is, RH ₆₀ RL ₁₀ Fe ₁₅ M ₁₅ (mass%).

As described above, when the bulk RH diffusion source is a DyFe alloy, if the Dy content is higher than 59.26% by mass, the bulk RH diffusion source is converted into a DyFe ₂ compound (molar ratio) and a Dy phase or a DyFe ₂ compound phase ( Molar ratio) and a phase rich in Dy, but when RH (Dy) is partially substituted with RL (for example, Nd) and Fe is partially substituted with Co, the configuration of the bulk RH diffusion source The phases are mainly a (DyNd) ₃ Co compound phase (molar ratio) and a (DyNd) (FeCo) ₂ compound phase (molar ratio). When a part of RH (Dy) is substituted with RL (for example, Nd) and a part of Fe is substituted with Al, the constituent phase of the bulk RH diffusion source is mainly (DyNd) ₃ Al compound phase ( Molar ratio) and / or (DyNd) ₂ Al compound phase (molar ratio) and (DyNd) FeAl compound phase (molar ratio).

  Impurities that are inevitably mixed in the manufacturing process can be allowed in the bulk RH diffusion source.

  In the bulk RH diffusion source of the present invention, the term “bulk” means “a bulky substance such as a lump of crystals / solids that has a three-dimensional spread and is in a bulky state. , "Refers to those whose effects are negligible." (Iwanami Rikagaku Dictionary 5th Edition). Specifically, it is a green compact, a cast alloy, a roll quenched alloy, a sintered alloy, and the like. Each will be described in detail below.

  The green compact is obtained by compressing and hardening a powder. For example, an alloy of RH and Fe having the above-described composition can be prepared by pulverizing to a required particle size and then molding. Although it has the advantage that it can be prepared relatively easily, it must be handled with care because of its low strength, and the powder on the surface of the green compact must be welded to the RTB-based sintered magnet. There are also disadvantages.

  The cast alloy is an alloy obtained by casting a molten metal on a mold, and is a so-called ingot. Although there is an advantage of using an ingot cast into a mold of a required shape as it is as a bulk RH diffusion source without processing it as it is, cracking, cracking or warping occurs when the thickness is reduced, so that only a relatively thick one can be prepared There are disadvantages. In order to reduce the thickness, grinding or the like may be performed. However, the cost required for the processing increases, and RH contained in the processing waste is wasted, so that the amount of RH used cannot be reduced.

  The roll quenching alloy is a thin plate-like alloy that is brought into contact with a rotating roll and quenched. Although it is a cast alloy in terms of casting an alloy, the present invention distinguishes between a cast alloy and a roll quenching alloy from the viewpoint of solidifying by contact with a roll without using a mold. According to the roll quenched alloy, a plate-like alloy having a relatively small thickness can be obtained directly. However, a specific shape (for example, a rectangle or a circle) cannot be formed only by casting like an ingot. Therefore, grinding and the like are necessary for dimension adjustments other than the thickness, leading to an increase in cost, and RH contained in the processing waste is wasted, so that the amount of RH used cannot be reduced. In addition, since the roll quenched alloy is relatively thin, it is likely to crack or crack. Accordingly, it is difficult to prepare a large plate-like bulk RH diffusion source.

  A sintered alloy is a powder that is molded and sintered. After the RH and Fe alloy having the above composition is pulverized to a required particle size, it is molded and sintered, or it is required to have the above composition. It can be prepared by mixing RH powder and Fe powder having a particle size, and molding and sintering the mixed powder. Moreover, it can prepare also by using the said cast alloy and roll quenching alloy as a raw material of a sintered alloy, and grind | pulverizing, shape | molding, and sintering them. In this case, a cast alloy or roll quenched alloy that cannot be used as a bulk RH diffusion source as it is can be used as a sintered alloy, and the manufacturing cost can be reduced. Furthermore, the self-generated in the process of preparing the raw material alloy and / or the RTB-based sintered magnet material used in the process of preparing the RTB-based sintered magnet material for the cast alloy or the roll quenching alloy By mixing the generated waste, the manufacturing cost can be further reduced. In particular, by using the self-generated waste generated in the process of preparing the R-T-B system sintered magnet material, it is possible to recycle the self-generated waste, and it is possible to recycle RH, which is a rare metal. The amount of use can be reduced. The mixing may be performed after mixing each alloy and self-generated waste before pulverization, or may mix each alloy and self-generated waste after pulverization.

  Since the sintered alloy can be used as it is without being processed, there is no need for grinding or the like, and no processing waste is generated. Therefore, the processing cost can be reduced and the amount of RH used can be reduced without wasting RH contained in the processing waste. In addition, the equipment used for pulverization, molding and sintering can be the same as the existing equipment used for the production of the RTB-based sintered magnet material, so there is no need to prepare new equipment. It can be prepared relatively easily without an increase in cost. In addition, as for the mold during molding, the manufacturing cost can be reduced by using the mold used in the step of preparing the R-T-B system sintered magnet material for performing the RH supply diffusion process. There are advantages. Further, the thickness can be easily adjusted, and a relatively thin one can be easily prepared. In addition, there is an advantage that it is easy to prepare a plurality of bulk RH diffusion sources having the same shape and the same thickness and excellent in dimensional accuracy.

  As the bulk RH diffusion source of the present invention, those in any of the above states can be used, but consideration is given to prevention of welding with the R-T-B system sintered magnet and repeated reuse of the bulk RH diffusion source. In this case, any one of a sintered alloy, a cast alloy, and a roll quenched alloy is preferable, and a sintered alloy is particularly preferable in consideration of a reduction in the amount of RH used and a reduction in manufacturing cost.

  The size (width and length) of the bulk RH diffusion source is not particularly limited, but the width and length are the same as or greater than those of the RTB-based sintered magnet material disposed adjacent to the RH supply diffusion treatment. Is preferred.

  The thickness of the bulk RH diffusion source is not particularly limited, but it is desirable that the thickness is as thin as possible in order to further increase the processing amount per unit volume during the RH supply diffusion processing. However, in the case of repeated reuse, the greater the thickness, the greater the number of times it can be reused. Considering these, the thickness of the bulk RH diffusion source is preferably 0.3 mm or more and 5 mm or less.

Below, the manufacturing method which improves _HcJ of a _RTB system sintered magnet by supplying and diffusing heavy rare earth elements RH using the bulk RH diffusion source of this invention is _demonstrated .
The manufacturing method is roughly
A step of preparing an RTB-based sintered magnet material;
Preparing a bulk RH diffusion source;
A process of arranging an R-T-B sintered magnet material and a bulk RH diffusion source adjacent to each other;
RH supply diffusion process,
Consists of.
Since the process for preparing the bulk RH diffusion source is as described above, the other processes will be described below.

[Step of preparing an RTB-based sintered magnet material]
In the present invention, an R-T-B based sintered magnet material (R is at least one of rare earth elements and always contains Nd, and T is at least one of transition metal elements and always contains Fe) is known. R-T-B system sintered magnet material manufactured by the above composition and manufacturing method can be used.

[Step of arranging the RTB-based sintered magnet material and the bulk RH diffusion source adjacent to each other]
The RTB-based sintered magnet material and the bulk RH diffusion source are respectively prepared, and the RTB-based sintered magnet material and the bulk RH diffusion source are arranged adjacent to each other. The “adjacent arrangement” is not limited as long as it is arranged adjacent to each other. Of course, the bulk RH diffusion source of the present invention is difficult to weld with the RTB-based sintered magnet by being in the bulk and by making the contents of RH and Fe within a specific range, so that they contact each other. It does not matter.

  For example, when emphasizing an increase in the processing amount per unit volume during the RH supply diffusion treatment, the bulk RH diffusion source and the R-T-B system sintered magnet material are placed adjacent to each other without being spaced from each other. It is preferable. In addition, when emphasizing workability improvement in the adjacent placement process using a processing case as described later, it is easy to load and recover a bulk RH diffusion source and an R-T-B system sintered magnet material. In order to achieve this, it is preferable to arrange them adjacent to each other so as not to contact each other.

  In any case, the bulk RH diffusion source of the present invention is difficult to weld with the RTB-based sintered magnet and does not need to be spaced apart to prevent welding. It is unnecessary. Therefore, compared with the said patent document 1, the processing amount per unit volume at the time of RH supply spreading | diffusion processing can be increased significantly, and reduction of manufacturing cost can be aimed at in implementation of mass production scale.

  FIG. 1 is an explanatory view showing an example in which an RTB-based sintered magnet material and a bulk RH diffusion source are arranged adjacent to each other. In FIG. 1, a bulk RH diffusion source 2 having a size slightly larger than that of the RTB-based sintered magnet material 1 is used. As shown in FIG. 1, an R-T-B system sintered magnet material 1 and a bulk RH diffusion source 2 are arranged adjacent to each other. At this time, it is preferable that both ends after the adjacent arrangement are the bulk RH diffusion sources 2. That is, it is preferable that the bulk RH diffusion source 2 and the R—T—B system sintered magnet material 1 are alternately disposed adjacent to each other in the order, and finally the bulk RH diffusion source 2 ends. Thereby, RH can be supplied from both surfaces of all RTB-based sintered magnet materials 1. In addition, although the example arrange | positioned adjacent in the left-right direction (horizontal direction) in the figure was shown in FIG. 1, you may arrange | position adjacent in the up-down direction (vertical method) in the figure with the same structure.

  As shown in FIG. 1, since the bulk RH diffusion source 2 according to the present invention is prevented from welding with the R-T-B system sintered magnet, the bulk RH diffusion source 2 and the R-T-B system sintered magnet are used. The material 1 can be placed adjacent to each other without contact with the material 1. Therefore, the processing amount per unit volume at the time of RH supply diffusion processing can be increased.

  FIG. 2 is an explanatory view showing an example of a processing case for arranging an RTB-based sintered magnet material and a bulk RH diffusion source adjacent to each other. The processing case 3 has an opening (on the front side in FIG. 2) on one side, and uneven portions are provided at the same interval on the inner side of the top plate and the inner side of the bottom plate. In the drawing, a bulk RH diffusion source is inserted into a space where upper and lower portions are formed with concave portions, and an RTB-based sintered magnet material is inserted into a space where upper and lower portions are formed with convex portions. That is, the width of the recess (the horizontal dimension in the figure), the length of the recess (the dimension in the depth direction in the figure), and the height of the recess (the vertical dimension in the figure) are the dimensions of the bulk RH diffusion source (thickness, The width of the convex part, the length of the convex part, and the height of the convex part are substantially the same as the dimensions of the RTB-based sintered magnet material. Designed to the same dimensions.

  FIG. 3 shows an example in which the bulk RH diffusion source 2 is disposed adjacent to the space where the upper and lower portions of the processing case 3 are formed with concave portions, and the RTB-based sintered magnet material 1 is disposed adjacent to the space where the upper and lower portions are formed with convex portions. It is explanatory drawing which shows. The R-T-B sintered magnet material 1 and the bulk RH diffusion source 2 are slightly spaced so as not to contact each other in order to facilitate the insertion into the processing case 3. By using the processing case 3, the RTB-based sintered magnet material 1 and the bulk RH diffusion source 2 can be easily arranged adjacent to each other, the workability of the arrangement process is greatly improved, and the production efficiency is improved. Can be made. Moreover, since the RTB-based sintered magnet material 1 and the bulk RH diffusion source 2 can be easily carried after the adjacent placement, the work of placing the processing case 3 in a furnace such as a heat treatment furnace is very easy. Become.

  The processing case 3 should just select the material similar to the well-known sintering case and heat processing case used with the manufacturing method of RTB system sintered magnet raw material, such as Mo. Moreover, the opening part of the processing case 3 may remain open or may be closed by a lid member.

  In FIG. 2 and FIG. 3, the bulk RH diffusion source 2 having a slightly larger size than the R-T-B type sintered magnet material 1 is used, but both may have the same size. Further, in FIGS. 2 and 3, the processing case 3 in which the uneven portions are provided at the same interval on the inner side of the top plate and the inner side of the bottom plate is used. -A T-B type sintered magnet material and a bulk RH diffusion source may be charged.

[Process for RH supply diffusion treatment]
The RTB-based sintered magnet material and the bulk RH diffusion source adjacently arranged as described above are heated to a temperature of 800 ° C. or higher and 1000 ° C. or lower in a reduced-pressure atmosphere having a pressure of 50 Pa or lower. By this heating, RH in the bulk RH diffusion source is vaporized, and the RH is diffused into the RTB-based sintered magnet material while being supplied to the surface of the RTB-based sintered magnet material. . In the present invention, this is called RH supply diffusion processing.

  In the RH supply diffusion treatment, the atmosphere during the treatment is a reduced pressure atmosphere, and the pressure is preferably 50 Pa or less. If the pressure exceeds 50 Pa, the amount of RH supplied to the RTB-based sintered magnet material is reduced, and it takes time for the RH supply diffusion treatment, which is not preferable. The lower limit of the pressure is not particularly limited, but is preferably 0.001 Pa or more in order to suppress as much as possible RL and M that are vaporized from the bulk RH diffusion source. Also, when the RH content is high and the temperature is high, if the pressure is low, the supply of RH becomes excessive, and the bulk RH diffusion source and the R-T-B system sintered magnet may be easily welded. In that case, the temperature during processing may be set lower and the supply of RH may be reduced.

  In the RH supply diffusion treatment, the temperature during the treatment is preferably 800 ° C. or higher and 1000 ° C. or lower. If it is less than 800 degreeC, since the amount of RH supplied to a R-T-B type | system | group sintered magnet raw material will decrease and time will be required for a RH supply diffusion process, it is unpreferable. On the other hand, if the temperature exceeds 1000 ° C., it is not preferable because intragranular diffusion is likely to occur. A more preferable temperature is 900 ° C. or higher and 950 ° C. or lower. By combining with the pressure condition, the RH supply diffusion treatment can be performed in a short time without causing intragranular diffusion.

  In the RH supply diffusion process, the processing time is not particularly limited. This is because it varies depending on the charged amount, shape, processing pressure, processing temperature, etc. of the RTB-based sintered magnet material and the bulk RH diffusion source. However, if the treatment time is too long, the production cost is increased. Therefore, it is desirable to set the above conditions so that the treatment can be carried out preferably in about 10 minutes to 24 hours, more preferably in about 1 hour to 6 hours.

  As the heat treatment furnace for performing the RH supply diffusion treatment, an existing heat treatment furnace used for manufacturing an RTB-based sintered magnet material can be used. Therefore, it is not necessary to use large-scale equipment or new equipment.

[RH diffusion processing]
By the RH supply diffusion treatment, the RH in the bulk RH diffusion source is vaporized, and the vaporized RH is supplied to the surface of the R-T-B system sintered magnet material. can be diffused therein, it is possible to improve the H _cJ while suppressing a decrease in B _r of R-T-B based sintered magnet, the R-T-B based sintered by the RH supply diffusion process For the purpose of further diffusing RH supplied to the inside of the magnet, RH diffusion processing described below may be performed.

The RH diffusion process refers to heating without performing supply of RH from a bulk RH diffusion source after performing the RH supply diffusion process. For example, when the RH diffusion process is performed after the RH supply diffusion process, the pressure is such that RH is not supplied from the bulk RH supply source (for example, a pressure exceeding 50 Pa), preferably 700 ° C. or more and 1000 ° C. or less, more preferably Is performed at 800 ° C. or higher and 950 ° C. or lower. Alternatively, after performing the RH supply diffusion treatment, when only the RTB-based sintered magnet is recovered, the vacuum or inert gas below atmospheric pressure is applied to the RTB-based sintered magnet. In the atmosphere, the RH diffusion treatment is preferably performed at 700 ° C. or higher and 1000 ° C. or lower, more preferably 800 ° C. or higher and 950 ° C. or lower. The treatment time of the RH diffusion treatment is, for example, about 10 minutes to 24 hours, more preferably about 1 hour to 6 hours. By the RH diffusion treatment, RH diffusion occurs in the _RTB -based sintered magnet, and RH supplied in the vicinity of the surface layer is further diffused deeper, and _HcJ can be increased as a whole magnet.

[Heat treatment]
After the RH supply diffusion treatment or after the RH diffusion treatment, a heat treatment performed for the purpose of improving the magnet characteristics of the RTB-based sintered magnet may be performed. This heat treatment is the same as the heat treatment performed after sintering in a known method for producing a R-T-B sintered magnet material. Known conditions may be employed for the heat treatment atmosphere, the heat treatment temperature, and the like.

[Repeated reuse of bulk RH diffusion source]
Since the bulk RH diffusion source of the present invention is prevented from being welded to the RTB-based sintered magnet, it can be reused. Hereinafter, an example of a method for repeatedly reusing a bulk RH diffusion source will be described.

  First, the step of preparing the RTB-based sintered magnet material, the step of preparing a bulk RH diffusion source, the step of arranging the RTB-based sintered magnet material and the bulk RH diffusion source adjacent to each other, RH supply A step of diffusion treatment is performed. Thereafter, the used bulk RH diffusion source after the RH supply diffusion treatment is recovered. Then, a new R-T-B system sintered magnet material is prepared, the new R-T-B system sintered magnet material and the used bulk RH diffusion source are arranged adjacent to each other, and then the RH supply diffusion process is performed. The process to perform is implemented.

  Further, when the processing case is used in the process of arranging the R-T-B system sintered magnet material and the bulk RH diffusion source adjacent to each other, after performing the RH supply diffusion processing process, the RH supply diffusion process is performed from within the processing case. Only the later RTB-based sintered magnet is collected, and only the used bulk RH diffusion source is left in the processing case. FIG. 4 shows the process case 3 shown in FIG. 2, in which the RTB-based sintered magnet material 1 and the bulk RH diffusion source 2 are arranged adjacent to each other as shown in FIG. FIG. 5 is an explanatory view showing an example of a state in which only the RTB-based sintered magnet after the RH supply diffusion process is recovered from the processing case 3. As shown in FIG. 4, only the used bulk RH diffusion source 4 is left in the processing case 3 in the position where it was arranged before the RH supply diffusion processing. Next, a new R-T-B system sintered magnet material is prepared, and the R-T-B system sintered magnet after the previously recovered RH supply diffusion treatment is placed at a position in the processing case where it was originally arranged. A new RTB-based sintered magnet material is charged, and a new RTB-based sintered magnet material and a heated bulk RH diffusion source after heating are arranged adjacent to each other in the processing case. And the process of carrying out the said RH supply diffusion process is implemented.

  According to the above method, the bulk RH diffusion source can be repeatedly reused, and the manufacturing cost can be further reduced. Further, by using the processing case, it is possible to improve workability in the process of repeatedly reusing the bulk RH diffusion source, and to improve the production efficiency.

  Furthermore, by using the bulk RH diffusion source of the present invention, the large R-T-B system sintered magnet, which has conventionally been difficult to perform the RH supply diffusion process due to the generation of cracks and cracks, can generate cracks and chips. Can be manufactured on a mass production scale. That is, although the method of Patent Document 3 requires a large-scale apparatus, it is suitable for implementation on a mass production scale, and the RH diffusion source can be reused. However, in the method of Patent Document 3, since the R-T-B system sintered magnet material and the RH diffusion source are moved by rotating the processing chamber, the sintering is caused by collision between the sintered magnet materials or the processing chamber wall. There is a risk of cracking or chipping in the magnet material. In particular, when a large R-T-B sintered magnet material having a large size and weight is processed, the collision energy also increases, so that cracks and chips are more likely to occur.

  On the other hand, when the bulk RH diffusion source of the present invention is used, as described above, the bulk RH diffusion source and the R-T-B system sintered magnet material can be arranged adjacent to each other without any gap therebetween. The amount of processing per unit volume during the RH supply diffusion treatment can be increased, which is suitable for implementation on a mass production scale. Further, since the R-T-B system sintered magnet material and the bulk RH diffusion source are subjected to the RH supply diffusion process in a state of being adjacently disposed, cracks and chips are not generated during the process. Further, by carrying in the state of being adjacently arranged in advance, it is possible to prevent the occurrence of cracks and chips even when charging and unloading the heat treatment furnace. Furthermore, when a processing case is used in the process of RH supply diffusion processing, it becomes possible to prevent cracking and chipping of the R-T-B system sintered magnet material while improving workability.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

Example 1
_RT composed of Nd _30.8 B _0.96 Co _0.89 Al _0.1 Cu _0.09 Ga _0.1 balance Fe (mass%) and having a thickness of 3.5 mm × width 100 mm × length 90 mm -A B-based sintered magnet material was prepared. The magnet characteristics were B _r = 1.43 T and H _cJ = 930 kA / m. The magnet characteristic is a characteristic value after heat treatment performed for the purpose of improving the magnet characteristic.

Bulk RH diffusion sources having a composition of Dy ₇₀ Fe ₃₀ (mass%) and having the states A, D, and symbols A to D shown in Table 1 were prepared. The green compact of symbol A was prepared by crushing a thin plate having a thickness of 0.3 mm obtained by the strip casting method to 425 μm or less and molding it at a pressure of ² ton / cm ² . The cast alloy of symbol B was prepared by cutting and grinding a cast alloy having a thickness of 6.5 mm × width 107 mm × length 95.5 mm. The roll-quenched alloy of symbol C was prepared by selecting and cutting a sheet having a large width and length from an amorphous thin plate having a thickness of 0.5 mm obtained by the strip casting method. The sintered alloy represented by symbol D was cast into a cast alloy having a thickness of 45 mm, a width of 150 mm, and a length of 220 mm by hydrogen pulverization to 149 μm or less, followed by molding at a pressure of ² ton / cm ^2. It was prepared by sintering at 4 ° C. for 4 hours. In the hydrogen pulverization, hydrogen occlusion for introducing hydrogen at a pressure of atmospheric pressure to 500 kPa was performed for 1.5 hours, and after releasing hydrogen, dehydrogenation was performed for 4 hours by heating to 550 ° C. in a reduced pressure atmosphere.

  The bulk RH diffusion sources A to D were placed adjacent to each other on both sides of the RTB-based sintered magnet material without any gap. In addition, the roll quenching alloy of the symbol C was arranged 4 sheets per side so that it might become thickness 0.5mm x width 105mm x length 93mm.

  An R-T-B system sintered magnet material having a bulk RH diffusion source of symbols A to D adjacently disposed on both sides is charged into a heat treatment furnace, and at a temperature of 900 ° C. in a vacuum atmosphere at a pressure of 0.1 Pa. RH supply diffusion treatment was performed for 4 hours. Thereafter, the inside of the furnace was cooled, and only the RTB-based sintered magnet was taken out. The R-T-B system sintered magnet after the RH supply diffusion treatment is subjected to the same heat treatment as the heat treatment performed for the purpose of improving the magnet properties applied to the R-T-B system sintered magnet material, and then each R -Both surfaces of the TB sintered magnet were ground by 0.1 mm. An RTB-based sintered magnet having a thickness of 3.3 mm, a width of 7 mm, and a length of 7 mm was cut out from the RTB-based sintered magnet after double-side grinding, and the magnet characteristics were measured with a BH tracer. The measurement results are shown as single use of the diffusion source in Table 2.

  Next, the used bulk RH diffusion source that has been subjected to the RH supply diffusion treatment once is brought into contact with both surfaces of the new R-T-B system sintered magnet material that has not been subjected to the RH supply diffusion treatment without any interval. After being arranged adjacent to each other, the sample was placed in a heat treatment furnace and subjected to RH supply diffusion treatment at 900 ° C. for 4 hours in a vacuum atmosphere at a pressure of 0.1 Pa. Such RH supply diffusion treatment was repeated five times in total, and the same bulk RH diffusion source was reused five times. After performing the same heat treatment as the heat treatment performed for the purpose of improving the magnet properties applied to the RTB-based sintered magnet material to the RTB-based sintered magnet after the fifth RH supply diffusion treatment, Both sides of each R-T-B system sintered magnet were ground by 0.1 mm. An RTB-based sintered magnet having a thickness of 3.3 mm, a width of 7 mm, and a length of 7 mm was cut out from the RTB-based sintered magnet after double-side grinding, and the magnet characteristics were measured with a BH tracer. The measurement results are shown as the fifth use of the diffusion source in Table 2.

As shown in Table 2, even when using any of the bulk RH diffusion source, compared with the R-T-B based sintered magnet material without RH supply diffusion process, H _cJ is improved while suppressing a decrease in B _r doing. However, sample No. When the green compact of symbol A is used as the bulk RH diffusion source 1, the effect of improving _HcJ is slightly reduced by _reusing it five times.

Thus, as a bulk RH diffusion source, a green compact, cast alloy, using any of the roll quenching alloy and sintered alloy, the effect is obtained that H _cJ can be improved while suppressing a decrease in B _r . However, with green compacts, the effect of improving _HcJ is slightly reduced by repeated reuse five times, so it is considered difficult to reuse many times. is necessary. Further, the casting alloy needs to be processed into a required shape in order to increase the processing amount per unit volume at the time of the RH supply diffusion treatment, which causes an increase in the cost required for the processing and the RH contained in the processing scrap. This is wasted and the amount of RH used cannot be reduced. Roll quenched alloys need to be processed to the required dimensions, and large dimensions cannot be prepared with a single piece, so it takes time for the placement process, and cracks and cracks are likely to occur, so handling is very difficult. Have difficulty.

  Therefore, when considering the repeated reuse of the bulk RH diffusion source, any of sintered alloy, cast alloy and roll quenched alloy is preferable, and when considering reduction of production cost and improvement of production efficiency, it is sintered. Gold is preferred. In particular, since the sintered alloy pulverizes, forms, and sinters the raw material alloy, the size and shape of the raw material alloy are not limited. In addition, since machining such as grinding and cutting is not required, RH contained in the processing waste is not wasted, and the amount of RH used can be reduced, and the manufacturing cost can be greatly reduced. it can.

Example 2
R-T having a composition of Nd _30.8 B _0.96 Co _0.89 Al _0.1 Cu _0.09 Ga _0.1 balance Fe (mass%), thickness 3.5 mm × width 20 mm × length 30 mm -A B-based sintered magnet material was prepared. The magnet characteristics were B _r = 1.43 T and H _cJ = 930 kA / m. The magnet characteristic is a characteristic value after heat treatment performed for the purpose of improving the magnet characteristic.

As a bulk RH diffusion source, two sintered alloys of symbols E to J having the compositions shown in Table 3 were prepared. All the dimensions of the bulk RH diffusion source are 2.5 mm thick × 22 mm wide × 32 mm long. The sintered alloys represented by symbols E to J were subjected to hydrogen pulverization to a 0.3 mm-thick roll quenched alloy and pulverized to 212 μm or less, and then molded at a pressure of ² ton / cm ^2. It was prepared by sintering at 1020 ° C. to 1200 ° C. for 4 hours depending on the composition of the bond gold. Hydrogen pulverization was performed under the same conditions as in Example 1.

  The bulk RH diffusion sources E to J were placed adjacent to each other on both sides of the RTB-based sintered magnet material without any gaps. The RH supply diffusion treatment and the heat treatment were performed under the same conditions as in Example 1 except that the bulk RH diffusion source and the RTB-based sintered magnet material after the adjacent arrangement were set to the treatment temperatures shown in Table 3. The magnet characteristics of the obtained RTB-based sintered magnet were measured under the same conditions as in Example 1. Table 3 shows the measurement results. Moreover, the welding state of the bulk RH diffusion source after the RH supply diffusion treatment and the RTB-based sintered magnet was confirmed. The results are shown in Table 3. In addition, Table 3 shows the amount of Dy used in the RH supply diffusion treatment (reduced weight of bulk RH diffusion source × 100 / RTB-based sintered magnet material weight before RH supply diffusion treatment).

As shown in Table 3, it can be seen that as the Dy content of the bulk RH diffusion source increases, the _{HcJ of the RTB} -based sintered magnet is improved. In addition, according to the present invention, since there is no welding between the bulk RH diffusion source and the RTB-based sintered magnet, it is possible to reuse the bulk RH diffusion source. On the other hand, sample No. using a bulk RH diffusion source of symbol E 5 and 6, although there is no welding between the bulk RH diffusion source and the RTB-based sintered magnet, since the Dy content of the bulk RH diffusion source is small, the conditions of the RH supply diffusion treatment according to this example (900 ° C. And 930 ° C., 4 hours), the amount of RH supplied to the _RTB -based sintered magnet material is small, and the _HcJ is not so improved. Sample No. using a bulk RH diffusion source of symbol J Since No. 12 had a large Dy content in the bulk RH diffusion source, the bulk RH diffusion source and the RTB-based sintered magnet were firmly welded. For this reason, the bulk RH diffusion source and the RTB-based sintered magnet could not be separated, and the magnet characteristics could not be measured. Further, it is impossible to reuse the bulk RH diffusion source.

Comparative Example 1
The same RTB-based sintered magnet material as in Example 2 was prepared, and two casting alloys of symbols K and L having the composition shown in Table 4 and two Dy foils of symbol M were prepared as bulk RH diffusion sources. . The dimensions of the cast alloys of symbols K and L are thickness 2.5 mm × width 22 mm × length 32 mm. The dimension of the Dy foil of symbol M was 0.025 mm thickness × 20 mm width × 30 mm length, and had the same width and length as the RTB-based sintered magnet material. The cast alloys of symbols K and L were prepared by cutting and grinding a cast alloy having a thickness of 6.5 mm × width of 107 mm × length of 95.5 mm, similar to the cast alloy of Example 1. The Dy foil of symbol M purchased a commercial product. In the composition of the bulk RH diffusion source in Table 4, Dy ₁₀₀ (mass%) is Dy metal (pure Dy).

  Bulk RH diffusion sources of symbols K, L, and M were placed adjacent to each other on both surfaces of the RTB-based sintered magnet material without any gaps. The RH supply diffusion treatment and the heat treatment were performed under the same conditions as in Example 1 except that the bulk RH diffusion source and the RTB-based sintered magnet material after the adjacent arrangement were set to the treatment temperatures shown in Table 4. The magnet characteristics of the obtained RTB-based sintered magnet were measured under the same conditions as in Example 1. Table 4 shows the measurement results. Table 4 shows the results of confirmation of the welded state between the bulk RH diffusion source after the RH supply diffusion treatment and the RTB-based sintered magnet. Table 4 shows the amount of Dy used in the RH supply diffusion process.

  As is apparent from Table 4, sample No. When the Dy content is large as in 13 to 15, the bulk RH diffusion source and the RTB-based sintered magnet are welded. Sample No. In Nos. 13 and 14, the bulk RH diffusion source and the RTB-based sintered magnet could not be separated, and the magnet characteristics could not be measured. Sample No. For No. 15, the magnet characteristics were measured after grinding both surfaces of the RTB-based sintered magnet by 0.1 mm in the same manner as in Example 1. Sample No. The amount of Dy used (the reduced weight of the bulk RH diffusion source × 100 / the weight of the RTB-based sintered magnet material before the RH supply diffusion treatment) is “the weight of the foil before the RH supply diffusion treatment = the reduced weight”. It is a value. That is, it was considered that all the foils were supplied to the surface of the RTB-based sintered magnet material.

As in Example 2, as the Dy content increases, the _HcJ of the _RTB -based sintered magnet is improved. Therefore, sample No. 11 (composition of the bulk RH diffusion source _Dy 75 _{Fe 25 (wt%), H cJ = 1340kA /} m) Sample No. than _{H cJ} of _HcJ of 15 (the composition of the bulk RH diffusion source is Dy ₁₀₀ (mass%)) is considered to be higher. However, as shown in Table _{4, H cJ} is slightly decreased, _{B r} is also reduced. This is because when an RTB-based sintered magnet material and a bulk RH diffusion source having a high Dy content are placed in contact with each other, Dy is excessively supplied and intragranular diffusion occurs in the surface layer region. is there. In other words, will the Dy consumed by grain boundary diffusion Dy amount consumed in grains diffusion decreases, H _cJ will not significantly improve, B _r is decreased by intragranular diffusion.

As described above, in order to improve the H _cJ while suppressing a decrease in B _r in the R-T-B based sintered magnet, R _{2 T} 14 _B phase by the grain boundary diffusion (molar ratio) outer shell of the light rare earth elements well be substituted by _Dy, there is no need to replace to the center of the R _{2 T 14} B phase (molar ratio). When substitution is performed up to the center of the R ₂ T ₁₄ B phase (molar ratio), _Br decreases. Therefore, sample no. The occurrence of intragranular diffusion as in the case of 15 RTB-based sintered magnets means that Dy is wasted. This is also apparent from the amount of Dy used in Table 4. 15 is Sample No. with Dy usage amount of 0.50 mass%. Despite _{H cJ} and _{B r} is less than 11, using Dy 1.63 mass%. That is, about two-thirds (1.13 mass%) of Dy is wasted.

As described above, when a bulk RH diffusion source having a high Dy content is placed in contact with the R-T-B system sintered magnet material, the intragranular diffusion occurs in the surface layer region of the R-T-B system sintered magnet material. occurs, with _{B r decreases, H cJ} not significantly improved even. Further, the rare metal Dy is consumed wastefully. According to the present invention, the RH content in the bulk RH diffusion source is 45% by mass or more and 75% by mass or less. In addition to preventing intragranular diffusion in the surface region of the TB sintered magnet material, it is possible to reduce the amount of RH that is a rare metal.

Comparative Example 2
The same RTB-based sintered magnet material as in Example 2 was prepared, and two casting alloys of symbols N and L having the compositions shown in Table 5 were prepared as bulk RH diffusion sources. The casting alloy indicated by symbol L is the same as the casting alloy indicated by symbol L in Comparative Example 1. All dimensions are 2.5 mm thickness × 22 mm width × 32 mm length. The cast alloy of symbol N was prepared by cutting and grinding a cast alloy having a thickness of 6.5 mm × width of 107 mm × length of 95.5 mm, similar to the cast alloy of Example 1.

  As shown in FIG. 7, an RTB-based sintered magnet material and a bulk RH diffusion source are respectively placed on a holding member made of an Nb net in a processing chamber, and an RTB-based system is provided by a spacer. The sintered magnet material and the bulk RH diffusion source were arranged with an interval of 5 mm. Next, RH supply diffusion treatment and heat treatment were performed under the same conditions as in Example 1 except that the treatment temperature shown in Table 5 was set in the treatment chamber. The magnet characteristics of the obtained RTB-based sintered magnet were measured under the same conditions as in Example 1. Table 5 shows the measurement results. Table 5 shows the results of confirmation of the welded state between the bulk RH diffusion source after the RH supply diffusion treatment and the RTB-based sintered magnet. Table 5 shows the amount of Dy used in the RH supply diffusion process.

  This comparative example is a reproduction of the method of Patent Document 1. In Patent Document 1, the R-T-B system sintered magnet material and the bulk RH diffusion source are welded to each other by arranging the R-T-B system sintered magnet material and the bulk RH diffusion source at an interval. Can be prevented. However, as apparent from FIG. 7, the processing amount per unit volume cannot be increased because they are arranged at intervals.

However, in the method of Comparative Example 2, the amount of Dy used is relatively large as shown in Table 5. Sample No. 16 and Sample No. 2 of Example 2. As is clear from comparison with Sample No. ₁₀ , despite the same _HcJ , Sample No. No. 10 Dy usage (0.43% by mass) than sample No. The Dy usage amount of 16 (0.86% by mass) is larger. This is considered to be because RH vaporized from the bulk RH diffusion source is also attached to a holding member or a spacer made of Nb used in the RH supply diffusion treatment. That is, about one half (0.43% by mass) of Dy is wasted due to adhesion to the holding member, spacer, and the like.

  Thus, the RTB-based sintered magnet after the RH supply diffusion treatment is arranged by disposing the RTB-based sintered magnet material and the bulk RH diffusion source having a high Dy content at an interval. Can be prevented from being welded to the bulk RH diffusion source, but Dy is wasted due to adhesion to a holding member, a spacer or the like.

  According to the present invention, since the RH content in the bulk RH diffusion source is 45% by mass or more and 75% by mass or less, it is difficult to weld the RTB-based sintered magnet. The system sintered magnet material and the bulk RH diffusion source can be disposed adjacent to each other without a gap, and the processing amount per unit volume during the RH supply diffusion process can be increased. Further, since a holding member, a spacer and the like are unnecessary, Dy is not consumed wastefully. Therefore, the amount of RH that is a rare metal can be reduced.

Example 3
The same RTB-based sintered magnet material as in Example 2 was prepared, and as a bulk RH diffusion source, the sintered alloy of symbol G used in Example 2 and the symbols O to R of the composition shown in Table 6 were used. And two cast alloys of symbols S to U having the compositions shown in Table 6 were prepared. All the dimensions of the bulk RH diffusion source are 2.5 mm thick × 22 mm wide × 32 mm long. The sintered alloys of symbols O to R were prepared by the same method as symbol G. Moreover, the casting alloys of symbols S to U were prepared by cutting and grinding a casting alloy having a thickness of 6.5 mm × width of 107 mm × length of 95.5 mm.

  Bulk RH diffusion sources of symbol G and symbols O to U were placed adjacent to each other on both sides of the RTB-based sintered magnet material without any gap. The RH supply diffusion treatment is repeated 15 times under the same conditions as in Example 1 except that the bulk RH diffusion source and the RTB-based sintered magnet material after the adjacent arrangement are set to the treatment temperatures shown in Table 6, and the same bulk is used. The RH diffusion source was reused 15 times. The same heat treatment as in Example 1 was performed on the first and fifteenth R-T-B system sintered magnets for reuse of the bulk RH diffusion source, and then the magnet characteristics were measured under the same conditions as in Example 1. Table 6 shows the measurement results. Table 6 shows the results of confirmation of the welded state between the bulk RH diffusion source after the RH supply diffusion treatment and the RTB-based sintered magnet.

As shown in Table 6, Sample No. When a bulk RH diffusion source of symbol G made of 19 DyFe alloys is used, the effect of improving _HcJ is slightly reduced when the bulk RH diffusion source is reused 15 times. In contrast, sample no. When a bulk RH diffusion source in which a part of Dy is substituted with Nd as in 20 to 22 is used, even if the bulk RH diffusion source is reused 15 times, _HcJ hardly changes. That is, by replacing a part of RH with RL, a stable _HcJ improvement effect can be obtained in the _RTB sintered magnet after the RH supply diffusion treatment regardless of the number of repetitions.

  However, sample No. 23, if the content of RL exceeds 20% by mass, the bulk RH diffusion source and the RTB-based sintered magnet are welded, and the bulk RH diffusion source and the RTB-based sintered magnet Could not be separated and the magnet properties could not be measured. For this reason, the bulk RH diffusion source could not be reused repeatedly. This is presumably because the amount of liquid phase generated in the bulk RH diffusion source during the RH supply diffusion process was excessive.

Sample No. When Fe is not contained in the bulk RH diffusion source as in 24 to 26, the bulk RH diffusion source and the RTB-based sintered magnet are welded, and the bulk RH diffusion source and the RTB-based sintering are The magnet could not be separated and the magnet properties could not be measured. For this reason, the bulk RH diffusion source could not be reused repeatedly. This is because a high melting point intermetallic compound such as DyFe ₂ compound (molar ratio) does not exist in the bulk RH diffusion source. Therefore, in such a bulk RH diffusion source, the R-T-B system sintered magnet material and the bulk RH diffusion source must be arranged at an interval as in Patent Document 1 shown in Comparative Example 2. In other words, the amount of processing per unit volume cannot be increased.

Sample No. 19 and sample no. As a result of component analysis of the R-T-B system sintered magnet after repeating the RH supply diffusion treatment for No. 21 15 times in total (no grinding for each side of 0.1 mm), the content of Nd was 30 in all cases. It was 5% by mass. That is, at the time of RH supply diffusion treatment, only RH (Dy) in the bulk RH diffusion source is vaporized and supplied to the RTB-based sintered magnet material, and RL (Nd) is contained in the bulk RH diffusion source. Will remain. Due to the presence of this Nd, the Dy content in the vicinity of the surface of the bulk RH diffusion source is suppressed from gradually decreasing during the RH supply diffusion treatment, and the internal structure of the bulk RH diffusion source is homogenized. Thereby, even if the bulk RH diffusion source is repeatedly reused under the same RH supply diffusion treatment conditions, a certain amount of RH can be supplied to the R-T-B system sintered magnet material regardless of the number of repetitions. A stable _HcJ improvement effect can be obtained, and the RH in the bulk RH diffusion source can be used without waste.

Example 4
The same RTB-based sintered magnet material as in Example 2 was prepared, and as a bulk RH diffusion source, the sintered alloy of symbol P used in Example 3 and the symbols V to Z of the compositions shown in Table 7 were used. Two sintered alloys of A and B, and two cast alloys of D from the symbol B of the composition shown in Table 7 were prepared. All the dimensions of the bulk RH diffusion source are 2.5 mm thick × 22 mm wide × 32 mm long. The sintered alloys of symbols V to Z and A were prepared by the same method as symbol P. Moreover, the casting alloy of the symbol B to D was prepared by cutting and grinding a casting alloy having a thickness of 6.5 mm × width of 107 mm × length of 95.5 mm.

  Symbols P and V to Z and a bulk RH diffusion source of A to D were placed adjacent to each other on both sides of the RTB-based sintered magnet material without any gap. The RH supply diffusion treatment was repeated 25 times under the same conditions as in Example 1 except that the bulk RH diffusion source and the R-T-B sintered magnet material after the adjacent arrangement were set to the treatment temperatures shown in Table 7, and the same bulk was used. The RH diffusion source was reused 25 times repeatedly. The same heat treatment as in Example 1 was performed on the first and 25th R-T-B system sintered magnets for reuse of the bulk RH diffusion source, and then the magnet characteristics were measured under the same conditions as in Example 1. Table 7 shows the measurement results. Table 7 shows the results of confirmation of the welded state between the bulk RH diffusion source after the RH supply diffusion treatment and the RTB-based sintered magnet.

As shown in Table 7, sample no. In the case of using a bulk RH diffusion source of symbol P made of a sintered alloy in which a part of 27 Dy is substituted with Nd, when the bulk RH diffusion source is reused 25 times, the effect of improving _HcJ is slightly reduced. Yes. On the other hand, Sample No. When a bulk RH diffusion source in which a part of Dy is substituted with Nd and a part of Fe is substituted with Co or Al as in 28 to 33 is used, the bulk RH diffusion source may be reused 25 times. , H _cJ hardly changes. That is, by replacing a part of RH with RL and replacing part of Fe with M, stable quality with little change in H _cJ even if the number of times of reusing the bulk RH diffusion source is increased. R-T-B sintered magnets can be manufactured.

  However, sample No. When the total content of RH and RL is too large as in 34 and 35, the bulk RH diffusion source and the RTB-based sintered magnet are welded, and the bulk RH diffusion source and the RTB-based sintering are welded. The magnetized magnet could not be separated, and the magnet characteristics could not be measured. For this reason, the bulk RH diffusion source could not be reused repeatedly. This is presumably because the amount of liquid phase generated in the bulk RH diffusion source during the RH supply diffusion process was excessive.

Sample No. When the content of M exceeded 15% by mass as in 36 and 37, when M was Co, the bulk RH diffusion source and the RTB-based sintered magnet were welded. For this reason, the bulk RH diffusion source and the RTB-based sintered magnet could not be separated, and the magnet characteristics could not be measured. Also, the bulk RH diffusion source could not be reused repeatedly. On the other hand, when M is Al, the amount of RH supplied to the _RTB -based sintered magnet material is reduced, and the _HcJ improvement effect is reduced. Sample No. Regarding No. 37, since the magnet characteristics decreased with the number of repetitions of the bulk RH diffusion source, the 25th magnet characteristics were not measured. Furthermore, sample no. Even when the bulk RH diffusion source does not contain Fe as in 38, the amount of RH supplied to the _RTB -based sintered magnet material is reduced, and the _HcJ improvement effect is reduced. Sample No. No. 38 was not measured for the 25th magnet property because the magnet property decreased with the number of repetitions of the bulk RH diffusion source.

Before the RH supply diffusion treatment of the sintered alloy of symbol V (Dy ₆₀ Nd ₁₀ Fe ₁₅ Co ₁₅ (mass%)) in which part of Dy is replaced with Nd and part of Fe is replaced with Co, Sample No. . The sintered alloy that was reused 25 times after being reused 25 times was further reused 25 times under the same conditions, and was reused 50 times in total, using an X-ray diffractometer (RINT-2400 manufactured by Rigaku). X-ray diffraction measurement was performed. The obtained X-ray diffraction pattern is shown in FIG. The lower X-ray diffraction pattern of FIG. 5 shows the sintered alloy before the RH supply diffusion treatment, and the upper X-ray diffraction pattern shows the sintered alloy after 50 times reuse.

As shown in the lower part of FIG. 5, when a part of Dy is substituted with Nd and a part of Fe is substituted with Co, the constituent phase of the bulk RH diffusion source (sintered alloy) is mainly (DyNd) ₃ Co compound. It can be seen that it is composed of a phase (molar ratio) and a (DyNd) (FeCo) ₂ compound phase (molar ratio). As shown in the upper part of FIG. 5, after 50 times repeated reuse, although the amount of (DyNd) ₃ Co compound phase (molar ratio) is decreased, the constituent phase is not changed. That is, Co defines a content (% by mass) that substitutes a part of Fe, but in a constituent phase in a bulk RH diffusion source, (DyNd) (FeCo) ₂ compound phase (mol) Ratio) and basically (DyNd) ₃ Co compound phase (molar ratio) not containing Fe. In the bulk RH diffusion source, the (DyNd) ₃ Co compound phase (molar ratio), which has a low melting point due to the inclusion of Co during the RH supply diffusion treatment, becomes a liquid phase and has a high melting point (DyNd) (FeCo) _2. The compound phase (molar ratio) is basically considered to be in a solid phase state.

  In addition, after repeating the RH supply diffusion treatment with the sintered alloy of symbol V 25 times (no grinding for each 0.1 mm on both sides), the sample No. As a result of analyzing the Co content in 28 R-T-B system sintered magnets by ICP emission spectroscopic analysis, the Co content was 0.89% by mass, and the R-T-B system before RH supply diffusion treatment It was the same as Co content (0.89 mass%) of a sintered magnet raw material.

From the above results, during the RH supply diffusion treatment, only Dy in the bulk RH diffusion source is vaporized and supplied to the surface of the RTB-based sintered magnet material. Dy in bulk RH diffusion source, _(DyNd) liquid based on 3 Co compound phase (molar ratio) ((liquid phase derived from _DyNd) 3 Co compound phase (molar ratio)) and _(DyNd) (FeCo) ₂ Although it is thought that it is supplied from any of the compound phases (molar ratio), as shown in the upper part of FIG. 5, as a result, Dy of (DyNd) ₃ Co compound phase (molar ratio) is mainly consumed. That is, the liquid phase based on the (DyNd) ₃ Co compound phase (molar ratio) supplies Dy to the surface of the R-T-B system sintered magnet material, and (DyNd) (FeCo) ₂ compound phase (molar ratio). ) To Dy. The presence of the liquid phase based on this (DyNd) ₃ Co compound phase (molar ratio) suppresses a gradual decrease in the Dy content near the surface of the bulk RH diffusion source, and the internal structure of the bulk RH diffusion source. Is homogenized. Thereby, even if the bulk RH diffusion source is repeatedly reused under the same RH supply diffusion treatment conditions, a constant amount of Dy can be supplied to the R-T-B system sintered magnet material regardless of the number of repetitions. It is considered that a stable _HcJ improvement effect can be obtained. Further, the bulk RH diffusion source decreases in weight as the Dy content decreases, but the apparent volume hardly changes. Therefore, it is considered that the amount of Dy supply is less reduced by the volume change.

Sample No. For the sintered alloy of symbol W (Dy ₆₀ Nd ₁₅ Fe ₁₅ Al ₁₀ (mass%)) used in 30, in which a part of Dy is replaced with Nd and a part of Fe is replaced with Al, the test is repeated 25 times. The structure of the sintered alloy after use was observed by a reflected electron image (BSE image) by FE-SEM (field emission scanning electron microscope). The result is shown in FIG. In addition, component analysis was performed on the white phase indicated by symbol a in the figure and the gray phase indicated by symbol b in the figure by EDX (energy dispersive X-ray spectroscopy) using EPMA (EPMA-1610 manufactured by Shimadzu Corporation). It was. As a result, the white phase component indicated by symbol a in the figure is Dy ₄₉ Nd ₄₂ Al ₉ (mass%), and the gray phase component indicated by symbol b in the figure is Dy ₆₂ Nd ₇ Fe ₂₀ Al ₁₁ (mass). %)Met.

  In addition, after repeating the RH supply diffusion treatment with the sintered alloy of symbol W 25 times in total (no grinding on both sides of 0.1 mm), the sample No. As a result of analyzing the Al content in 30 RTB-based sintered magnets by ICP emission spectroscopic analysis, the Al content was 0.1% by mass, and the RTB system before the RH supply diffusion treatment It was the same as Al content (0.1 mass%) of a sintered magnet raw material.

From the above results, when a part of Dy is substituted with Nd and a part of Fe is substituted with Al, the constituent phase of the bulk RH diffusion source (sintered alloy) is mainly the (DyNd) ₃ Al compound phase (mol). Ratio) and / or (DyNd) ₂ Al compound phase (molar ratio, phase indicated by symbol a in FIG. 6) and (DyNd) FeAl compound phase (molar ratio, phase indicated by symbol b in FIG. 6). It is thought that. That is, Al defines that the content (% by mass) defines a part of Fe, but in the constituent phase in the bulk RH diffusion source, (DyNd) FeAl compound phase (molar ratio) and Basically, Fe is not contained (DyNd) ₃ Al compound phase (molar ratio) and / or (DyNd) ₂ Al compound phase (molar ratio). The bulk RH diffusion source is mainly composed of (DyNd) ₃ Al compound phase (molar ratio) and / or (DyNd) ₂ Al compound phase (molar ratio) and (DyNd) FeAl compound phase (molar ratio) at room temperature. (DyNd) ₃ Al compound phase (molar ratio) and / or (DyNd) ₂ Al compound phase (molar ratio), which has a low melting point due to the inclusion of Al during the RH supply diffusion treatment, becomes a liquid phase, It is considered that the (DyNd) FeAl compound phase (molar ratio) having a high melting point is basically in a solid phase.

In addition, during the RH supply diffusion process, only Dy in the bulk RH diffusion source is vaporized and supplied to the surface of the R-T-B system sintered magnet material. Dy in the bulk RH diffusion source is a liquid phase ((DyNd) ₃ Al compound phase (molar ratio) based on (DyNd) ₃ Al compound phase (molar ratio) and / or (DyNd) ₂ Al compound phase (molar ratio) And / or (DyNd) ₂ Al compound phase (molar ratio) derived liquid phase) and (DyNd) FeAl compound phase (molar ratio) are considered to be supplied, It is thought that it is consumed from the (DyNd) ₃ Al compound phase (molar ratio) and / or (DyNd) ₂ Al compound phase (molar ratio). That is, the liquid phase based on the (DyNd) ₃ Al compound phase (molar ratio) and / or the (DyNd) ₂ Al compound phase (molar ratio) supplies Dy to the surface of the RTB-based sintered magnet material. At the same time, it is considered that Dy is replenished to the (DyNd) FeAl compound phase (molar ratio). The presence of a liquid phase based on this (DyNd) ₃ Al compound phase (molar ratio) and / or (DyNd) ₂ Al compound phase (molar ratio) gradually reduces the Dy content near the surface of the bulk RH diffusion source. And the internal structure of the bulk RH diffusion source is homogenized. Thereby, even if the bulk RH diffusion source is repeatedly reused under the same RH supply diffusion treatment conditions, a constant amount of Dy can be supplied to the R-T-B system sintered magnet material regardless of the number of repetitions. It is considered that a stable _HcJ improvement effect can be obtained.

As described above, even if the number of repeated reuse of the bulk RH diffusion source is increased by substituting part of RH with RL and part of Fe with M, a certain amount of RH can be reduced to R- It can be supplied to a TB-based sintered magnet material, a stable _HcJ improvement effect can be obtained, and RH in the bulk RH diffusion source can be used without waste. In particular, when Co and Al are used as M, since Co and Al are used as raw materials in the process of preparing an R-T-B system sintered magnet material, the raw material procurement cost is diverted by diverting the raw materials. Etc. can be reduced.

Example 5
The same RTB-based sintered magnet material as in Example 2 was prepared, and two sintered alloys of symbols E to H having the compositions shown in Table 8 were prepared as bulk RH diffusion sources. All the dimensions of the bulk RH diffusion source are 2.5 mm thick × 22 mm wide × 32 mm long.

As for the sintered alloy of symbols E and F, Dy ₈₀ Fe ₂₀ (mass%) cast alloy and Nd ₈₀ Fe ₂₀ (mass%) cast alloy were mixed and pulverized to 212 μm or less by hydrogen pulverization under the same conditions as in Example 1. Then, the composition was adjusted by further mixing atomized iron powder, Co powder, and Fe—Al powder, and the mixture was prepared by molding at a pressure of ² ton / cm ² and sintering at 1080 ° C. for 4 hours.

As for the sintered alloy of _{Symbol G} , a powder obtained by grinding a Dy ₈₀ Fe ₂₀ (mass%) cast alloy to 212 μm or less by hydrogen grinding under the same conditions as in Example 1, Nd _26.2 Dy _5.02 Fe _66.62 B: 6 .mu.m jet mill pulverized powder for RTB-based sintered magnet material made of B _0.96 Co _0.9 Al _0.1 Cu _0.1 Ga _0.1 (mass%) is 75:25 After mixing at a rate, it was prepared by molding at a pressure of ² ton / cm ² and sintering at 1080 ° C. for 4 hours. The composition of the obtained sintered alloy was Dy _61.3 Nd _6.6 Fe _31.5 B _0.24 Co _0.23 Al _0.03 Cu _0.03 Ga _0.03 (mass%). No. in Table 8 41 in the bulk RH diffusion source composition of 41 is B, Co, Al, Cu, and Ga (total content 0.56% by mass).

The sintered alloy of symbol _H is a powder obtained by pulverizing a Dy ₈₀ Fe ₂₀ (mass%) cast alloy to 212 μm or less by hydrogen pulverization under the same conditions as in Example 1, and Nd _22.2 Dy _9.02 Fe _66.62. Self-generated scrap of RTB-based sintered magnet material made of B _0.96 Co _0.9 Al _0.1 Cu _0.1 Ga _0.1 (mass%) under the same conditions as in Example 1 Were mixed at a ratio of 75:25, and then molded at a pressure of ² ton / cm ² and sintered at 1080 ° C. for 4 hours. The composition of the obtained sintered alloy was Dy _62.3 Nd _5.6 Fe _31.5 B _0.24 Co _0.23 Al _0.03 Cu _0.03 Ga _0.03 (mass%). No. in Table 8 42 in the bulk RH diffusion source composition of 42 is B, Co, Al, Cu and Ga (total content 0.56% by mass).

  A bulk RH diffusion source of symbol H to H was brought into contact with both surfaces of the R-T-B system sintered magnet material without being spaced apart and adjacently arranged. The RH supply diffusion treatment and the heat treatment were performed under the same conditions as in Example 1 except that the processing temperature shown in Table 8 was used for the bulk RH diffusion source and the RTB-based sintered magnet material after the adjacent arrangement. The magnet characteristics of the obtained RTB-based sintered magnet were measured under the same conditions as in Example 1. Table 8 shows the measurement results. Table 8 shows the results of confirmation of the welded state between the bulk RH diffusion source after the RH supply diffusion treatment and the RTB-based sintered magnet.

As shown in Table 8, it can be seen that excellent _HcJ is obtained with any bulk RH diffusion source. That is, using various raw materials such as raw material alloys used in the process of preparing the RTB-based sintered magnet material and self-generated waste generated in the process of preparing the RTB-based sintered magnet material. The produced sintered alloy can be used as a bulk RH diffusion source. Thereby, raw material waste, sintered magnet defective products, and the like that have been conventionally wasted can be reused, the amount of RH used can be reduced, and the manufacturing cost can be further reduced.

Example 6
_RT composed of Nd _30.8 B _0.96 Co _0.89 Al _0.1 Cu _0.09 Ga _0.1 balance Fe (mass%) and having a thickness of 3.5 mm × width 100 mm × length 90 mm -A plurality of B-based sintered magnet materials were prepared. The magnet characteristics were B _r = 1.43 T and H _cJ = 930 kA / m. The magnet characteristic is a characteristic value after heat treatment performed for the purpose of improving the magnet characteristic.

  As a bulk RH diffusion source, 11 sintered alloys having the composition shown in Table 9 were prepared. The dimensions of the bulk RH diffusion source are 2.5 mm thick × 105 mm wide × 93 mm long. The sintered alloy of symbol R was prepared by the same method as the sintered alloy of symbol D of Example 1.

  In the processing case shown in FIG. 2, the RTB-based sintered magnet material and the bulk RH diffusion source are alternately arranged adjacent to each other as shown in FIG. An interval of about 0.5 mm is provided between the RTB-based sintered magnet material and the bulk RH diffusion source in order to facilitate the insertion into the processing case. The processing case after the adjacent arrangement was placed in a heat treatment furnace, and RH supply diffusion treatment was performed at a temperature of 920 ° C. for 4 hours in a vacuum atmosphere at a pressure of 0.1 Pa. Thereafter, the inside of the furnace was cooled, and only the R-T-B system sintered magnet was taken out, and the bulk RH diffusion source was left as it was as shown in FIG. The R-T-B system sintered magnet after the RH supply diffusion treatment is subjected to the same heat treatment as the heat treatment performed for the purpose of improving the magnet properties applied to the R-T-B system sintered magnet material, and then each R -Both surfaces of the TB sintered magnet were ground by 0.1 mm. An RTB-based sintered magnet having a thickness of 3.3 mm, a width of 7 mm, and a length of 7 mm was cut out from the RTB-based sintered magnet after double-side grinding, and the magnet characteristics were measured with a BH tracer. The measurement results are shown as single use of the diffusion source in Table 9.

  Next, a new R-T-B system sintered magnet material that has not been subjected to the RH supply diffusion process is placed between the bulk RH diffusion sources that have been retained in the processing case. After charging, the processing case was charged into a heat treatment furnace, and RH supply diffusion treatment was performed at a temperature of 920 ° C. for 4 hours in a vacuum atmosphere at a pressure of 0.1 Pa. Such RH supply diffusion treatment was repeated 25 times in total, and the same bulk RH diffusion source was reused 25 times. The RTB-based sintered magnet after the 25th RH supply diffusion treatment was subjected to the same heat treatment as the heat treatment performed for the purpose of improving the magnet properties applied to the RTB-based sintered magnet material, Both sides of each R-T-B system sintered magnet were ground by 0.1 mm. An RTB-based sintered magnet having a thickness of 3.3 mm, a width of 7 mm, and a length of 7 mm was cut out from the RTB-based sintered magnet after double-side grinding, and the magnet characteristics were measured with a BH tracer. The measurement results are shown as the 25th use of the diffusion source in Table 9.

As shown in Table 9, compared to the R-T-B based sintered magnet material without RH supply diffusion process, H _cJ is improved while suppressing a decrease in B _r. Further, even if the bulk RH diffusion source reused repeatedly 25 _{times, H cJ} and _{B r} it is not changed. Further, there was no welding between the bulk RH diffusion source and the RTB-based sintered magnet. Furthermore, by using the processing case, the RTB-based sintered magnet material and the bulk RH diffusion source can be easily arranged adjacent to each other, and the workability of the arrangement process is greatly improved. In addition, since the RTB-based sintered magnet material and the bulk RH diffusion source can be easily carried after the adjacent arrangement, the operation of arranging the processing case in a furnace such as a heat treatment furnace has become very easy.

DESCRIPTION OF SYMBOLS 1 RTB system sintered magnet raw material 2 Bulk RH diffusion source 3 Processing case 4 Used bulk RH diffusion source 11 RTB system sintered magnet body 12 RH bulk body 13 Processing chamber 14 Holding member 15 Spacer

Claims (10)

A bulk RH diffusion source for manufacturing an R-T-B based sintered magnet (R is at least one of rare earth elements and always contains Nd, and T is at least one transition metal element and always contains Fe). And
The composition formula in mass% notation is represented by RH _ab RL _b Fe _cd M _d ,
RH is Dy, RL is Nd and / or Pr, M is Co and / or Al,
45% by mass ≦ a ≦ 75% by mass,
0% by mass ≦ b ≦ 20% by mass,
25% by mass ≦ c ≦ 55% by mass,
0% by mass ≦ d ≦ 15% by mass,
And a bulk RH diffusion source consisting of inevitable impurities.   The bulk RH diffusion source according to claim 1, which is any one of a sintered alloy, a cast alloy, and a roll quenched alloy.   The bulk RH diffusion source according to claim 2, which is a sintered alloy.   4. The bulk RH diffusion source according to claim 3, wherein the sintered alloy is a cast alloy and / or a roll quenched alloy that has been pulverized, molded, and sintered.   The bulk RH diffusion source according to claim 1, wherein 5% by mass ≦ b ≦ 20% by mass.   The bulk RH diffusion source according to any one of claims 1 to 5, wherein RL is Nd.   The bulk RH diffusion source according to claim 1, wherein 5% by mass ≦ d ≦ 15% by mass. 8. The bulk RH diffusion source according to claim 7, wherein RL is Nd, M is Co, and comprises a (DyNd) ₃ Co compound phase and a (DyNd) (FeCo) ₂ compound phase (both of the chemical formulas are expressed in molar ratios). . RL is Nd, M is Al, and contains (DyNd) ₃ Al compound phase and / or (DyNd) ₂ Al and (DyNd) FeAl compound phase (all of the above chemical formulas are expressed in molar ratio). The bulk diffusion source described.   The bulk RH diffusion source according to any one of claims 1 to 9, which has a thickness of 0.3 mm to 5 mm.