WO2016155674A1 - 一种含有Ho和W的稀土磁铁 - Google Patents

一种含有Ho和W的稀土磁铁 Download PDF

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WO2016155674A1
WO2016155674A1 PCT/CN2016/078412 CN2016078412W WO2016155674A1 WO 2016155674 A1 WO2016155674 A1 WO 2016155674A1 CN 2016078412 W CN2016078412 W CN 2016078412W WO 2016155674 A1 WO2016155674 A1 WO 2016155674A1
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rare earth
earth magnet
magnet
weight
rich
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PCT/CN2016/078412
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English (en)
French (fr)
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永田浩
张建洪
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厦门钨业股份有限公司
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Priority claimed from CN201510153000.XA external-priority patent/CN106158202B/zh
Application filed by 厦门钨业股份有限公司 filed Critical 厦门钨业股份有限公司
Priority to US15/562,711 priority Critical patent/US10468168B2/en
Priority to EP16771429.4A priority patent/EP3279906A4/en
Publication of WO2016155674A1 publication Critical patent/WO2016155674A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/12—Both compacting and sintering
    • B22F3/16—Both compacting and sintering in successive or repeated steps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • B22F2009/044—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling by jet milling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2201/00—Treatment under specific atmosphere
    • B22F2201/01—Reducing atmosphere
    • B22F2201/013—Hydrogen
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2201/00—Treatment under specific atmosphere
    • B22F2201/10—Inert gases
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2201/00—Treatment under specific atmosphere
    • B22F2201/20—Use of vacuum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2202/00—Treatment under specific physical conditions
    • B22F2202/05—Use of magnetic field
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2301/00—Metallic composition of the powder or its coating
    • B22F2301/35—Iron
    • B22F2301/355—Rare Earth - Fe intermetallic alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C2202/00—Physical properties
    • C22C2202/02—Magnetic

Definitions

  • the present invention relates to the technical field of manufacturing magnets, and more particularly to a rare earth magnet containing Ho and W.
  • Sintered Nd-Fe-B magnets have excellent magnetic properties and are widely used in wind power generation, nuclear magnetic resonance, automotive, computer, aerospace, household appliances, etc., which leads to the main Nd-Fe-B magnets.
  • the Nd consumption of raw materials is too large.
  • the presence of Ho is large, and it is of great significance to select the part of Ho to replace the metal Nd in the magnet.
  • Ho can significantly improve the coercivity and temperature stability of Nd-Fe-B magnets, it is possible to reduce the high-performance rare earth by replacing the metal Nd in the magnet with the low-cost material Ho which is relatively easy to obtain in industrial production.
  • the overall production cost of the magnet since Ho can significantly improve the coercivity and temperature stability of Nd-Fe-B magnets, it is possible to reduce the high-performance rare earth by replacing the metal Nd in the magnet with the low-cost material Ho which is relatively easy to obtain in industrial production. The overall production cost of the magnet.
  • Liu Xiangyu describes the effect of adding Ho on the magnetic properties and temperature stability of sintered Nd ⁇ Fe ⁇ B permanent magnet materials (magnetic materials and devices, August 2011).
  • the addition of an appropriate amount of Ho can inhibit Nd ⁇ Fe ⁇
  • the formation of a-Fe phase in B alloy ingot promotes the growth of Nd 2 Fe 14 B columnar crystals, so that the Nd-rich phase distribution is relatively uniform, and the sintered Nd-Fe-B magnet has a relatively high degree of densification and good display.
  • Micro-tissue; in addition, a certain amount of Ho addition can improve the intrinsic coercivity and improve the temperature stability of the magnet.
  • Zhang Shimao et al. also described similar content in "Addition of Gd, Ho on the Structure and Properties of Sintered Nd-Fe-B Magnets" (Rare Earths, Vol. 34, No. 1, February 2013).
  • the magnet crystal grains can be refined.
  • the Nd-rich phase is evenly distributed to improve the sintering performance of the magnet.
  • the manufacturing method of the Nd-Fe-B sintered magnet is gradually improved.
  • SC method the popularization of the strip film
  • the thin plate alloy can be easily produced.
  • the crystal structure in the thin plate alloy is relatively uniform and fine, and the Nd-rich phase is also uniformly distributed in units of ⁇ m.
  • the combination of the SC method and the hydrogen breaking method can be obtained.
  • a fine powder having an average particle diameter of 10 ⁇ m or less can also remarkably improve the sintering property of the magnet.
  • the object of the present invention is to overcome the deficiencies of the prior art and to provide a rare earth magnet containing Ho and W.
  • the grain growth of the Ho-containing magnet during sintering is suppressed by a trace amount of W, thereby preventing the magnet containing the Ho AGG is generated to obtain a magnet having high coercive force and high heat resistance.
  • a rare earth magnet containing Ho and W the rare earth magnet containing a main phase of R 2 Fe 14 B, and comprising the following raw material components:
  • R 28 wt% to 33 wt%
  • R is a rare earth element including Nd and Ho, wherein the content of Ho is 0.3 wt% to 5 wt%
  • T is an element mainly comprising Fe and 0 to 18% by weight of Co.
  • the rare earth elements mentioned in the present invention include lanthanum elements.
  • the Ho element can make the Nd-rich phase distribution of the rare earth magnet uniform, thereby improving the sintering property of the magnet, but for rare earth magnets having significantly improved sintering properties, grain abnormal growth (AGG) is extremely likely to occur, and therefore, in the present invention Selective use of trace W to suppress abnormal grain growth (AGG). Since W has different ionic radii and electronic structures from rare earth elements, iron and boron of the main constituent elements, there is almost no R 2 Fe 14 B main phase. W, trace W is precipitated by the precipitation of the main phase of R 2 Fe 14 B during the cooling of the melt, and the migration of the grain boundary is pinned, thereby preventing the AGG from occurring in the sintering process. A magnet with high coercive force and high heat resistance is obtained.
  • the soft grain boundary phase can be hardened to exhibit a lubricating action, and the effect of improving the degree of orientation is also achieved.
  • the rare earth magnet there is an electrolytic cell, a barrel-shaped graphite crucible as an anode, a tungsten (W) rod as a cathode on the axis of the crucible, and a rare earth metal collected by a tungsten crucible at the bottom of the graphite crucible.
  • a rare earth element such as Nd
  • a small amount of W is inevitably mixed therein.
  • other high-melting-point metals such as molybdenum (Mo) may be used as the cathode, and the rare earth metal may be obtained by using molybdenum rhenium to collect the rare earth metal.
  • W may be an impurity of a raw material metal (e.g., pure iron, rare earth metal, B, etc.), and the raw material used in the present invention may be selected depending on the content of impurities in the raw material.
  • a raw material metal e.g., pure iron, rare earth metal, B, etc.
  • the raw material containing W is added in the manner of adding the W metal raw material described in the present invention.
  • Table 1 shows the content of W element in the metal Nd of different workshops in different places.
  • T comprises 2.0 wt% or less selected from the group consisting of Sn, Sb, Hf, Bi, V, Zr, Mo, Zn, Ga, Nb, Ni, Ti, Cr, Si, Mn, S or P. At least one element, 0.8 wt% or less of Cu, 0.8 wt% or less of Al, and the balance Fe.
  • the rare earth magnet is obtained by the steps of preparing the rare earth magnet raw material melt into an alloy for a rare earth magnet, and the alloy for the rare earth magnet is a raw material alloy melt a material casting method, which is obtained by cooling at a cooling rate of 10 2 ° C /sec or more and 10 4 ° C / sec or less; a process of coarsely pulverizing the rare earth magnet with an alloy and then finely pulverizing it to form a fine powder;
  • the powder is obtained by a magnetic field molding method to obtain a molded body, and the formed body is sintered in a vacuum or an inert gas to obtain a sintered rare earth magnet having an oxygen content of 1000 ppm or less.
  • the present invention selects to complete the entire manufacturing process of the magnet in a low-oxygen environment, and to control the O content to a low level.
  • a rare earth magnet having a higher oxygen content 1000 ppm or more
  • the rare earth magnet having a low oxygen content (below 1000 ppm) has excellent magnetic properties, it is easy to generate AGG, and the present invention also achieves the effect of reducing AGG in a low oxygen content magnet by adding a very small amount of W.
  • the alloy for a rare earth magnet is obtained by cooling a raw material alloy melt by a strip casting method at a cooling rate of 10 2 ° C /sec or more and 10 4 ° C / sec or less.
  • the powder is obtained by the combination of the strip casting method (SC method) and the hydrogen breaking method to further improve the dispersibility of the Nd-rich phase, and the presence of W can also prevent the Ho-containing powder obtained through the above process from being sintered.
  • AGG occurs during the process, and a magnet having good sinterability, coercive force (Hcj), squareness (SQ), and high heat resistance is obtained.
  • the rare earth magnet is a Nd-Fe-B based sintered magnet.
  • the rare earth magnet has a W-rich region of 40 ppm or more and 3000 ppm or less in a crystal grain boundary, and the W-rich region accounts for at least 50% by volume of the crystal grain boundary.
  • the trace amount W is precipitated by the precipitation of the main phase of the R 2 Fe 14 B during the cooling of the melt, and is concentrated in the grain boundary to fully exert its function.
  • T comprises from 0.1 wt% to 0.8 wt% of Cu
  • Cu distributed in the grain boundary increases the low melting liquid phase
  • an increase in the low melting liquid phase improves the distribution of W
  • W in the present invention, W
  • the distribution in the grain boundary is quite uniform, and the distribution range exceeds the distribution range of the Nd-rich phase, which basically covers the entire Nd-rich phase. It can be considered as evidence that W plays a pinning effect and hinders grain growth, and an appropriate amount of Cu is added. Thereafter, the phenomenon that AGG occurs during the sintering process of the Ho-containing magnet is further reduced.
  • T further comprises 0.1 wt% to 0.8 wt% of Al.
  • Al refines the grain of the alloy while making the volume of the Nd-rich phase and the B-rich phase smaller, and part of the Al enters the rich
  • the Nd phase interacts with Cu to improve the wetting angle between the Nd-rich phase and the main phase, so that the Nd-rich phase and W are uniformly distributed along the boundary, reducing the occurrence of AGG.
  • T further includes at least one selected from the group consisting of Sn, Sb, Hf, Bi, V, Zr, Mo, Zn, Ga, Nb, Ni, Ti, Cr, Si, Mn, S, or P.
  • the element, the total composition of the above elements is from 0.1% by weight to 2.0% by weight of the rare earth magnet component.
  • the rare earth magnet consists of at least two phases including a W-rich grain boundary phase and a Ho-rich main phase.
  • the present invention has the following characteristics:
  • the rich Ho phase will enter the main phase to form Ho 2 Fe 14 B (the intensity of the anisotropy field of R 2 Fe 14 B is as follows: Gd ⁇ Nd ⁇ Pr "Ho ⁇ Dy "Tb), visible, Ho
  • the formation of 2 Fe 14 B can increase the anisotropy field of the magnet.
  • both the coercive force and the anisotropy field of the magnet are significantly improved by the combination of the grain boundary W-rich phase and the main phase rich Ho phase.
  • the soft grain boundary phase can be hardened, which acts as a lubricant and improves the degree of orientation.
  • the Nd-rich phase and W can be distributed uniformly along the boundary to reduce the occurrence of AGG.
  • the presence of Ho is large and is a relatively low-cost material that can be obtained in industrial production.
  • the invention selects to replace the metal Nd in the magnet by Ho, which has the characteristics of high comprehensive economic effect and high industrial value.
  • Fig. 1 is a result of EPMA detection of the sintered magnet of Example 2 of the first embodiment.
  • the sintered magnets obtained in the first to fourth embodiments were all measured by the following detection methods.
  • Magnetic performance evaluation process The sintered magnet was magnetically tested using the NIM ⁇ 10000H BH bulk rare earth permanent magnet non-destructive measurement system of China Metrology Institute.
  • the sintered magnet was polished in the horizontal direction, and the AGG mentioned in the present invention was a crystal grain having a particle diameter exceeding 40 ⁇ m, which was included per 1 cm 2 .
  • Each serial number group was prepared according to the elemental composition in Table 2, and 10 Kg of raw materials were weighed and prepared separately.
  • Smelting process 1 part of the prepared raw material is placed in a crucible made of alumina, and vacuum-smelting is performed in a vacuum induction melting furnace at a temperature of 1600 ° C or lower in a vacuum of 10 -2 Pa.
  • Casting process Ar gas was introduced into a melting furnace after vacuum melting to bring the gas pressure to 55,000 Pa, and then casting was performed by a single roll quenching method, and a quenched alloy was obtained at a cooling rate of 10 2 ° C / sec to 10 4 ° C / sec.
  • Hydrogen breaking and pulverizing process the hydrogen quenching furnace in which the quenching alloy is placed is evacuated at room temperature, and then hydrogen gas having a purity of 99.5% is introduced into the hydrogen breaking furnace to a pressure of 0.09 MPa, and after standing for 2 hours, the temperature is raised while vacuuming. The mixture was evacuated at a temperature of 500 ° C for 1.5 hours, and then cooled, and the powder after the pulverization of hydrogen was taken out.
  • the sample after the hydrogen pulverization is subjected to jet milling at a pressure of 0.4 MPa in an atmosphere having an oxidizing gas content of 100 ppm or less to obtain a fine powder, and the average particle size of the fine powder is 3.5 ⁇ m.
  • Oxidizing gas refers to oxygen or moisture.
  • Methyl octanoate was added to the powder after the jet mill pulverization, and the methyl octanoate was added in an amount of 0.2% by weight of the mixed powder, followed by thorough mixing with a V-type mixer.
  • Magnetic field forming process Using a right-angle oriented magnetic field forming machine, the above-mentioned methyl octanoate-added powder was once formed into a cube having a side length of 25 mm in a 1.8 T orientation magnetic field at a molding pressure of 0.2 ton/cm 2 . Demagnetization after one forming.
  • the machine performs secondary forming.
  • each formed body is moved to a sintering furnace for sintering, and the sintering is maintained at a temperature of 200 ° C and 900 ° C for 2 hours under a vacuum of 10 -3 Pa, and then sintered at a temperature of 1050 ° C for 2 hours. After the Ar gas was introduced to bring the gas pressure to 0.1 Mpa, it was cooled to room temperature.
  • Heat treatment process The sintered body was heat-treated at a temperature of 620 ° C for 1 hour in high-purity Ar gas, and then cooled to room temperature and taken out.
  • the heat-treated sintered body is processed into A magnet having a thickness of 5 mm has a direction of magnetic field orientation of 5 mm.
  • the O content of the comparative magnet and the example magnet was controlled to be 1000 ppm or less throughout the implementation.
  • the Br When the content of Ho is more than 5% by weight, the Br may be lowered, and the hydrogen cracking treatment effect of the quenched alloy sheet is deteriorated, thereby causing a large number of abnormally large particles in the process of pulverizing and pulverizing, and these abnormally large particles are generated.
  • AGG is also formed during the sintering process.
  • the sintered magnet prepared in Example 2 was subjected to FE-EPMA (Field Emission Electron Probe Microanalysis) [JEOL, 8530F], and the results are shown in Fig. 1. It can be observed that the W is rich. The pinning and precipitation in the opposite grain boundary prevents the generation of AGG, and since the relationship between Ho and W is like the relationship between water and oil, they are mutually exclusive and cannot coexist. Thus, the rich Ho phase enters the main phase and forms. Ho 2 Fe 14 B, and the formation of Ho 2 Fe 14 B can increase the anisotropy field of the magnet. Thus, both the coercive force and the anisotropy field of the magnet are significantly improved by the combination of the grain boundary W-rich phase and the main phase rich Ho phase.
  • FE-EPMA Field Emission Electron Probe Microanalysis
  • the crystal grain boundary of the rare earth magnet contains a W-rich region of 40 ppm or more and 3000 ppm or less, and the W-rich region accounts for 50% by volume or more of the crystal grain boundary.
  • Nd having a purity of 99.5%, Ho having a purity of 99.9%, Fe-B for industrial use, pure Fe for industrial use, and W having a purity of 99.99% were prepared and prepared in a weight percentage.
  • Each serial number group was prepared according to the elemental composition in Table 4, and 10 Kg of raw materials were weighed and prepared.
  • Smelting process 1 part of the prepared raw material is placed in a crucible made of alumina, and vacuum-smelting is performed in a vacuum induction melting furnace at a temperature of 1500 ° C or lower in a vacuum of 10 -2 Pa.
  • Casting process Ar gas was introduced into a melting furnace after vacuum melting to bring the gas pressure to 48,000 Pa, and then casting was performed by a single roll quenching method to obtain a quenched alloy at a cooling rate of 10 2 ° C / sec to 10 4 ° C / sec.
  • Hydrogen breaking and pulverizing process the hydrogen quenching furnace in which the quenching alloy is placed is evacuated at room temperature, and then hydrogen gas having a purity of 99.5% is introduced into the hydrogen breaking furnace to a pressure of 0.09 MPa, and after standing for 2 hours, the temperature is raised while vacuuming. The vacuum was evacuated at a temperature of 540 ° C for 2 hours, and then cooled, and hydrogen was taken out to break the pulverized powder.
  • the sample after the hydrogen pulverization is subjected to jet milling and pulverization under a pressure of a pulverization chamber pressure of 0.45 MPa in an atmosphere having an oxidizing gas content of 100 ppm or less to obtain a fine powder and an average of fine powder.
  • the particle size was 3.6 ⁇ m.
  • Oxidizing gas refers to oxygen or moisture.
  • Methyl octanoate was added to the powder after the jet mill pulverization, and the methyl octanoate was added in an amount of 0.2% by weight of the mixed powder, followed by thorough mixing with a V-type mixer.
  • Magnetic field forming process Using a right-angle oriented magnetic field forming machine, the above-mentioned methyl octanoate-added powder was once formed into a cube having a side length of 25 mm in a 1.8 T orientation magnetic field at a molding pressure of 0.2 ton/cm 2 . After the primary molding, the magnetic body is demagnetized, the molded body is taken out from the space, and another magnetic field is applied to the molded body, and the magnetic powder adhering to the surface of the molded body is subjected to the second demagnetization treatment.
  • each formed body is moved to a sintering furnace for sintering, and the sintering is maintained at a temperature of 200 ° C and 700 ° C for 2 hours under a vacuum of 10 -3 Pa, and then sintered at a temperature of 1050 ° C for 2 hours, followed by After the Ar gas was introduced to bring the gas pressure to 0.1 MPa, it was cooled to room temperature.
  • Heat treatment process The sintered body was heat-treated at a temperature of 600 ° C for 1 hour in high-purity Ar gas, and then cooled to room temperature and taken out.
  • the heat-treated sintered body is processed into A magnet having a thickness of 5 mm has a direction of magnetic field orientation of 5 mm.
  • the crystal grain boundary of the rare earth magnet contains a W-rich region of 40 ppm or more and 3,000 ppm or less, and the W-rich region accounts for 50% by volume or more of the crystal grain boundary.
  • the O content of the comparative magnet and the example magnet was controlled at 1000 ppm throughout the implementation. under.
  • FE-EPMA detection was carried out on Examples 1, 2, 3 and 4, and it was also observed that the W-rich phase was pinned out to the grain boundary, and the grain boundary was pinned, thereby preventing the generation of AGG.
  • the Ho phase enters the main phase, forming Ho 2 Fe 14 B, which increases the anisotropy field of the magnet.
  • Each serial number group was prepared according to the elemental composition in Table 6, and 10 Kg of raw materials were weighed and prepared separately.
  • Smelting process 1 part of the prepared raw material is placed in a crucible made of alumina, and vacuum-smelting is performed in a vacuum induction melting furnace at a temperature of 1500 ° C or lower in a vacuum of 10 -2 Pa.
  • Casting process Ar gas was introduced into a melting furnace after vacuum melting to bring the gas pressure to 45,000 Pa, and then casting was performed by a single roll quenching method to obtain a quenched alloy at a cooling rate of 10 2 ° C / sec to 10 4 ° C / sec.
  • Hydrogen breaking pulverization process the hydrogen-dissolving furnace in which the quenching alloy is placed is evacuated at room temperature, and then the hydrogen is broken. A hydrogen gas having a purity of 99.5% was introduced into the furnace to a pressure of 0.085 MPa, and after standing for 2 hours, the temperature was raised while evacuating, and the temperature was raised at 540 ° C for 2 hours, followed by cooling, and the powder after the pulverization was taken out by hydrogen.
  • the sample after the hydrogen pulverization was subjected to jet milling at a pressure of a pulverization chamber pressure of 0.4 MPa in an atmosphere having an oxidizing gas content of 100 ppm or less to obtain a fine powder, and the average particle size of the fine powder was 3.2 ⁇ m.
  • Oxidizing gas refers to oxygen or moisture.
  • Methyl octanoate was added to the powder after the jet mill pulverization, and the methyl octanoate was added in an amount of 0.2% by weight of the mixed powder, followed by thorough mixing with a V-type mixer.
  • Magnetic field forming process Using a right-angle oriented magnetic field forming machine, the above-mentioned methyl octanoate-added powder was once formed into a cube having a side length of 25 mm in a 1.8 T orientation magnetic field at a molding pressure of 0.2 ton/cm 2 . After the primary molding, the magnetic body is demagnetized, the molded body is taken out from the space, and another magnetic field is applied to the molded body, and the magnetic powder adhering to the surface of the molded body is subjected to the second demagnetization treatment.
  • each formed body is moved to a sintering furnace for sintering, and the sintering is maintained at a temperature of 200 ° C and 700 ° C for 2 hours under a vacuum of 10 -3 Pa, and then sintered at a temperature of 1040 ° C for 2 hours, and then passed through. After the Ar gas was introduced to bring the gas pressure to 0.1 MPa, it was cooled to room temperature.
  • Heat treatment process The sintered body was heat-treated at a temperature of 600 ° C for 1 hour in high-purity Ar gas, and then cooled to room temperature and taken out.
  • the heat-treated sintered body is processed into A magnet having a thickness of 5 mm has a direction of magnetic field orientation of 5 mm.
  • the crystal grain boundary of the rare earth magnet contains a W-rich region of 40 ppm or more and 3,000 ppm or less, and the W-rich region accounts for 50% by volume or more of the crystal grain boundary.
  • the O content of the comparative magnet and the example magnet was controlled to be 1000 ppm or less throughout the implementation.
  • FE-EPMA detection was carried out on Examples 1, 2, 3 and 4, and it was also observed that the W-rich phase was pinned out to the grain boundary, and the grain boundary was pinned, thereby preventing the generation of AGG.
  • the Ho phase enters the main phase, forming Ho 2 Fe 14 B, which increases the anisotropy field of the magnet.
  • Each serial number group was prepared according to the elemental composition in Table 8, and 10 kg of raw materials were weighed and prepared.
  • Smelting process 1 part of the prepared raw material is placed in a crucible made of alumina, and vacuum-smelting is performed in a vacuum induction melting furnace at a temperature of 1500 ° C or lower in a vacuum of 10 -2 Pa.
  • Casting process Ar gas is introduced into the melting furnace after vacuum melting to bring the gas pressure to 60,000 Pa, and then cast by a single roll quenching method to obtain a quenched alloy at a cooling rate of 10 2 ° C / sec to 10 4 ° C / sec. The quenched alloy was subjected to heat treatment at 700 ° C for 5 hours, and then cooled to room temperature.
  • Hydrogen breaking pulverization process a hydrogen-breaking furnace in which a quenching alloy is placed is evacuated at room temperature, and then a hydrogen gas having a purity of 99.5% is introduced into a hydrogen-breaking furnace to a pressure of 0.1 MPa, and after standing for 2 hours, the temperature is raised while evacuating. The vacuum was evacuated at a temperature of 540 ° C for 2 hours, and then cooled, and hydrogen was taken out to break the pulverized powder.
  • the sample after the hydrogen pulverization was subjected to jet milling at a pressure of a pulverization chamber pressure of 0.5 MPa in an atmosphere having an oxidizing gas content of 100 ppm or less to obtain a fine powder, and the average particle size of the fine powder was 3.7 ⁇ m.
  • Oxidizing gas refers to oxygen or moisture.
  • Methyl octanoate was added to the powder after the jet mill pulverization, and the methyl octanoate was added in an amount of 0.15% by weight of the mixed powder, followed by thorough mixing with a V-type mixer.
  • Magnetic field forming process Using a right-angle oriented magnetic field forming machine, the above-mentioned methyl octanoate-added powder was once formed into a cube having a side length of 25 mm in a 1.8 T orientation magnetic field at a molding pressure of 0.2 ton/cm 2 . After the primary molding, the magnetic body is demagnetized, the molded body is taken out from the space, and another magnetic field is applied to the molded body, and the magnetic powder adhering to the surface of the molded body is subjected to the second demagnetization treatment.
  • each formed body is moved to a sintering furnace for sintering, and the sintering is maintained at a temperature of 200 ° C and 900 ° C for 2 hours under a vacuum of 10 -3 Pa, and then sintered at a temperature of 1020 ° C for 2 hours, and then passed through.
  • the Ar gas was introduced to bring the gas pressure to 0.1 MPa, it was cooled to room temperature.
  • Heat treatment process The sintered body was heat-treated at a temperature of 550 ° C for 1 hour in high-purity Ar gas, and then cooled to room temperature and taken out.
  • the heat-treated sintered body is processed into A magnet having a thickness of 5 mm has a direction of magnetic field orientation of 5 mm.
  • the crystal grain boundary of the rare earth magnet contains a W-rich region of 40 ppm or more and 3,000 ppm or less, and the W-rich region accounts for 50% by volume or more of the crystal grain boundary.
  • the O content of the comparative magnet and the example magnet was controlled to be 1000 ppm or less throughout the implementation.
  • FE-EPMA detection was carried out on Examples 1, 2, 3 and 4, and it was also observed that the W-rich phase was pinned out to the grain boundary, and the grain boundary was pinned, thereby preventing the generation of AGG.
  • the Ho phase enters the main phase, forming Ho 2 Fe 14 B, which increases the anisotropy field of the magnet.
  • the rare earth magnet containing Ho and W is mainly composed of a W-rich grain boundary phase and a Ho-rich main phase, and suppresses grain growth of the Ho-containing magnet during sintering by a trace amount of W, thereby preventing AGG from occurring in the Ho-containing magnet.
  • a magnet with high coercivity and high heat resistance is obtained, which has good industrial applicability.

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Abstract

本发明公开了一种含有Ho和W的稀土磁铁，所述稀土磁铁含有R2Fe14B型主相，并包括如下的原料成分：R：28wt％～33wt％，R为包括Nd和Ho的稀土元素，其中，Ho的含量为0.3wt％～5wt％，B：0.8wt％～1.3wt％，W：0.0005wt％～0.03wt％，以及余量为T和不可避免的杂质，所述T为主要包括Fe和/或Co的元素。该稀土磁铁主要由富W晶界相和富Ho主相组成，由微量W来抑制含Ho磁铁在烧结过程中的晶粒成长，从而阻止含Ho磁铁发生AGG，得到高矫顽力、高耐热性的磁铁。

Description

一种含有Ho和W的稀土磁铁 技术领域
本发明涉及磁铁的制造技术领域，特别是一种含有Ho和W的稀土磁铁。
背景技术
烧结Nd‐Fe‐B系磁体具有优越的磁性能，在风力发电、核磁共振、汽车工业、计算机、航空航天、家用电器等方面获得广泛应用，而这导致作为烧结Nd‐Fe‐B系磁体主要原材料的Nd消耗过大。而Ho的存在量大，选择Ho部分替代磁铁中的金属Nd，对实现稀土资源的综合利用，具有重要意义。同时，由于Ho可以显著改善Nd‐Fe‐B系磁体的矫顽力、温度稳定性等性能，选择工业生产中较易获得的低价材料Ho部分替代磁铁中的金属Nd，可以降低高性能稀土磁体的综合生产成本。
李峰等在《添加Gd或Ho对烧结Nd‐Fe‐B磁体结构与性能的影响》(粉末冶金工业，第21卷第5期，2011年10月)中描述到，添加Ho能显著改善材料的温度稳定性，较大幅度提高其内禀矫顽力，但剩磁有所下降，J‐H退磁曲线方形度有了明显的提高，并在一定程度上细化了磁体晶粒，使富Nd相分布均匀，减少了空洞等缺陷，使磁体更加致密。
刘湘涟在《添加Ho对烧结Nd‐Fe‐B永磁材料磁性能与温度稳定性的影响》(磁性材料与器件，2011年8月)中描述到，适量Ho元素添加，可抑制Nd‐Fe‐B合金铸锭中a‐Fe相的形成，促进Nd2Fe14B柱状晶的生长，使富Nd相分布比较均匀，使烧结Nd‐Fe‐B磁体具有比较高的致密化程度与良好的显微组织；另外，一定量的Ho添加可以提高内禀矫顽力，并改善磁铁的温度稳定性。张时茂等也在《添加Gd、Ho对烧结Nd‐Fe‐B磁体结构与性能的影响》(稀土，第34卷第1期，2013年2月)中描述到相似内容。
综合以上内容，可以得出，在向磁铁中添加Ho之后，可以细化磁体晶粒， 使富Nd相分布均匀，改善磁铁烧结性能。
另一方面，Nd‐Fe‐B系烧结磁铁的制造方法是逐渐改进的，举例来说，我国国内是从2005年以后，开始普及甩带片(SC法)的，2010年才正式量产。采用SC法将原料溶解铸造后就很容易制造出薄板合金，薄板合金内的结晶组织比较均一、细微，富Nd相也以μm为单位均一分布，将SC法与氢破法进行组合，可以得到平均粒径在10μm以下的细微粉末，同样可以显著地改善磁铁的烧结性能。
然而，对于烧结性能急剧改善的稀土磁铁而言，若是仅仅依靠结晶晶界中少量存在的杂质来抑制晶粒异常长大，极容易发生晶粒异常长大(AGG)。
发明内容
本发明的目的在于克服现有技术之不足，提供一种含有Ho和W的稀土磁铁，该稀土磁铁中，由微量W来抑制含Ho磁铁在烧结过程中的晶粒成长，从而阻止含Ho磁铁发生AGG，得到高矫顽力、高耐热性的磁铁。
本发明提供的技术方式如下：
一种含有Ho和W的稀土磁铁，所述稀土磁铁含有R2Fe14B型主相，并包括如下的原料成分：
R：28wt％～33wt％，R为包括Nd和Ho的稀土元素，其中，Ho的含量为0.3wt％～5wt％，
B：0.8wt％～1.3wt％，
W：0.0005wt％～0.03wt％，
以及余量为T和不可避免的杂质，所述T为主要包括Fe和0～18wt％Co的元素。
本发明中提及的稀土元素包括钇元素在内。
Ho元素可使稀土磁铁的富Nd相分布均匀，从而改进磁铁的烧结性能，但对于烧结性能显著提高的稀土磁铁而言，极容易发生晶粒异常长大(AGG)，因 此，在本发明中，选择使用微量W来抑制晶粒异常长大(AGG)，由于W与主要构成元素的稀土元素、铁、硼的离子半径及电子构造不同，所以，R2Fe14B主相中几乎不存在W，微量W在熔融液的冷却过程中随着R2Fe14B主相的析出进行钉扎(Pinning effect)析出，钉扎晶界的迁移，从而阻止含Ho磁铁在烧结过程中发生AGG，得到高矫顽力、高耐热性的磁铁。
另外，由于W为硬质元素，可使软质晶界相硬化，发挥润滑作用，同样起到了提高取向度的效果。
在目前所采用的稀土磁铁制备方法中，有采用电解槽，圆桶形石墨坩埚作阳极，坩埚轴线上配置钨(W)棒做阴极，且石墨坩埚底部用钨坩埚收集稀土金属的方式，在上述制备稀土元素(如Nd)的过程中，不可避免有少量W混入其中。当然，也可以使用钼(Mo)等其他高熔点金属做阴极，同时使用钼坩埚收集稀土金属的方式，获得完全不含W的稀土元素。
因此，在本发明中，W可以是原料金属(如纯铁、稀土金属、B等)等的杂质，并根据原料中杂质的含量来选定本发明所使用的原料，当然，也可以选择不含有W的原料，而采用加入本发明所描述的添加W金属原料的方式。简而言之，只要稀土磁铁原料中含有必要量的W即可，不管W的来源为何。表1中举例显示了不同产地不同工场的金属Nd中的W元素含量。
表1 不同产地不同工场的金属Nd的W元素含量
Figure PCTCN2016078412-appb-000001
表1中的2N5所代表的含义为99.5％。
需要说明的是，本发明中提及的R：28wt％～33wt％、B：0.8wt％～1.3wt％的含量范围为本行业的常规选择，因此，在实施例中，没有对R、B的含量范围加以试验和验证。
在推荐的实施方式中，T包括2.0wt％以下的选自Sn、Sb、Hf、Bi、V、Zr、Mo、Zn、Ga、Nb、Ni、Ti、Cr、Si、Mn、S或P中的至少一种元素、0.8wt％以下的Cu、0.8wt％以下的Al、以及余量Fe。
在推荐的实施方式中，所述稀土磁铁由如下的步骤制得：将所述稀土磁铁原料成分熔融液制备成稀土磁铁用合金的工序，所述稀土磁铁用合金是将原料合金熔融液用带材铸件法，以102℃/秒以上、104℃/秒以下的冷却速度冷却得到的；将所述稀土磁铁用合金粗粉碎后再通过微粉碎制成细粉的工序；将所述细粉用磁场成形法获得成形体，并在真空或惰性气体中对所述成形体进行烧结，获得氧含量在1000ppm以下的烧结稀土磁铁的工序。
另外，本发明选择在低氧环境中完成磁铁的全部制造工序，使O含量控制在一低水平，一般而言，具有较高氧含量(1000ppm以上)的稀土磁铁可以减少AGG的产生，而较低氧含量(1000ppm以下)的稀土磁铁虽然具有很好的磁性能，却容易产生AGG，而本发明通过添加极微量的W，在低氧含量磁铁中也同样实现了减少AGG的效果。
需要说明的是，由于磁铁的低氧制造工序已是现有技术，且本发明的所有实施例全部采用低氧制造方式，在此不再予以详细描述。
在推荐的实施方式中，所述稀土磁铁用合金是将原料合金熔融液用带材铸件法，以102℃/秒以上、104℃/秒以下的冷却速度冷却得到的，所述粗粉碎为所述稀土磁铁用合金吸氢破碎得到粗粉的工序，所述微粉碎为对所述粗粉进行气流粉碎的工序。
使用带材铸件法(SC法)和氢破法联合处理获得粉末，进一步改善富Nd相分散性能，而W的存在，同样可以阻止经过上述工序制得的含Ho粉末在烧结 过程中发生AGG，获得烧结性良好、矫顽力(Hcj)、方形度(SQ)和耐热性较高的磁铁。
在推荐的实施方式中，所述稀土磁铁为Nd‐Fe‐B系烧结磁铁。
在推荐的实施方式中，所述稀土磁铁的结晶晶界中含有40ppm以上、3000ppm以下的富W区域，所述富W区域占所述结晶晶界的至少50体积％。微量W在熔融液的冷却过程中随着R2Fe14B主相的析出进行钉扎(Pinning effect)析出，并在晶界中富集，从而充分发挥其作用。
在推荐的实施方式中，T包括0.1wt％～0.8wt％的Cu，分布在晶界中的Cu增加了低熔点液相，低熔点液相的增加改善了W的分布，本发明中，W在晶界中分布相当均匀，且分布范围超过富Nd相的分布范围，基本包覆了整个富Nd相，可以认为是W发挥钉扎效果、阻碍晶粒长大的证据，在添加了适量Cu之后，含Ho磁铁在烧结过程中发生AGG的现象进一步减少。
在推荐的实施方式中，T还包括0.1wt％～0.8wt％的Al，Al的添加使合金晶粒细化，同时使富Nd相和富B相的单个区域体积变小，部分Al进入富Nd相与Cu共同作用，改善富Nd相与主相之间的浸润角，使富Nd相和W极为均匀地沿边界分布，减少AGG发生。
在推荐的实施方式中，T还包括选自Sn、Sb、Hf、Bi、V、Zr、Mo、Zn、Ga、Nb、Ni、Ti、Cr、Si、Mn、S或P中的至少一种元素，以上元素的总组成为稀土磁铁成分的0.1wt％～2.0wt％。
在推荐的实施方式中，所述稀土磁铁由包括富W晶界相和富Ho主相的至少2种相组成。
本发明中涉及的所有数值范围包括这一范围内的所有点值。
与现有技术相比，本发明具有如下的特点：
1)由于W与主要构成元素的稀土元素、铁、硼的离子半径及电子构造不同，所以，R2Fe14B主相中几乎不存在W，W在熔融液的冷却过程中，随着R2Fe14B 主相的析出，向晶界中进行钉扎析出，形成富W相，从而防止AGG的产生，而由于Ho与W的关系就像水与油的关系一样，相互排斥，不能共存，因此，富Ho相会进入到主相中，形成Ho2Fe14B(R2Fe14B的各向异性场的强度如下：Gd<Nd<Pr《Ho<Dy《Tb)，可见，Ho2Fe14B的形成可以提高磁铁的各向异性场。由此，在晶界富W相和主相富Ho相的共同作用下，磁铁矫顽力和各向异性场均得以显著提高。
2)由于W为硬质元素，可使软质晶界相硬化，起到润滑剂的效果，提高取向度。
3)添加有Al、Cu的实施方式中，可以使富Nd相和W极为均匀地沿边界分布，减少AGG发生。
4)Ho的存在量大，为工业生产中可以获得的相对低价材料，本发明选择用Ho来部分替代磁铁中的金属Nd，具有综合经济效果高、工业价值高的特点。
附图说明
图1为实施例一的实施例2的烧结磁体的EPMA检测结果。
具体实施方式
以下结合实施例对本发明作进一步详细说明。
实施例一至实施例四所获得的烧结磁铁均使用如下的检测方式测定。
磁性能评价过程：烧结磁铁使用中国计量院的NIM‐10000H型BH大块稀土永磁无损测量系统进行磁性能检测。
磁通衰减率的测定：烧结磁铁置于180℃环境中保温30min，然后再自然冷却降温到室温，测量磁通，测量的结果和加热前的测量数据比较，计算加热前和加热后的磁通衰减率。
AGG的测定：将烧结磁铁沿水平方向抛光，每1cm2所包括的平均AGG数量，本发明中提及的AGG为粒径超过40μm的晶粒。
实施例一
在原料配制过程：准备纯度99.5％的Nd、纯度99.9％的Ho、工业用Fe‐B、工业用纯Fe、纯度99.5％的Cu、Al和纯度99.99％的W，以重量百分比wt％配制。
各元素的含量如表2所示：
表2 各元素的配比
Figure PCTCN2016078412-appb-000002
各序号组按照表2中元素组成进行配制，分别称量、配制了10Kg的原料。
熔炼过程：每次取1份配制好的原料放入氧化铝制的坩埚中，在真空感应熔炼炉中在10‐2Pa的真空中以1600℃以下的温度进行真空熔炼。
铸造过程：在真空熔炼后的熔炼炉中通入Ar气体使气压达到5.5万Pa后，使用单辊急冷法进行铸造，以102℃/秒～104℃/秒的冷却速度获得急冷合金。
氢破粉碎过程：在室温下将放置急冷合金的氢破用炉抽真空，而后向氢破用炉内通入纯度为99.5％的氢气至压力0.09MPa，放置2小时后，边抽真空边升温，在500℃的温度下抽真空1.5小时，之后进行冷却，取出氢破粉碎后的粉末。
微粉碎工序：在氧化气体含量100ppm以下的气氛下，在粉碎室压力为0.4Mpa的压力下对氢破粉碎后的试料进行气流磨粉碎，得到细粉，细粉的平均粒度为3.5μm。氧化气体指的是氧或水分。
在气流磨粉碎后的粉末中添加辛酸甲酯，辛酸甲酯的添加量为混合后粉末重量的0.2％，再用V型混料机充分混合。
磁场成形过程：使用直角取向型的磁场成型机，在1.8T的取向磁场中，在0.2ton/cm2的成型压力下，将上述添加了辛酸甲酯的粉末一次成形成边长为25mm的立方体，一次成形后退磁。
为使一次成形后的成形体不接触到空气，将其进行密封，再使用二次成形 机(等静压成形机)进行二次成形。
烧结过程：将各成形体搬至烧结炉进行烧结，烧结在10‐3Pa的真空下，在200℃和900℃的温度下各保持2小时后，以1050℃的温度烧结2小时，之后通入Ar气体使气压达到0.1Mpa后，冷却至室温。
热处理过程：烧结体在高纯度Ar气中，以620℃温度进行1小时热处理后，冷却至室温后取出。
加工过程：经过热处理的烧结体加工成
Figure PCTCN2016078412-appb-000003
厚度5mm的磁铁，5mm方向为磁场取向方向。
实施例和比较例的磁铁的评价结果如表3中所示：
表3 实施例和比较例的磁性能评价情况
Figure PCTCN2016078412-appb-000004
在整个实施过程中，将对比例磁铁和实施例磁铁的O含量控制在1000ppm以下。
从对比例与实施例可以看到，在Ho的含量小于0.3wt％之时，产生了大量AGG。
而在Ho的含量大于5wt％之时，则可导致Br降低，且急冷合金片的氢破处理效果变差，进而导致气流磨粉碎的过程中产生了大量的异常大颗粒，而这些异常大颗粒在烧结过程中同样形成了AGG。
对实施例2制成的烧结磁铁进行FE‐EPMA(场发射电子探针显微分析)【日本电子株式会社(JEOL)，8530F】检测，结果如图1中所示，可以观察到，富W相向晶界中进行钉扎析出，从而防止AGG的产生，而由于Ho与W的关系就像水与油的关系一样，相互排斥，不能共存，由此，富Ho相进入到主相中，形成Ho2Fe14B，而Ho2Fe14B的形成可以提高磁铁的各向异性场。由此，在晶界富W相和主相富Ho 相的共同作用下，磁铁矫顽力和各向异性场均得以显著提高。
同样地，对实施例1、3和4进行FE‐EPMA检测，同样可以观察到，富W相向晶界中进行钉扎析出，钉扎晶界的迁移，从而防止AGG的产生，而富Ho相进入到主相中，形成Ho2Fe14B，提高磁铁的各向异性场。
此外，实施例1至实施例4中，稀土磁铁的结晶晶界中含有40ppm以上、3000ppm以下的富W区域，该富W区域占结晶晶界的50体积％以上。
实施例二
在原料配制过程：准备纯度99.5％的Nd、纯度99.9％的Ho、工业用Fe‐B、工业用纯Fe、和纯度99.99％的W，以重量百分比来配制。
各元素的含量如表4所示：
表4 各元素的配比
Figure PCTCN2016078412-appb-000005
各序号组按照表4中元素组成进行配制，分别称量、配制了10Kg的原料。
熔炼过程：每次取1份配制好的原料放入氧化铝制的坩埚中，在真空感应熔炼炉中在10‐2Pa的真空中以1500℃以下的温度进行真空熔炼。
铸造过程：在真空熔炼后的熔炼炉中通入Ar气体使气压达到4.8万Pa后，使用单辊急冷法进行铸造，以102℃/秒～104℃/秒的冷却速度获得急冷合金。
氢破粉碎过程：在室温下将放置急冷合金的氢破用炉抽真空，而后向氢破用炉内通入纯度为99.5％的氢气至压力0.09MPa，放置2小时后，边抽真空边升温，在540℃的温度下抽真空2小时，之后进行冷却，取出氢破粉碎后的粉末。
微粉碎工序：在氧化气体含量100ppm以下的气氛下，在粉碎室压力为0.45MPa的压力下对氢破粉碎后的试料进行气流磨粉碎，得到细粉，细粉的平均 粒度为3.6μm。氧化气体指的是氧或水分。
在气流磨粉碎后的粉末中添加辛酸甲酯，辛酸甲酯的添加量为混合后粉末重量的0.2％，再用V型混料机充分混合。
磁场成形过程：使用直角取向型的磁场成型机，在1.8T的取向磁场中，在0.2ton/cm2的成型压力下，将上述添加了辛酸甲酯的粉末一次成形成边长为25mm的立方体，一次成形后退磁，将成形体从空间取出，再向成形体施加另一磁场，对附着在成形体表面的磁粉进行第二次退磁处理。
为使一次成形后的成形体不接触到空气，将其进行密封，再使用二次成形机(等静压成形机)进行二次成形。
烧结过程：将各成形体搬至烧结炉进行烧结，烧结在10‐3Pa的真空下，在200℃和700℃的温度下各保持2小时后，以1050℃的温度烧结2小时，之后通入Ar气体使气压达到0.1MPa后，冷却至室温。
热处理过程：烧结体在高纯度Ar气中，以600℃温度进行1小时热处理后，冷却至室温后取出。
加工过程：经过热处理的烧结体加工成
Figure PCTCN2016078412-appb-000006
厚度5mm的磁铁，5mm方向为磁场取向方向。
实施例和比较例的磁铁的评价结果如表5中所示：
表5 实施例和对比例的磁性能评价情况
Figure PCTCN2016078412-appb-000007
经检测，实施例1至实施例4中，稀土磁铁的结晶晶界中含有40ppm以上、3000ppm以下的富W区域，该富W区域占结晶晶界的50体积％以上。
在整个实施过程中，将对比例磁铁和实施例磁铁的O含量控制在1000ppm以 下。
从对比例与实施例可以看到，在W的含量小于5ppm之时，W的分布不足，晶界中没有足量的阻止晶粒成长的物质，产生大量的AGG。
而在W的含量大于300ppm之时，会产生一部分的WB2相，可导致Br降低，急冷合金片的氢破处理效果变差，进而导致气流磨粉碎的过程中产生了大量的异常大颗粒，而这些异常大颗粒在烧结过程中同样形成了AGG。
同样地，对实施例1、2、3和4进行FE‐EPMA检测，同样可以观察到，富W相向晶界中进行钉扎析出，钉扎晶界的迁移，从而防止AGG的产生，而富Ho相进入到主相中，形成Ho2Fe14B，提高磁铁的各向异性场。
实施例三
在原料配制过程：准备纯度99.5％的Nd、纯度99.9％的Ho、工业用Fe‐B、工业用纯Fe、纯度99.99％的W、和纯度99.5％的Zr、Ga、Nb、Mn、Si、Cr、Cu、Mo，以重量百分比来配制。
各元素的含量如表6所示：
表6 各元素的配比
Figure PCTCN2016078412-appb-000008
各序号组按照表6中元素组成进行配制，分别称量、配制了10Kg的原料。
熔炼过程：每次取1份配制好的原料放入氧化铝制的坩埚中，在真空感应熔炼炉中在10‐2Pa的真空中以1500℃以下的温度进行真空熔炼。
铸造过程：在真空熔炼后的熔炼炉中通入Ar气体使气压达到4.5万Pa后，使用单辊急冷法进行铸造，以102℃/秒～104℃/秒的冷却速度获得急冷合金。
氢破粉碎过程：在室温下将放置急冷合金的氢破用炉抽真空，而后向氢破 用炉内通入纯度为99.5％的氢气至压力0.085MPa，放置2小时后，边抽真空边升温，在540℃的温度下抽真空2小时，之后进行冷却，取出氢破粉碎后的粉末。
微粉碎工序：在氧化气体含量100ppm以下的气氛下，在粉碎室压力为0.4MPa的压力下对氢破粉碎后的试料进行气流磨粉碎，得到细粉，细粉的平均粒度为3.2μm。氧化气体指的是氧或水分。
在气流磨粉碎后的粉末中添加辛酸甲酯，辛酸甲酯的添加量为混合后粉末重量的0.2％，再用V型混料机充分混合。
磁场成形过程：使用直角取向型的磁场成型机，在1.8T的取向磁场中，在0.2ton/cm2的成型压力下，将上述添加了辛酸甲酯的粉末一次成形成边长为25mm的立方体，一次成形后退磁，将成形体从空间取出，再向成形体施加另一磁场，对附着在成形体表面的磁粉进行第二次退磁处理。
为使一次成形后的成形体不接触到空气，将其进行密封，再使用二次成形机(等静压成形机)进行二次成形。
烧结过程：将各成形体搬至烧结炉进行烧结，烧结在10‐3Pa的真空下，在200℃和700℃的温度下各保持2小时后，以1040℃的温度烧结2小时，之后通入Ar气体使气压达到0.1MPa后，冷却至室温。
热处理过程：烧结体在高纯度Ar气中，以600℃温度进行1小时热处理后，冷却至室温后取出。
加工过程：经过热处理的烧结体加工成
Figure PCTCN2016078412-appb-000009
厚度5mm的磁铁，5mm方向为磁场取向方向。
实施例和比较例的磁铁的评价结果如表7中所示：
表7 实施例和对比例的磁性能评价情况
Figure PCTCN2016078412-appb-000010
Figure PCTCN2016078412-appb-000011
经检测，实施例1至实施例4中，稀土磁铁的结晶晶界中含有40ppm以上、3000ppm以下的富W区域，该富W区域占结晶晶界的50体积％以上。
在整个实施过程中，将对比例磁铁和实施例磁铁的O含量控制在1000ppm以下。
从对比例与实施例可以看到，在Cu的含量小于0.1wt％之时，由于原料的纯度高、杂质少，以致形成了少量AGG。
而在Cu的含量大于0.8wt％之时，会导致磁铁Br降低，且由于Cu是低熔点元素，可导致AGG的大量发生。
同样地，对实施例1、2、3和4进行FE‐EPMA检测，同样可以观察到，富W相向晶界中进行钉扎析出，钉扎晶界的迁移，从而防止AGG的产生，而富Ho相进入到主相中，形成Ho2Fe14B，提高磁铁的各向异性场。
实施例四
在原料配制过程：准备纯度99.5％的Nd、纯度99.9％的Ho、工业用Fe‐B、工业用纯Fe、纯度99.5％的Cu、Al、Zr和纯度99.99％的W，以重量百分比来配制。
各元素的含量如表8所示：
表8 各元素的配比
Figure PCTCN2016078412-appb-000012
各序号组按照表8中元素组成进行配制，分别称量、配制了10Kg的原料。
熔炼过程：每次取1份配制好的原料放入氧化铝制的坩埚中，在真空感应熔炼炉中在10‐2Pa的真空中以1500℃以下的温度进行真空熔炼。
铸造过程：在真空熔炼后的熔炼炉中通入Ar气体使气压达到6万Pa后，使用单辊急冷法进行铸造，以102℃/秒～104℃/秒的冷却速度获得急冷合金，将急冷合金在700℃进行5小时的保温热处理，然后冷却到室温。
氢破粉碎过程：在室温下将放置急冷合金的氢破用炉抽真空，而后向氢破用炉内通入纯度为99.5％的氢气至压力0.1MPa，放置2小时后，边抽真空边升温，在540℃的温度下抽真空2小时，之后进行冷却，取出氢破粉碎后的粉末。
微粉碎工序：在氧化气体含量100ppm以下的气氛下，在粉碎室压力为0.5MPa的压力下对氢破粉碎后的试料进行气流磨粉碎，得到细粉，细粉的平均粒度为3.7μm。氧化气体指的是氧或水分。
在气流磨粉碎后的粉末中添加辛酸甲酯，辛酸甲酯的添加量为混合后粉末重量的0.15％，再用V型混料机充分混合。
磁场成形过程：使用直角取向型的磁场成型机，在1.8T的取向磁场中，在0.2ton/cm2的成型压力下，将上述添加了辛酸甲酯的粉末一次成形成边长为25mm的立方体，一次成形后退磁，将成形体从空间取出，再向成形体施加另一磁场，对附着在成形体表面的磁粉进行第二次退磁处理。
为使一次成形后的成形体不接触到空气，将其进行密封，再使用二次成形机(等静压成形机)进行二次成形。
烧结过程：将各成形体搬至烧结炉进行烧结，烧结在10‐3Pa的真空下，在200℃和900℃的温度下各保持2小时后，以1020℃的温度烧结2小时，之后通入Ar气体使气压达到0.1MPa后，冷却至室温。
热处理过程：烧结体在高纯度Ar气中，以550℃温度进行1小时热处理后，冷却至室温后取出。
加工过程：经过热处理的烧结体加工成
Figure PCTCN2016078412-appb-000013
厚度5mm的磁铁，5mm方向为磁场取向方向。
实施例和对比例的磁铁的评价结果如表9中所示：
表9 实施例和对比例的磁性能评价情况
Figure PCTCN2016078412-appb-000014
经检测，实施例1至实施例4中，稀土磁铁的结晶晶界中含有40ppm以上、3000ppm以下的富W区域，该富W区域占结晶晶界的50体积％以上。
在整个实施过程中，将对比例磁铁和实施例磁铁的O含量控制在1000ppm以下。
从对比例与实施例可以看到，在Al的含量小于0.1wt％之时，由于原料的纯度高、杂质少，以致形成了少量AGG。
而在Al的含量大于0.8wt％之时，过量的Al会导致磁铁Br急速下降，且由于Al是低熔点元素，可导致AGG的大量发生。
同样地，对实施例1、2、3和4进行FE‐EPMA检测，同样可以观察到，富W相向晶界中进行钉扎析出，钉扎晶界的迁移，从而防止AGG的产生，而富Ho相进入到主相中，形成Ho2Fe14B，提高磁铁的各向异性场。
上述实施例仅用来进一步说明本发明几种具体的实施方式，但本发明并不局限于实施例，凡是依据本发明的技术实质对以上实施例所作的任何简单修改、等同变化与修饰，均落入本发明技术方案的保护范围内。
工业实用性
本发明一种含有Ho和W的稀土磁铁，主要由富W晶界相和富Ho主相组成，由微量W来抑制含Ho磁铁在烧结过程中的晶粒成长，从而阻止含Ho磁铁发生AGG，得到高矫顽力、高耐热性的磁铁，具有良好的工业实用性。

Claims (10)

  1. 一种含有Ho和W的稀土磁铁，所述稀土磁铁含有R2Fe14B型主相，其特征在于，包括如下的原料成分：
    R：28wt％～33wt％，R为包括Nd和Ho的稀土元素，其中，Ho的含量为0.3wt％～5wt％，
    B：0.8wt％～1.3wt％，
    W：0.0005wt％～0.03wt％，
    以及余量为T和不可避免的杂质，所述T为主要包括Fe和0～18wt％Co的元素。
  2. 根据权利要求1所述的一种含有Ho和W的稀土磁铁，其特征在于：T包括2.0wt％以下的选自Sn、Sb、Hf、Bi、V、Zr、Mo、Zn、Ga、Nb、Ni、Ti、Cr、Si、Mn、S或P中的至少一种元素、0.8wt％以下的Cu、0.8wt％以下的Al、以及余量Fe。
  3. 根据权利要求2所述的一种含有Ho和W的稀土磁铁，其特征在于，所述稀土磁铁由如下的步骤制得：将所述稀土磁铁原料成分熔融液制备成稀土磁铁用合金的工序；将所述稀土磁铁用合金粗粉碎后再通过微粉碎制成细粉的工序；将所述细粉用磁场成形法获得成形体，并在真空或惰性气体中对所述成形体进行烧结，获得氧含量在1000ppm以下的烧结稀土磁铁的工序。
  4. 根据权利要求3所述的一种含有Ho和W的稀土磁铁，其特征在于：所述稀土磁铁用合金是将原料合金熔融液用带材铸件法，以102℃/秒以上、104℃/秒以下的冷却速度冷却得到的，所述粗粉碎为所述稀土磁铁用合金吸氢破碎得到粗粉的工序，所述微粉碎为对所述粗粉进行气流粉碎的工序。
  5. 根据权利要求1或2或3或4所述的一种含有Ho和W的稀土磁铁，其特征在于：所述稀土磁铁为Nd‐Fe‐B系烧结磁铁。
  6. 根据权利要求5所述的一种含有Ho和W的稀土磁铁，其特征在于：所述稀 土磁铁的结晶晶界中含有40ppm以上、3000ppm以下的富W区域，所述富W区域占所述结晶晶界的至少50体积％。
  7. 根据权利要求5所述的一种含有Ho和W的稀土磁铁，其特征在于：T包括0.1wt％～0.8wt％的Cu。
  8. 根据权利要求5所述的一种含有Ho和W的稀土磁铁，其特征在于：T包括0.1wt％～0.8wt％的Al。
  9. 根据权利要求6所述的一种含有Ho和W的稀土磁铁，其特征在于：T还包括选自Sn、Sb、Hf、Bi、V、Zr、Mo、Zn、Ga、Nb、Ni、Ti、Cr、Si、Mn、S或P中的至少一种元素，以上元素的总组成为稀土磁铁成分的0.1wt％～2.0wt％。
  10. 根据权利要求1所述的一种含有Ho和W的稀土磁铁，其特征在于：所述稀土磁铁由包括富W晶界相和富Ho主相的至少2种相组成。
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US20180061538A1 (en) 2018-03-01

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