WO2014101854A1 - 基于热处理的稀土磁铁用合金粉末和稀土磁铁的制造方法 - Google Patents

基于热处理的稀土磁铁用合金粉末和稀土磁铁的制造方法 Download PDF

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WO2014101854A1
WO2014101854A1 PCT/CN2013/090824 CN2013090824W WO2014101854A1 WO 2014101854 A1 WO2014101854 A1 WO 2014101854A1 CN 2013090824 W CN2013090824 W CN 2013090824W WO 2014101854 A1 WO2014101854 A1 WO 2014101854A1
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heat treatment
rare earth
earth magnet
fine powder
producing
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PCT/CN2013/090824
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English (en)
French (fr)
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永田浩
吴冲浒
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厦门钨业股份有限公司
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Priority to US14/758,699 priority Critical patent/US10242779B2/en
Publication of WO2014101854A1 publication Critical patent/WO2014101854A1/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
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    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
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    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
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    • 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
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    • B22F9/00—Making metallic powder or suspensions thereof
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    • 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
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
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    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
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    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
    • 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
    • H01F1/0536—Alloys characterised by their composition containing rare earth metals sintered
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H01F41/0266—Moulding; Pressing
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    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H01F41/0293—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets
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    • 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
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Definitions

  • the present invention relates to the field of manufacturing technology of magnets, and more particularly to a method for producing an alloy powder for a rare earth magnet based on heat treatment and a method for producing a rare earth magnet.
  • the rare earth magnet is a magnet based on the main phase of the intermetallic compound R 2 T 14 B, wherein R is a rare earth element, T is iron, or a transition metal element replacing a part of iron and iron, and B is boron, which has
  • the operating temperature of rare earth magnets can reach up to 200 degrees Celsius. Excellent performance, and its hard texture, stable performance, good cost performance, and extremely wide application.
  • the manufacturing process of the sintered rare earth magnet mainly includes the following processes: raw material preparation ⁇ melting ⁇ casting ⁇ hydrogen breaking pulverization (HD) ⁇ airflow pulverization (JM) ⁇ magnetic field forming ⁇ sintering ⁇ heat treatment ⁇ magnetic property evaluation ⁇ sintered body Evaluation of oxygen content ⁇ processing ⁇ surface treatment, etc.
  • the development process of increasing the content of the main phase and reducing the composition of the rare earth is not unreasonable.
  • the overall anti-oxidation technology of the manufacturing method is continuously developed.
  • the oxygen content in the sintered magnet can be reduced to below 2,500 ppm.
  • the trace component fluctuates.
  • the influence of unstable factors such as the incorporation of impurities in the process is also increased, which tends to cause over-sintering and abnormal grain growth (AGG), and also causes problems such as coercive force, squareness, and low heat resistance.
  • One of the objects of the present invention is to overcome the deficiencies of the prior art and to provide a method for producing an alloy powder for a rare earth magnet based on heat treatment, which is to increase the heat treatment process of the fine powder before the forming process in the magnetic field after the gas flow grinding and pulverizing step.
  • a method for producing an alloy powder for a rare earth magnet based on heat treatment which is to increase the heat treatment process of the fine powder before the forming process in the magnetic field after the gas flow grinding and pulverizing step.
  • the method for producing an alloy powder for a rare earth magnet based on heat treatment wherein the rare earth magnet is a magnet containing a main phase of R 2 T 14 B, and the R is at least one selected from the group consisting of rare earth elements including a lanthanum element.
  • the T is at least one transition metal element including Fe, and includes the steps of: coarsely pulverizing the rare earth magnet with an alloy, and then finely pulverizing by a jet mill to form a fine powder, which is vacuum or inert
  • the gas atmosphere is obtained by heat treatment at a temperature of 100 ° C to 1000 ° C for 6 minutes or longer and 24 hours or shorter.
  • the temperature of the fine powder heat treatment step is preferably from 300 ° C to 700 ° C.
  • the fine powder in the fine powder heat treatment step, is vibrated or shaken.
  • a furnace such as a rotary furnace for treatment, thereby improving production efficiency.
  • the vacuum state heat treatment step has a pressure of 10 -2 Pa to 500 Pa, an oxygen content of 0.5 ppm to 2000 ppm, and a dew point of -60 ° C to 20 ° C.
  • the invention has undergone a large number of tests to control the content of oxidizing gas (including water and oxygen) in the atmosphere, so that the surface of all the alloy powders can be produced and only a very small amount of oxide layer can be produced, so that the fine powder heat-treated under the above conditions is excellent. Lubricity, and exhibits oxidation resistance in subsequent sintering and heavy rare earth diffusion processes to produce magnets with high coercivity, high squareness, and high heat resistance.
  • the mean free path of the oxidizing gas is inversely proportional to the pressure P according to the formula of the mean free path, and therefore, the probability of the oxidizing gas reacting with the alloy powder is more
  • the powders located in the surface layer, the middle layer and the bottom layer are oxidized to obtain a high performance powder.
  • the inert gas atmosphere heat treatment step has a pressure of 10 -1 Pa to 1000 Pa, an oxygen content of 0.5 ppm to 2000 ppm, and a dew point of -60 ° C to 20 ° C.
  • the effect is the same as the previous paragraph.
  • 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 coarse pulverization step is a step of subjecting the rare earth magnet alloy to hydrogen pulverization under a hydrogen pressure of 0.01 MPa or more and 1 MPa or less for 0.5 to 6 hours, followed by vacuum dehydrogenation.
  • the rare earth magnet alloy is in atomic percent and has a composition of R e T f A g J h G i D k , wherein:
  • R is Nd or contains Nd and at least one selected from the group consisting of La, Ce, Pr, Sm, Gd, Dy, Tb, Ho, Er, Eu, Tm, Lu or Y
  • T is Fe or contains Fe and is selected from Ru At least one of, Co or Ni
  • A is B or contains B and at least one selected from C or P
  • J is at least one selected from the group consisting of Cu, Mn, Si or Cr
  • G is selected from Al At least one of Ga, Ag, Bi or Sn
  • D being at least one selected from the group consisting of Zr, Hf, V, Mo, W, Ti or Nb;
  • the atomic percentage at% of e is 12 ⁇ e ⁇ 16,
  • the atomic percentage at% of g is 5 ⁇ g ⁇ 9,
  • the atomic percentage at% of h is 0.05 ⁇ h ⁇ 1,
  • the atomic percentage at% of i is 0.2 ⁇ i ⁇ 2.0
  • the atomic percentage at% of k is 0 ⁇ j ⁇ 4,
  • O and N are impurities which are easily mixed in the operation process, and O and N may be mixed in a small amount of conventional impurities in the alloy powder.
  • Another object of the present invention is to provide a method of producing a rare earth magnet.
  • the rare earth magnet is a magnet containing a main phase of R 2 T 14 B, and the R is at least one selected from the group consisting of rare earth elements including a lanthanum element, and the T is including Fe.
  • At least one transition metal element characterized by comprising the steps of: coarsely pulverizing the rare earth magnet with an alloy and then finely pulverizing it by a jet mill to form a fine powder, which is 100 in a vacuum or an inert gas atmosphere.
  • the heat treatment is carried out at a temperature of from ° C to 1000 ° C for 6 minutes or more and 24 hours or less, followed by molding by a magnetic field molding method, and sintering at a temperature of 950 ° C to 1140 ° C in a vacuum or an inert gas.
  • the present invention has the following characteristics:
  • the finely pulverized fine powder is heat-treated at a temperature of 100 ° C to 1000 ° C for 6 minutes or more and 24 hours or less, and the powder is subjected to heat treatment to cause a drastic change in the properties of the powder to obtain a high coercive force and a high square shape.
  • the powder can be sintered at a high temperature of 20 to 40 ° C higher than the conventional method, and no abnormal grain growth (AGG) occurs, and the powder after the heat treatment can be in a particularly wide range of sintering temperatures. Sintering can be carried out to expand production conditions.
  • Raw material preparation process preparation of 99.5% purity Nd, Pr, Dy, Tb and Gd, industrial Fe-B, industrial pure Fe, purity 99.99% Co, purity 99.5% Cu, Mn, Al, Ag, Mo and C. It is prepared in terms of atomic percentage at% according to the composition of R e T f A g J h G i D k .
  • Hydrogen pulverization ie, coarse pulverization: a cast piece having an average thickness of 0.3 mm is placed in a stainless steel rotary hydrogen furnace vessel having an inner diameter of ⁇ 1200 mm, and the vessel is evacuated to a vacuum of 10 Pa or less, and then the purity is 99.999% hydrogen to a pressure of 0.12 MPa, the container was rotated at a rotation speed of 1 rpm for 2 hours to absorb hydrogen, and then vacuum-deducted at 600 ° C for 2 hours, and then rotated at a rotation speed of 30 rpm while rotating the container. Take out the cooled coarse powder.
  • Fine pulverization process The coarse powder was finely pulverized using a gas flow fine pulverizer to obtain a fine powder having an average particle diameter of 4.2 ⁇ m.
  • Fine powder heat treatment process the fine powder is divided into equal parts of 8 parts, each of which is placed in a ⁇ 1200mm stainless steel container, and the container is vacuumed to a pressure of 10 -1 Pa, an oxygen content of 1 to 100 ppm, and a dew point of 0 to 10 ° C, after which the stainless steel container was placed in an external heat furnace for heating.
  • the heating temperature and time of each fine powder were as shown in Table 2.
  • the stainless steel container was rotated at a rotation speed of 10 rpm.
  • the container was taken out from the external heat furnace, and while being externally cooled by water, it was rotated at a rotation speed of 20 rpm, and cooled for 3 hours.
  • Forming process in a magnetic field no organic materials such as forming aids and lubricants are added to the fine powder powder after heat treatment, and a right-angle oriented magnetic field forming machine is used, in a 2.1T oriented magnetic field, under a molding pressure of 0.2 ton/cm 2 It is formed into a cube having a side length of 40 mm at one time, and is demagnetized in a magnetic field of 0.2 T after one molding.
  • secondary molding was performed using a secondary molding machine (isostatic pressing machine) under a pressure of 1.2 ton/cm 2 .
  • each formed body is sent to a sintering furnace for sintering, and the sintering is maintained under a vacuum of 10 -3 Pa at 200 ° C and 600 ° C for 2 hours, and then at 1080 ° C in an Ar gas atmosphere of 0.01 MPa.
  • the temperature was sintered for 2 hours, and then Ar gas was introduced to bring the gas pressure to 0.1 MPa, and then 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.
  • 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.
  • Oxygen content evaluation process in the sintered body The oxygen content in the sintered body was measured using an EMGA-620W type oxygen-nitrogen analyzer of HORIBA, Japan.
  • the fine powder activity of forming a uniform oxide film on the surface becomes weak, and in the process of forming to sintering, even if it is exposed to the atmosphere, intense oxidation does not occur, and fine powder which is not subjected to heat treatment is active. It is more likely to be oxidized. In the process of forming to sintering, even if it is only exposed to a little atmosphere, intense oxidation occurs, and the oxygen content of the sintered body becomes high.
  • the heat treatment temperature of the fine powder exceeds 1000 ° C
  • the oxide film formed on the surface of the fine powder particles easily diffuses into the particles, and as a result, the adhesion between the powders becomes higher like that of the non-oxidized film, so that Br (BH)max becomes extremely poor, and grain abnormal growth (AGG) is likely to occur at the time of sintering, and the coercive force Hcj is lowered.
  • Raw material preparation process preparation of 99.9% purity Nd, Y, industrial Fe-B, industrial Fe-P, industrial Fe-Cr, industrial pure Fe, purity 99.9% Ni, Si, purity 99.5% Sn, W.
  • Casting process Ar gas was introduced into the melting furnace after vacuum melting to bring the gas pressure to 50,000 Pa, and then cast into a cast piece having an average thickness of 2 mm in a water-cooled disk-shaped cast sheet.
  • Hydrogen breaking pulverization process The cast piece is placed in a stainless steel rotary hydrogen furnace container with an inner diameter of ⁇ 1200 mm, and the vacuum is evacuated to a vacuum of 10 Pa or less, and then a hydrogen gas having a purity of 99.999% is introduced to a pressure of 0.12 MPa.
  • the rotary hydrogen reactor vessel was rotated at a rotation speed of 1 rpm for 2 hours to absorb hydrogen, and then vacuum-dehydrogenated at a temperature of 600 ° C for 2 hours, and then cooled while rotating the vessel at a rotation speed of 30 rpm, and the cooled coarse powder was taken out. .
  • Fine pulverization process The coarse powder was finely pulverized using a gas flow fine pulverizer to obtain a fine powder having an average particle diameter of 6.8 ⁇ m, which was divided into 6 equal portions.
  • Fine powder heat treatment process 4 parts of the fine powder after air flow pulverization are placed in a ⁇ 1200mm stainless steel container, and the container is vacuumed to a vacuum of 10 -2 Pa, an oxygen content of 0.5 to 50 ppm, and a dew point of 10 to 20 ° C. Then, the container was placed in an external heat furnace for heating; the heating temperature was 600 ° C for 2 hours, and the container was rotated at a rotation speed of 1 rpm when heated.
  • the container was taken out from the external heat furnace, and while being externally cooled by water, it was rotated at a rotation speed of 20 rpm, and cooled for 3 hours.
  • Forming process in a magnetic field 4 parts of the powder after heat treatment of the fine powder and 2 parts of the powder not subjected to the heat treatment of the fine powder are not added with an organic additive, and each uses a right angle oriented type magnetic field forming machine, in a 2T orientation magnetic field, At a molding pressure of 0.20 ton/cm 2 , a cube having a side length of 40 mm was formed at one time; after one molding, the magnetic field was demagnetized in a magnetic field of 0.2 T; in order to seal the molded body after one molding as far as possible without contacting the air, Secondary forming was performed using a secondary molding machine (isostatic press molding machine) under a pressure of 1.2 ton / cm 2 .
  • a secondary molding machine isostatic press molding machine
  • each formed body is sent to a sintering furnace for sintering, and the sintering is carried out under a vacuum of 10 -3 Pa for 2 hours at 300 ° C and 500 ° C, and then sintered at a temperature of 1050 ° C for 6 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 550 ° C for 1 hour in high-purity Ar gas, and then cooled to room temperature and taken out.
  • Two sintered bodies made of unheated powder are processed into magnets of ⁇ 15 mm and thickness of 5 mm, and the direction of 5 mm is the direction of magnetic field orientation.
  • One part of the magnet made of sintered body is directly used as a magnet without grain boundary diffusion treatment.
  • the magnetic properties were measured, and the magnetic properties (Comparative Example 1) were evaluated.
  • the other magnets of the sintered body were washed, and after the surface was cleaned, grain boundary diffusion treatment was carried out according to the method in A in Table 4 (Comparative Example 2).
  • the sintered body made of 4 parts of the heat-treated powder is processed into a magnet having a diameter of 15 mm and a thickness of 5 mm, and a direction of 5 mm is a direction of magnetic field orientation, wherein one part of the magnet made of the sintered body is directly subjected to magnetic property detection as a magnet having no grain boundary diffusion treatment.
  • the magnetic properties were evaluated (Comparative Example 3).
  • the other 3 parts of the sintered body processed by the heat-treated powder are washed, and after the surface is cleaned, the magnets made of each sintered body are respectively A, B, and C in Table 4. Three methods are used for grain boundary diffusion treatment.
  • Table 4 Grain boundary diffusion treatment method Species of grain boundary diffusion Process details A Dy oxide powder, Tb fluoride powder coating diffusion method A 3:1 ratio of Dy oxide and Tb fluoride is sprayed onto the magnet and the coated magnet is dried in high purity Ar Heat treatment at a temperature of 850 °C for 12 hours in a gas atmosphere.
  • C Dy metal vapor diffusion method In a vacuum heat treatment furnace, a Dy metal plate, a Mo mesh, and a magnet are placed together, and steam is treated in an Ar atmosphere at a temperature of 1010 ° C. 6 Hours.
  • 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.
  • Oxygen content evaluation process in the sintered body The oxygen content in the sintered body was measured using an EMGA-620W type oxygen-nitrogen analyzer of HORIBA, Japan.
  • Table 5 shows the evaluation of the magnetic properties and the evaluation of the oxygen content of the examples and comparative examples in the case of the fine powder heat treatment and the grain boundary diffusion treatment.
  • Raw material preparation process preparation of 99.5% purity La, Ce, Nd, Tb, Ho, industrial Fe-B, industrial pure Fe, purity 99.99% Ru, purity 99.5% P, Si, Cr, Ga, Sn, Zr; formulated in atomic percentage at% according to the composition of R e T f A g J h G i D k .
  • La is 0.1, Ce is 0.1, Nd is 12, Tb is 0.2, and Ho is 0.2;
  • Fe is the balance and Ru is 1;
  • P is 0.05 and B is 7;
  • Si is 0.2 and Cr is 0.2;
  • Ga is 0.2 and Sn is 0.1;
  • Zr is 0.5.
  • Casting process Ar gas was introduced into a melting furnace after vacuum melting to bring the gas pressure to 80,000 Pa, and then cast into a cast piece having an average thickness of 0.15 mm by an entrainment casting method (SC).
  • SC entrainment casting method
  • Hydrogen breaking pulverization process the cast piece is placed in a stainless steel rotary hydrogen furnace vessel with an inner diameter of ⁇ 1200 mm, and the vacuum is evacuated to a vacuum of 10 Pa or less, and then a hydrogen gas having a purity of 99.999% is introduced to a pressure of 0.12 MPa.
  • the mixture was rotated at a rotation speed of 1 rpm for 2 hours to absorb hydrogen, and then vacuum-dehydrogenated at a temperature of 600 ° C for 2 hours, and then cooled while rotating the vessel at a rotation speed of 30 rpm, and the cooled coarse powder was taken out.
  • Micro-grinding process finely pulverizing the coarse powder using a gas flow micro-pulverizer to obtain a fine powder having an average particle diameter of 5 ⁇ m;
  • Fine powder heat treatment process The fine powder after airflow pulverization is divided into 6 equal parts, each of which is placed in a stainless steel container of ⁇ 1200 mm, and the container is vacuumed separately to reach a vacuum of 10 Pa or less, and then an Ar gas having a purity of 99.9999% is introduced.
  • the pressure is 500 Pa
  • the control oxygen content is 1800 to 2000 ppm
  • the dew point is -60 ° C to -50 ° C
  • the container is placed in an external heat type furnace for heating, and the container is rotated at a rotation speed of 5 rpm when heated.
  • the heating temperature and time per part are as shown in Table 6.
  • the container was taken out from the external heat furnace, and while being externally cooled by water, it was rotated at a rotation speed of 20 rpm, and cooled for 3 hours.
  • Forming process in a magnetic field The powder after heat treatment of the fine powder is not added with an organic additive, and a magnetic field forming machine of a right angle orientation type is directly used.
  • a magnetic field forming machine of a right angle orientation type In a 1.8T orientation magnetic field, at a molding pressure of 1.2 ton/cm 2 , one molding is performed at a time.
  • the cubes having a side length of 40 mm are demagnetized in a magnetic field of 0.2 T after one molding, and the molded body after the primary molding is sealed as far as possible without coming into contact with air, and is transported to a sintering furnace.
  • each formed body is sent to a sintering furnace for sintering, and the sintering is maintained under a vacuum of 10 -3 Pa at 200 ° C and 600 ° C for 2 hours, and then at 1080 ° C in an Ar gas atmosphere of 0.02 MPa.
  • the temperature was sintered for 2 hours, and then Ar gas was introduced to bring the gas pressure to 0.1 MPa, and then 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.
  • 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, and the average value was evaluated.
  • Oxygen content evaluation process in the sintered body The oxygen content in the sintered body was measured using an EMGA-620W type oxygen-nitrogen analyzer of HORIBA, Japan.
  • Raw material preparation process Preparation of 99.5% purity Lu, Er, Nd, Tm, Y, industrial Fe-B, industrial pure Fe, purity 99.99% Co, purity 99.5% C, Cu, Mn, Ga, Bi, Ti is prepared in atomic percentage at% according to the composition of R e T f A g J h G i D k .
  • Lu is 0.2
  • Er is 0.2
  • Nd is 12
  • Tm is 0.5
  • Y is 0.6;
  • Fe is the balance and Co is 1;
  • C is 0.05 and B is 7;
  • composition J Cu is 0.2 and Mn is 0.2;
  • Ga is 0.2 and Bi is 0.1;
  • Hydrogen breaking pulverization process the cast piece is placed in a stainless steel rotary hydrogen furnace vessel with an inner diameter of ⁇ 1200 mm, and the vacuum is evacuated to a vacuum of 10 Pa or less, and then a hydrogen gas having a purity of 99.999% is introduced to a pressure of 0.12 MPa.
  • the mixture was rotated at a rotation speed of 2 rpm for 6 hours to absorb hydrogen, and then vacuum-dehydrogenated at a temperature of 600 ° C for 3 hours, and then cooled while rotating the vessel at a rotation speed of 10 rpm, and the cooled coarse powder was taken out.
  • Fine pulverization process The coarse powder was finely pulverized using a jet mill to obtain a fine powder having an average particle diameter of 2 ⁇ m.
  • the fine powder after the air flow pulverization is divided into two equal parts.
  • Fine powder heat treatment process 1 part of fine powder is placed in a ⁇ 1200mm stainless steel container, the container is evacuated to a vacuum of 1 Pa or less, and then Ar gas having a purity of 99.9999% is introduced into the container to a pressure of 1000 Pa to control the oxygen content. It is 800 to 1000 ppm, the dew point is -50 ° C to -40 ° C, and the container is placed in an external heat type furnace for heating at a heating temperature of 600 ° C for 2 hours. The container was rotated at a rotation speed of 5 rpm while being heated.
  • the container After heating, the container was taken out from the furnace, and while being externally cooled by water, it was rotated at a rotation speed of 5 rpm, and cooled for 5 hours.
  • Forming process in a magnetic field The powder after heat treatment of the fine powder is not added with an organic additive, and a magnetic field forming machine of a right angle orientation type is directly used, and in a 1.8T orientation magnetic field, it is formed into a side at a molding pressure of 1.2 ton/cm 2 .
  • the cube having a length of 40 mm is demagnetized in a magnetic field of 0.2 T after one molding, and the molded body after the primary molding is sealed as far as possible without coming into contact with air, and is transported to a sintering furnace.
  • 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 other fine powder was not subjected to heat treatment, and as a comparative example, the above-described magnetic field forming process, sintering process, and heat treatment process were sequentially performed in accordance with the same manufacturing conditions except for the fine powder heat treatment.
  • 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, and the average value was evaluated.
  • Oxygen content evaluation process in the sintered body The oxygen content in the sintered body was measured using an EMGA-620W type oxygen-nitrogen analyzer of HORIBA, Japan.
  • the serial number 1-11 is a sintered magnet made of a fine powder which has not been heat-treated
  • the serial number 12-22 is a sintered magnet made of a heat-treated fine powder.
  • the fine powder heat treatment step is added before the forming step in the magnetic field after the air flow grinding and pulverizing step, so that the sinterability of the powder is drastically changed.
  • the purpose of producing a magnet with high coercivity, high squareness, and high heat resistance is achieved.
  • the invention can be applied in industrial production and has good industrial applicability.

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Abstract

本发明公开了基于热处理的稀土磁铁用合金粉末的制造方法和稀土磁铁的制造方法，是将稀土磁铁用合金粗粉碎后再通过气流磨微粉碎制成细粉，所述细粉在真空或惰性气体气氛中以100℃～1000℃的温度进行6分钟以上24小时以下的热处理获得。其是在气流磨微粉碎工序之后，磁场中成形工序之前，增加细粉热处理工序，以使粉末的烧结性发生剧变，达到制成高矫顽力、高方形度、高耐热性的磁铁的目的。

Description

[根据细则37.2由ISA制定的发明名称]　基于热处理的稀土磁铁用合金粉末和稀土磁铁的制造方法 技术领域
本发明涉及磁铁的制造技术领域，特别是涉及一种基于热处理的稀土磁铁用合金粉末的制造方法和稀土磁铁的制造方法。
背景技术
稀土磁铁是以金属间化合物R2T14B主相为基础的磁铁，这其中，R是稀土元素，T是铁，或者是取代铁和铁的一部分的过渡金属元素，B是硼，其拥有极高的磁性能，被人们称为磁王，其最大磁能积（BH）max是铁氧体磁铁（Ferrite）最大磁能积10倍以上，另外，稀土磁铁的工作温度最高可达200摄氏度，机械加工性能极佳，而且其质地坚硬，性能稳定，有很好的性价比，应用极其广泛。
稀土磁铁的制作工艺有以下二种：一种是烧结稀土磁铁，另一种是粘结稀土磁铁。这其中，又以烧结稀土磁铁的应用最为广泛。现有技术中，烧结稀土磁铁的制作工艺主要包括如下流程：原料配制→熔炼→铸造→氢破粉碎（HD）→气流粉碎（JM）→磁场成形→烧结→热处理→磁性能评价→烧结体中的氧含量评价→加工→表面处理等。
用一句话来概括稀土烧结磁铁的发展史的话，可以说成是提高主相含有率，降低稀土组成的开发过程也不为过。目前，为提高(BH)max、矫顽力，制造方法整体的防氧化技术不断发展，目前烧结磁铁中的氧含量可降至2500ppm以下，但是，烧结中氧含量较低的话，微量成分波动、工序中杂质的混入等不稳定因素的影响也会扩大，这就容易引起过烧结现象和晶粒异常长大（AGG），也会产生矫顽力、方形度、耐热性低下等问题。
发明内容
本发明的目的之一在于克服现有技术之不足，提供一种基于热处理的稀土磁铁用合金粉末的制造方法，其是在气流磨微粉碎工序之后，磁场中成形工序之前，增加细粉热处理工序，以使粉末的烧结性发生剧变，达到制成高矫顽力、高方形度、高耐热性的磁铁的目的。
本发明解决其技术问题所采用的技术方案是：
基于热处理的稀土磁铁用合金粉末的制造方法，所述的稀土磁铁为含有R2T14B主相的磁铁，所述的R为选自包含钇元素在内的稀土元素中的至少一种，所述T为包括Fe的至少一种过渡金属元素，其特征在于，包括如下的步骤：将稀土磁铁用合金粗粉碎后再通过气流磨微粉碎制成细粉，所述细粉在真空或惰性气体气氛中以100℃～1000℃的温度进行6分钟以上24小时以下的热处理获得。
增加细粉热处理工序之所以能够达到如上的效果，这是因为，通过细粉热处理，产生如下的现象：
1）全部的合金粉末表面在真空或惰性气体气氛中不可避的氧化气体作用下均产生了极少量的氧化层，粉末在后续工艺中的氧化活性变弱；
2）合金粉末的锐利边角熔解变圆，减少粉末之间的接触面，可使粉末间的润滑性变好，修复粉末表面晶格缺陷，提高粉末取向度及磁铁矫顽力；
3）通过韧化效果去除粉末表面附近的划痕，可避免因缺陷等造成的烧结促进效果的损失。
上述多种因素综合作用，使粉末的性能发生剧变，达到制成高矫顽力、高方形度、高耐热性的磁铁的目的。
在推荐的实施方式中，所述细粉热处理工序的温度优选为300℃～700℃。
在推荐的实施方式中，所述细粉热处理工序中，对所述细粉进行振动或摇动。细粉热处理工序中，为防止粉末间的附着及凝结，最好是使用旋转炉之类的炉进行处理，可提高生产效率。
在推荐的实施方式中，所述真空状态热处理工序中，压力在10-2Pa～500Pa ，氧含量为0.5ppm～2000ppm，露点为-60℃～20℃。本发明经过大量的试验，控制气氛中氧化气体（包括水和氧气）含量，使全部合金粉末的表面均能产生且仅能产生极少量的氧化层，使得经过上述条件热处理的细粉具有极佳的润滑性，并在后续烧结和重稀土扩散工序中发挥抗氧化性能，以制成高矫顽力、高方形度、高耐热性的磁铁。另外，由于将真空的压力设在500Pa以下，远小于标准大气压的压力，根据平均自由程的公式，氧化气体的平均自由程与压力P成反比，因此，氧化气体与合金粉末发生反应的概率更为均匀，使位于表层、中层和底层的粉末均得以发生氧化反应，从而获得高性能粉末。
在推荐的实施方式中，所述惰性气体气氛热处理工序中，压力在10-1Pa～1000Pa ，氧含量为0.5ppm～2000ppm，露点为-60℃～20℃。效果同上段。
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。
在推荐的实施方式中，所述粗粉碎的步骤是将稀土磁铁用合金在0.01MPa以上、1MPa以下的氢气压力下保持0.5～6小时进行氢破粉碎，之后抽真空脱氢的步骤。
在推荐的实施方式中，所述稀土磁铁用合金以原子百分比计，其成分为Re Tf Ag Jh Gi Dk ，其中：
R为Nd或包含Nd和选自La、Ce、Pr、Sm、Gd、Dy、Tb、Ho、Er、Eu、Tm、Lu或Y中的至少一种，T为Fe或包含Fe和选自Ru、Co或Ni中的至少一种，A为B或包含B和选自C或P中的至少一种，J为选自Cu、Mn、Si或Cr中的至少一种，G为选自Al、Ga、Ag、Bi或Sn中的至少一种，D为选自Zr、Hf、V、Mo、W、Ti或Nb中的至少一种；以及
e的原子百分比at%为12≤e≤16，
g的原子百分比at%为5≤g≤9，
h的原子百分比at%为0.05≤h≤1，
i的原子百分比at%为0.2≤i≤2.0，
k的原子百分比at%为0≤j≤4，
f的原子百分比at%为f＝100-e-g-h-i-k。
需要说明的是，O、N作为操作过程中容易混入的杂质，合金粉末中可能会存在O、N以常规杂质含量的少量混入。
本发明的另一目的在于提供一种稀土磁铁的制造方法。
稀土磁铁的制造方法，所述的稀土磁铁为含有R2T14B 主相的磁铁，所述的R为选自包含钇元素在内的稀土元素中的至少一种，所述T为包括Fe的至少一种过渡金属元素，其特征在于，包括如下的步骤：将稀土磁铁用合金粗粉碎后再通过气流磨微粉碎制成细粉，所述细粉在真空中或惰性气体气氛中以100℃～1000℃的温度进行6分钟以上24小时以下的热处理，之后使用磁场成形法进行成形，在真空或惰性气体中以950℃～1140℃的温度进行烧结。
与现有技术相比，本发明具有如下的特点：
1）将微粉碎后的细粉以100℃～1000℃的温度进行6分钟以上24小时以下的热处理，通过细粉热处理，可使粉末的性能发生剧变，达到制成高矫顽力、高方形度、高耐热性的磁铁的目的；
2）与以往相比，粉末能在比常规方法高20～40℃的高温下进行烧结，并且不会发生晶粒异常长大（AGG），热处理后的粉末能在特别广泛的烧结温度范围都可进行烧结，拓展了生产条件。
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1
原料配制过程：准备纯度99.5%的Nd、Pr、Dy、Tb和Gd，工业用Fe-B，工业用纯Fe，纯度99.99%的Co，纯度99.5%的Cu、Mn、Al、Ag、Mo和C。以原子百分比at%计，按照成分为Re Tf Ag Jh Gi Dk 来配制。
各元素的含量如下表1所示：
表 1 各元素的配比
R T A J G D
Nd Pr Dy Tb Gd Fe Co C B Cu Mn Al Ag Mo
7 3 1 1 1 余量 1 0.05 7 0.2 0.2 0.2 0.1 1
按照上述配制组成，合计称量、配制了500Kg的原料。
熔炼过程：取500Kg配制好的原料放入氧化铝制的坩埚中，在高频真空感应熔炼炉中在1Pa的真空中以1650℃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8万Pa后，使用甩带铸造法（SC）铸造成平均厚度为0.3mm的铸片。
氢破粉碎（即粗粉碎）过程：将平均厚度为0.3mm的铸片放入内径为ϕ1200mm的不锈钢制旋转式氢破炉容器中，容器抽真空使真空度达到10Pa以下，之后通入纯度为99.999%的氢气至压力为0.12MPa，容器按1rpm的旋转速度旋转2小时吸氢破碎，之后，在600℃的温度下抽2小时真空脱氢，而后按30rpm的旋转速度一边旋转容器一边冷却，取出冷却后的粗粉。
微粉碎过程：使用气流微粉碎机对粗粉进行微粉碎，获得平均粒径为4.2μm的细粉。
细粉热处理过程：将细粉分成均等的8份，每份细粉分别放入ϕ1200mm的不锈钢制容器中，将容器分别抽真空使压力达到10-1Pa，氧含量为1～100ppm，露点为0～10℃，之后将不锈钢制容器放入外热式炉中进行加热。
每份细粉加热温度、时间如表2所示，加热时不锈钢制容器以10rpm的旋转速度进行旋转。
加热后，将容器从外热式炉中取出，一边在外部进行水冷一边按20rpm的旋转速度进行旋转，冷却3小时。
磁场中成形过程：热处理后的细粉粉末中不添加成形助剂及润滑剂等有机物，使用直角取向型的磁场成型机，在2.1T的取向磁场中，在0.2ton/cm2的成型压力下，一次成形为边长为40mm的立方体，一次成形后在0.2T的磁场中退磁。
为使一次成形后的成形体尽可能地不接触到空气将其进行密封，使用二次成形机（等静压成形机）在1.2ton/cm2 的压力下进行二次成形。
烧结过程：将各成形体送至烧结炉进行烧结，烧结在10-3 Pa的真空下，在200℃和600℃的温度下各保持2小时后，在0.01MPa的Ar气体气氛中以1080℃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。
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。
烧结体中的氧含量评价过程：烧结体中的氧含量使用日本HORIBA公司的EMGA-620W型氧氮分析仪进行检测。
表 2 不同加热温度、时间的细粉热处理后的磁性能评价和氧含量评价的情况
序号 热处理温度(℃) 热处理时间（hr） Br(kGs) Hcj（k0e） SQ(%) (BH)max(MG0e) 烧结体氧含量（ppm）
0 比较例 无细粉热处理 10.1 11.4 82 21.4 2580
1 比较例 80 30 10.2 11.6 82.3 22.8 1589
2 本发明 100 24 12 35.1 98.2 31.2 562
3 本发明 300 6 12.3 35.4 99.1 35.3 375
4 本发明 500 4 12.3 36.7 99.1 35.2 369
5 本发明 700 1 12.3 37.8 99.2 35.2 383
6 本发明 1000 0.3 11.8 34.5 98.5 33.2 582
7 比较例 1020 0.5 10.6 27.6 84.2 23.2 1587
8 比较例 1050 12 10.2 24.3 78.6 16.5 2598
从表2可以看出，通过细粉热处理，均匀地在全部粉末表面形成非常薄的氧化膜，可使粉末间的润滑性变好，提高粉末的取向度，这样就可获得较高的Br、（BH）max，且烧结时不易引起晶粒异常长大，可形成较细的组织，矫顽力Hcj激增；另外，通过细粉热处理，粉末表面的锐利部被熔解，形状变圆，局部的反磁场系数变高，这样也可获得较高的矫顽力。且，在成形至烧结的工序，表面形成均匀氧化膜的细粉活性变弱，在成形至烧结的工序，就算接触到大气，也不会发生激烈的氧化，而没有经过热处理的细粉则活性较强容易氧化，在成形至烧结的工序，就算只接触到一点点的大气，也会发生激烈的氧化，导致烧结体的氧含量变高。
需要说明的是，在细粉的热处理温度超过1000℃时，细粉粒子表面生成的氧化膜容易扩散到粒子内，结果就会同无氧化膜一样，粉末间的附着力变高，这样的话，Br、（BH）max会变得极差，且烧结时就容易产生晶粒异常长大（AGG），使矫顽力Hcj降低。
以往，在低氧含量工序中，由于磁铁粉末间的粘着力很强，存在磁铁粉末取向度不高的问题，这样也会存在磁铁Br、（BH）max低下的问题，且由于磁铁粉末间表面活性度很高，烧结时晶粒和晶粒容易融着，就会产生晶粒异常长大（AGG），使矫顽力急降，在使用了本发明的方法之后，上述问题同样得以解决。
实施例2
原料配制过程：准备纯度99.9%的Nd、Y，工业用Fe-B，工业用Fe-P，工业用Fe-Cr，工业用纯Fe、纯度99.9%的Ni、Si，纯度99.5%的Sn、W。
以原子百分比at%计，按照成分为Re Tf Ag Jh Gi Dk 来配制。
各元素的含量如表3所示：
表 3 各元素的配比
R T A J G D
Nd Y Fe Ni B P Cr Si Sn W
12.7 0.1 余量 0.1 5.9 0.05 0.2 0.1 0.3 0.01
按照上述配制组成，合计称量、配制了500Kg的原料。
熔炼过程：取500Kg配制好的原料放入氧化铝制的坩埚中，在高频真空感应熔炼炉中在10-2 Pa的真空中以1600℃以下的温度进行真空熔炼。
铸造过程：真空熔炼后的熔炼炉中通入Ar气体使气压达到5万Pa后，在水冷圆盘状铸造板中铸造成平均厚度为2mm的铸片。
氢破粉碎过程：将铸片放入内径为ϕ1200mm的不锈钢制旋转式氢破炉容器中，容器抽真空使真空度达到10Pa以下，之后通入纯度为99.999%的氢气至压力0.12MPa，不锈钢制旋转式氢破炉容器按1rpm的旋转速度旋转2小时吸氢破碎，之后在600℃的温度下抽2小时真空脱氢，而后按30rpm的旋转速度一边旋转容器一边冷却，取出冷却后的粗粉。
微粉碎过程：使用气流微粉碎机对粗粉进行微粉碎，获得平均粒径为6.8μm的细粉，分成6等份。
细粉热处理过程：4份气流粉碎后的细粉分别放入ϕ1200mm的不锈钢制容器中，将容器分别抽真空使真空度达到10-2 Pa，氧含量为0.5～50ppm，露点为10～20℃，之后将容器放入外热式炉中进行加热；加热温度为600℃，时间为2小时，加热时容器以1rpm的旋转速度进行旋转。
加热后，将容器从外热式炉中取出，一边在外部进行水冷一边按20rpm的旋转速度进行旋转，冷却3小时。
磁场中成形过程：4份细粉热处理后的粉末和剩余2份不经过细粉热处理的粉末中均不添加有机添加剂，并各自使用直角取向型的磁场成型机，在2T的取向磁场中，在0.20ton/cm2 的成型压力下，一次成形为边长40mm的立方体；一次成形后在0.2T的磁场中退磁；为使一次成形后的成形体尽可能地不接触到空气将其进行密封，使用二次成形机（等静压成形机）在1.2ton/cm2 的压力下进行二次成形。
烧结过程：将各成形体送至烧结炉进行烧结，烧结在10-3 Pa的真空下，在300℃和500℃的温度下各保持2小时后，以1050℃的温度烧结6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：将2份未经过热处理的粉末制成的烧结体加工成ϕ15mm、厚度5mm的磁铁，5mm方向为磁场取向方向，其中1份烧结体制成的磁铁作为无晶界扩散处理的磁铁直接进行磁性能检测，评定其磁特性（比较例1），另1份烧结体制成的磁铁洗净，表面洁净化后，按表4中A中方法进行晶界扩散处理（比较例2）。
将4份经过热处理的粉末制成的烧结体加工成ϕ15mm、厚度5mm的磁铁，5mm方向为磁场取向方向，其中1份烧结体制成的磁铁作为无晶界扩散处理的磁铁直接进行磁性能检测，评定其磁特性（比较例3）。
在晶界扩散处理过程：将另外3份由经过热处理的粉末制成的烧结体加工后的磁铁洗净，表面洁净化后，每份烧结体制成的磁铁分别按表4中A、B、C三种方法进行晶界扩散处理。
表 4 晶界扩散处理方法
　 晶界扩散的种类 工序明细
A Dy 氧化物粉末、 Tb 氟化物粉末的涂覆扩散法 使用 Dy 氧化物和 Tb 氟化物按 3:1 比例配制成的原料，全面喷雾涂覆在磁铁上，将涂覆后的磁铁干燥，在高纯度 Ar 气体气氛中，以 850 ℃ 的温度扩散热处理 12 小时。
B （ Dy 、 Tb)-Ni-Co-Al 系合金细粉涂覆扩散法 将 Dy30Tb30Ni5Co25Al 10 合金微粉碎为平均结晶粒为 15μm 的细粉，全面喷雾涂覆在磁石上，将涂布后的磁铁干燥，在高纯度 Ar 气体气氛中，以 950 ℃ 的温度扩散热处理 12 小时。
C Dy 金属蒸汽扩散法 在真空热处理炉中，将 Dy 金属板、 Mo 网和磁铁一起放入，以 1010 ℃ 的温度在 Ar 气氛中蒸汽处理 6 小时。
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。
烧结体中的氧含量评价过程：烧结体中的氧含量使用日本HORIBA公司的EMGA-620W型氧氮分析仪进行检测。
表5是在细粉热处理和晶界扩散处理情况下实施例和比较例的磁性能评价和氧含量评价的情况。
表 5 实施例和比较例的磁性能评价和氧含量评价的情况
序号 　 细粉热处理 晶界扩散 Br(kGs) Hcj （ k0e ） SQ(%) (BH)max(MG0e) 烧结体氧含量（ ppm ）
0 比较例 1 无 无 13.1 6.5 76.5 23.1 2687
1 比较例 2 无 A 13.2 13.2 86.6 32.5 2785
2 比较例 3 有 无 15.4 9.5 86.7 46.4 421
3 本发明 有 A 15.5 22.3 98.4 56.5 278
4 本发明 有 B 15.6 22.4 99.2 56.8 276
5 本发明 有 C 15.6 24.2 99.1 57.2 289
从表5可以看出，由经过热处理的细粉烧结制得的磁铁晶界处氧的存在状态发生明显变化，Dy、Tb等的扩散速度变快，扩散效率高，可以在较短的时间内完成晶界扩散，晶界扩散的效果非常明显，矫顽力显著提高。
实施例3
原料配制过程：准备纯度99.5%的La、Ce、Nd、Tb、Ho，工业用Fe-B，工业用纯Fe，纯度99.99%的Ru，纯度99.5%的P、Si、Cr、Ga、Sn、Zr；以原子百分比at%计，按照成分为Re Tf Ag Jh Gi Dk 来配制。
各元素的含量如下所示：
R成分中，La为0.1，Ce为0.1，Nd为12，Tb为0.2，Ho为0.2；
T成分中，Fe 为余量，Ru为1；
A成分中，P为0.05，B为7；
J成分中，Si为0.2，Cr为0.2；
G成分中，Ga为0.2，Sn为0.1；
D成分中，Zr为0.5。
按照上述配制组成，合计称量、配制了500Kg的原料。
熔炼过程：取500Kg配制好的原料放入氧化铝制的坩埚中，在高频真空感应熔炼炉中在1Pa的真空中以1650℃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8万Pa后，使用甩带铸造法（SC）铸造成平均厚度为0.15mm的铸片。
氢破粉碎过程：将铸片放入内径为ϕ1200mm的不锈钢制旋转式氢破炉容器中，容器抽真空使真空度达到10Pa以下，之后通入纯度为99.999%的氢气至压力为0.12MPa，容器按1rpm的旋转速度旋转2小时吸氢破碎，之后，在600℃的温度下抽2小时真空脱氢，而后按30rpm的旋转速度一边旋转容器一边冷却，取出冷却后的粗粉。
微粉碎过程：使用气流微粉碎机对粗粉进行微粉碎，获得平均粒径为5μm的细粉；
细粉热处理过程：气流粉碎后的细粉分成6等份，每份分别放入ϕ1200mm的不锈钢制容器中，将容器分别抽真空使达到10Pa以下的真空，之后通入纯度为99.9999%的Ar气至压力为500Pa，控制氧含量为1800～2000ppm，露点为-60℃～-50℃，再将容器放入外热型炉中进行加热，加热时容器以5rpm的旋转速度进行旋转。
每份加热温度、时间如表6中所示。
加热后，将容器从外热式炉中取出，一边在外部进行水冷一边按20rpm的旋转速度进行旋转，冷却3小时。
磁场中成形过程：细粉热处理后的粉末中不添加有机添加剂，直接使用直角取向型的磁场成型机，在1.8T的取向磁场中，在1.2ton/cm2 的成型压力下，一次成形为多个边长40mm的立方体，一次成形后在0.2T的磁场中退磁，为使一次成形后的成形体尽可能地不接触到空气将其进行密封，运至烧结炉。
烧结过程：将各成形体送至烧结炉进行烧结，烧结在10-3 Pa的真空下，在200℃和600℃的温度下各保持2小时后，在0.02MPa的Ar气体气氛中以1080℃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。
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，评价平均值。
烧结体中的氧含量评价过程：烧结体中的氧含量使用日本HORIBA公司的EMGA-620W型氧氮分析仪进行检测。
相同加热温度、不同时间的细粉热处理后的实施例和比较例的磁性能评价和氧含量评价的情况如表6中所示。
表 6 实施例和比较例的磁性能评价和氧含量评价的情况
序号 热处理温度(℃) 热处理时间(hr) Br （ kGs) Hcj （ k0e ） SQ(%) (BH)max(MG0e) 烧结体中氧含量（ ppm ）
0 比较例 700 0.05 13.8 9.8 81.2 45.3 2980
1 本发明 700 0.1 15.1 13.3 97.8 54.3 565
2 本发明 700 1 15.2 13.6 98.2 54.8 354
3 本发明 700 4 15.3 14.2 99.1 55.2 375
4 本发明 700 12 15.4 14.1 99.2 56 395
5 本发明 700 24 15.3 13.5 99.1 55.3 573
6 比较例 700 48 14.9 11.7 94.8 52.7 980
从表6可以看出，在700℃的温度下，细粉的热处理时间不满0.1小时之时，细粉热处理的效果不充分，这样就会和同没有氧化膜时一样，粉末间的附着力变高，这样的话，Br、（BH）max会变得极差。另外，也容易产生AGG，使矫顽力降低。
同时，在700℃的温度下，细粉热处理时间超过24小时之时，细粉粒子表面生成的氧化膜被吸收扩散到粒子内，结果就会同无氧化膜一样，会使氧含量增加，Br、（BH）max降低，极易产生AGG，使矫顽力Hcj降低。
实施例4
原料配制过程：准备纯度99.5%的Lu、Er、Nd、Tm、Y，工业用Fe-B，工业用纯Fe，纯度99.99%的Co，纯度99.5%的C、Cu、Mn、Ga、Bi、Ti，以原子百分比at%计，按照成分为Re Tf Ag Jh Gi Dk 来配制。
各元素的含量如下如：
R成分中，Lu为0.2，Er为0.2，Nd为12，Tm为0.5，Y为0.6；
T成分中，Fe 为余量，Co为1；
A成分中，C为0.05，B为7；
J成分中，Cu为0.2，Mn为0.2；
G成分中，Ga为0.2，Bi为0.1；
D成分中，Ti为4。
按照上述配制组成，合计称量、配制了500Kg的原料。
熔炼过程：取500Kg配制好的原料放入氧化铝制的坩埚中，在高频真空感应熔炼炉中在0.1Pa的真空中以1550℃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4万Pa后，使用甩带铸造法（SC）铸造成平均厚度为0.6mm的铸片。
氢破粉碎过程：将铸片放入内径为ϕ1200mm的不锈钢制旋转式氢破炉容器中，容器抽真空使真空度达到10Pa以下，之后通入纯度为99.999%的氢气至压力为0.12MPa，容器按2rpm的旋转速度旋转6小时吸氢破碎，之后在600℃的温度下抽3小时真空脱氢，而后按10rpm的旋转速度一边旋转容器一边冷却，取出冷却后的粗粉。
微粉碎过程：使用气流微粉碎机对粗粉进行微粉碎，获得平均粒径为2μm的细粉。
气流粉碎后的细粉分成2等份。
细粉热处理过程：1份细粉放入ϕ1200mm的不锈钢制容器中，容器抽真空使达到1Pa以下的真空，之后往该容器中通入纯度为99.9999%的Ar气至压力为1000Pa，控制氧含量为800～1000ppm，露点为-50℃～-40℃，将容器放入外热型炉中进行加热，加热温度为600℃，时间为2小时。加热时容器以5rpm的旋转速度进行旋转。
加热后，将容器从炉中取出，一边在外部进行水冷一边按5rpm的旋转速度进行旋转，冷却5小时。
磁场中成形过程：细粉热处理后的粉末中不添加有机添加剂，直接使用直角取向型的磁场成型机，在1.8T的取向磁场中，在1.2ton/cm2 的成型压力下，一次成形为边长40mm的立方体，一次成形后在0.2T的磁场中退磁，为使一次成形后的成形体尽可能地不接触到空气将其进行密封，运至烧结炉。
烧结过程：将各成形体搬至烧结炉进行烧结，烧结在10-3 Pa的真空下，在200℃和600℃的温度下各保持2小时后，在0.02MPa的Ar气体气氛中分别以925℃～1150℃的温度烧结，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。
另1份细粉不进行热处理，作为比较例，按照除细粉热处理以外的相同制造条件依次进行上述磁场成形过程、烧结过程和热处理过程。
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，评价平均值。
烧结体中的氧含量评价过程：烧结体中的氧含量使用日本HORIBA公司的EMGA-620W型氧氮分析仪进行检测。
有或无细粉热处理后在不同烧结温度情况下的实施例和比较例的磁性能评价和氧含量评价的情况如表7中所示。其中，序号1-11为未经热处理的细粉制成的烧结磁铁，序号12-22为经热处理的细粉制成的烧结磁铁。
表 7 实施例和比较例的磁性能评价和氧含量评价的情况
序号 　 热处理 烧结温度（℃） 密度（ g/cc) Br (kGs ) Hcj ( k0e) SQ(%) (BH)max(MG0e) 烧结体氧含量(ppm )
1 比较例 无 925 6.98 12.8 12.8 76.5 25.6 2840
2 比较例 无 950 7.21 13.4 12.3 93.2 39.8 2940
3 比较例 无 975 7.32 13.6 12.1 95.6 43.2 2850
4 比较例 无 1000 7.38 13.9 11.9 96.3 44.5 2840
5 比较例 无 1025 7.53 14.1 11.5 96.4 44.7 2840
6 比较例 无 1050 7.54 14.2 11.2 96.3 45.9 2870
7 比较例 无 1075 7.56 14.2 10.9 96.4 47.1 2780
8 比较例 无 1100 7.57 14.3 10.2 96.2 47.2 2790
9 比较例 无 1125 7.55 14.1 9.2 92.3 46.7 2830
10 比较例 无 1140 7.51 13.8 8.5 87.4 39.8 2840
11 比较例 无 1150 7.48 13.6 7.6 82.3 37.6 2980
12 比较例 有 925 7.23 13.8 9.8 81.2 45.3 982
13 本发明 有 950 7.47 14.4 13.8 97.8 50.1 354
14 本发明 有 975 7.49 14.4 13.6 98.2 50.2 341
15 本发明 有 1000 7.51 14.5 13.5 98.3 50.4 340
16 本发明 有 1025 7.54 14.5 13.4 98.4 50.4 342
17 本发明 有 1050 7.56 14.6 13.4 98.5 50.6 345
18 本发明 有 1075 7.59 14.6 13.4 98.6 50.8 343
19 本发明 有 1100 7.61 14.7 13.4 98.9 50.8 346
20 本发明 有 1125 7.64 14.7 13.4 99 51.1 347
21 本发明 有 1140 7.65 14.8 13.4 99.1 51.2 349
22 比较例 有 1150 7.32 13.4 12.2 76.5 38.4 768
从表7可以看出，通过细粉热处理，可以扩宽获得高性能的烧结温度范围。这是因为，防止了氧化就可以在低烧结温度下进行烧结，另一方面，在高温烧结时，同样不会发生晶粒异常长大（AGG），这样一来，不管是低温烧结还是高温烧结都能获得很好的结果。
上述实施例仅用来进一步说明本发明的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
本发明基于热处理的稀土磁铁用合金粉末的制造方法和稀土磁铁的制造方法，是在气流磨微粉碎工序之后，磁场中成形工序之前，增加细粉热处理工序，以使粉末的烧结性发生剧变，达到制成高矫顽力、高方形度、高耐热性的磁铁的目的。本发明可以在工业生产上应用，具有良好的工业实用性。

Claims (11)

  1. 基于热处理的稀土磁铁用合金粉末的制造方法，所述的稀土磁铁为含有R2T14B 主相的磁铁，所述的R为选自包含钇元素在内的稀土元素中的至少一种，所述T为包括Fe的至少一种过渡金属元素，其特征在于，包括如下的步骤：将稀土磁铁用合金粗粉碎后再通过气流磨微粉碎制成细粉，所述细粉在真空或惰性气体气氛中以100℃～1000℃的温度进行6分钟以上24小时以下的热处理。
  2. 根据权利要求1所述的基于热处理的稀土磁铁用合金粉末的制造方法，其特征在于：所述细粉热处理的温度为300℃～700℃。
  3. 根据权利要求2所述的基于热处理的稀土磁铁用合金粉末的制造方法，其特征在于：所述细粉热处理工序中，对所述细粉进行振动或摇动。
  4. 根据权利要求1或2或3所述的基于热处理的稀土磁铁用合金粉末的制造方法，其特征在于：所述真空状态热处理工序中，压力在10-2 Pa～500Pa ，氧含量为0.5ppm～2000ppm，露点为-60℃～20℃。
  5. 根据权利要求1或2或3所述的基于热处理的稀土磁铁用合金粉末的制造方法，其特征在于：所述惰性气体气氛热处理工序中，压力在10-1 Pa～1000Pa ，氧含量为0.5ppm～2000ppm，露点为-60℃～20℃。
  6. 根据权利要求3所述的基于热处理的稀土磁铁用合金粉末的制造方法，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。
  7. 根据权利要求1或2或3所述的基于热处理的稀土磁铁用合金粉末的制造方法，其特征在于：所述粗粉碎过程是将稀土磁铁用合金在0.01MPa以上、1MPa以下的氢气压力下保持0.5～6小时进行氢破粉碎，之后抽真空脱氢的过程。
  8. 根据权利要求3所述的基于热处理的稀土磁铁用合金粉末的制造方法，其特征在于：所述稀土磁铁用合金以原子百分比计，其成分为Re Tf Ag Jh Gi Dk ，其中，R为Nd或包含Nd和选自La、Ce、Pr、Sm、Gd、Dy、Tb、Ho、Er、Eu、Tm、Lu或Y中的至少一种，T为Fe或包含Fe和选自Ru、Co或Ni中的至少一种，A为B或包含B和选自C或P中的至少一种，J为选自Cu、Mn、Si或Cr中的至少一种，G为选自Al、Ga、Ag、Bi或Sn中的至少一种，D为选自Zr、Hf、V、Mo、W、Ti或Nb中的至少一种；以及
    e的原子百分比at%为12≤e≤16，
    g的原子百分比at%为5≤g≤9，
    h的原子百分比at%为0.05≤h≤1，
    i的原子百分比at%为0.2≤i≤2.0，
    k的原子百分比at%为0≤j≤4，
    f的原子百分比at%为f＝100-e-g-h-i-k。
  9. 稀土磁铁的制造方法，所述的稀土磁铁为含有R2T14B 主相的磁铁，所述的R为选自包含钇元素在内的稀土元素中的至少一种，所述T为包括Fe的至少一种过渡金属元素，其特征在于，包括如下的步骤：将稀土磁铁用合金粗粉碎后再通过气流磨微粉碎制成细粉，所述细粉在真空中或惰性气体气氛中以100℃～1000℃的温度进行6分钟以上24小时以下的热处理，之后使用磁场成形法进行成形，在真空或惰性气体中以950℃～1140℃的温度进行烧结。
  10. 根据权利要求9所述的稀土磁铁的制造方法，其特征在于：所述细粉热处理的温度为300℃～700℃。
  11. 根据权利要求10所述的稀土磁铁的制造方法，其特征在于：所述细粉热处理工序中，对所述细粉进行振动或摇动。
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