CN105957675A - Preparation method of rare-earth permanent magnet material - Google Patents

Preparation method of rare-earth permanent magnet material Download PDF

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CN105957675A
CN105957675A CN201610405246.6A CN201610405246A CN105957675A CN 105957675 A CN105957675 A CN 105957675A CN 201610405246 A CN201610405246 A CN 201610405246A CN 105957675 A CN105957675 A CN 105957675A
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magnet
rare earth
mould
powder
preparation
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CN105957675B (en
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郝忠彬
韩相华
章晓峰
洪群峰
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Zhejiang Dongyang Dmegc Rare Earth Co ltd
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Zhejiang Dongyang Dmegc Rare Earth Co ltd
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Priority to PCT/CN2016/089872 priority patent/WO2017210957A1/en
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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
    • 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
    • B22F3/14—Both compacting and sintering simultaneously
    • 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
    • B22F3/24—After-treatment of workpieces or articles
    • 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
    • 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
    • H01F1/0576—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 pressed, e.g. hot working
    • 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
    • H01F1/06—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 in the form of particles, e.g. powder
    • H01F1/08—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 in the form of particles, e.g. powder pressed, sintered, or bound together
    • 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
    • B22F3/14—Both compacting and sintering simultaneously
    • B22F2003/145—Both compacting and sintering simultaneously by warm compacting, below debindering temperature
    • 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
    • B22F3/24—After-treatment of workpieces or articles
    • B22F2003/248—Thermal after-treatment

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Abstract

The invention discloses a preparation method of a rare-earth permanent magnet material. A neodymium-iron-boron magnet is prepared from neodymium-iron-boron alloy powder through continuous two mold pressing processes; an oriented magnetic field needs to be exerted during primary mold pressing to obtain an anisotropic neodymium-iron-boron green body; a compact neodymium-iron-boron magnet is obtained by heating and pressurizing during secondary mold pressing; the size of the magnet is close to that of a final product; and the magnetic property of the magnet is improved through a special heat treatment process. The preparation method of the rare-earth permanent magnet material has the beneficial effects that the densification temperature is low; grain growth can be inhibited; crystalline grains are smaller than a sintered magnet; the magnetic property is high; the size of the magnet is close to that of the final product by the molding pressing processes; and the utilization rate of the material is much higher than that of a traditional sintered neodymium-iron-boron magnet. Special rapidly-quenched magnetic powder is not needed; and thermal deformation is not needed, so that the technology is simple, the production efficiency is high, the production cost is much lower than that of a hot processed/thermally deformed magnet, the magnetic property is high and the maximum magnetic energy product reaches over 200kJm<-3> and is much higher than that of a bonded neodymium-iron-boron magnet.

Description

A kind of preparation method of rare earth permanent-magnetic material
Technical field
The present invention relates to magnetic material correlative technology field, refer in particular to the preparation of a kind of rare earth permanent-magnetic material Method.
Background technology
Since the neodymium iron boron magnetic body appearance eighties in last century, owing to the magnetic property of its excellence is rapidly at electricity The fields such as son, communication, transportation, automatization, medical treatment and new forms of energy obtain and are widely applied.To mesh Till before, Nd-Fe-B permanent magnet material is the permanent magnet material that comprehensive magnetic can be the most excellent, is described as " magnetic king ", To device miniaturization, integrated and high efficiency is significant.
Dividing by preparation method, neodymium iron boron magnetic body is broadly divided into sintering, bonding, hot pressing/heat distortion magnet, its In maximum with sintered NdFeB consumption.The preparation technology of Sintered NdFeB magnet mainly uses strip casting Obtain Nd Fe B alloys, then alloy is ground the powder obtaining 3-5 μm, powder is put in magnetic field and takes Obtain green compact to molding, green compact are obtained sintered NdFeB blank, blank at 1040-1100 DEG C of temperature sintering Sintered NdFeB product is finally given again through machining.The major advantage of sintered magnet is that magnetic property is high, The maximum magnetic energy product of general commercial magnet is typically at 200-400kJm-3, the experiment of NEOMAX company of Japan Room level is up to 474kJm-3, this is also the highest record of magnetic material up to now.And sinter neodymium The major defect of ferrum boron is that stock utilization is low.This is because except small part larger product can be passed through Beyond monolithic molding prepares, other major part sintered NdFeB products are required for machining, compound material Utilization rate is about 66%, and stock utilization is less than 50% for some thin slices and special-shaped product.Separately Outward, the sintering shrinkage of Sintered NdFeB magnet is about 30%, in addition the Density inhomogeneity of green compact, so The strain cracking of sintered NdFeB is inevitable, and Sintered NdFeB magnet improves material use thus The space of rate is the biggest.
The preparation technology of hot pressing/thermal deformation neodymium iron boron magnetic body is that granularity is about the nanocrystalline fast quenching of 200 μm NdFeB magnetic powder obtains isotropic magnet 500-600 DEG C of hot pressing densification, the most again through 850-950 DEG C Lower thermal deformation obtains anisotropic neodymium iron boron magnetic body.In general, the intrinsic coercive of hot pressing/heat distortion magnet Power is more slightly higher than sintered NdFeB, this is because the temperature that hot pressing/thermal deformation uses is lower than sintering temperature, Time is short, so crystal grain is more tiny.And hot pressing/heat distortion magnet can realize dead size or close to net scale Very little molding, can also suppress the strain cracking of magnet, so stock utilization is higher simultaneously effectively.Heat The major defect of pressure/heat distortion magnet is that cost is high.First the nanocrystalline rapidly quenched magnetic powder price used by hot pressing is relatively High；Thermal deformation technique production efficiency is the lowest simultaneously, so production cost is high.
Agglutinate neodymium-iron-boron magnet also uses nanocrystalline rapidly quenched magnetic powder to prepare, a certain proportion of by adding The magnet that magnetic powder is bonded to by bonding agent.The stock utilization of Agglutinate neodymium-iron-boron magnet is the highest, close to 100%, And the preparation of special-shaped product can be realized.The disadvantage of Agglutinate neodymium-iron-boron is that magnetic property is low, and bond neodymium Iron boron magnet magnetic energy product is mostly at 60-90kJm-3。
In sum, the advantage of Sintered NdFeB magnet is that magnetic powder is cheap, and production technology is simple, and efficiency is high, Low cost；Shortcoming is that sintering temperature is high (more than 1040 DEG C), and magnet crystal grain is easily grown up, stock utilization Low, yielding cracking.The advantage of hot pressing/heat distortion magnet is that magnet crystal grain is tiny, and stock utilization is high； Shortcoming is that magnetic powder (the special quenched powder of hot pressing/thermal deformation) price is high, and thermal deformation efficiency is low, and cost is high.Viscous The advantage of knot neodymium iron boron magnetic body is that stock utilization is high, it is possible to achieve the production of abnormity magnet；Major defect Being that magnetic property is low, Agglutinate neodymium-iron-boron magnet magnetic energy product is mostly at 60-90kJm-3。
Summary of the invention
The present invention is to there is above-mentioned deficiency in prior art to overcome, it is provided that a kind of magnetic property is high and raw Produce the preparation method of the rare earth permanent-magnetic material of low cost.
To achieve these goals, the present invention is by the following technical solutions:
The preparation method of a kind of rare earth permanent-magnetic material, comprises the steps:
(1) magnetic powder prepares: use vacuum melting furnace to prepare Nd Fe B alloys, uses the quick-fried method of hydrogen or machine afterwards Tool crush method carries out coarse crushing, then uses airflow milling technique to be ground preparing Nd Fe B alloys Powder；
(2) one-step mould: powder is put into compression molding in the mould of one-step mould, magnetic powder is executed simultaneously Add the magnetic field more than 1T；
(3) secondary mould pressing: the product of one-step mould is inserted in the mould of secondary mould pressing, in vacuum or lazy Property gas shield under, after the product of one-step mould is heated, then apply pressure and carry out secondary Mold, obtain the magnet of densification；
(4) heat treatment: carry out heat treatment in inserting vacuum drying oven through the magnet of secondary mould pressing, at least wrap Include the homogenization heat treatment of passivation crystal grain wedge angle and optimize the tempering heat treatment of Grain-Boundary Phase distribution.
In the present invention, the Nd Fe B alloys powder of employing, prepare neodymium iron boron by double mould pressing process Magnet；Alignment magnetic field need to be applied when one-step mould, obtain anisotropic neodymium iron boron green compact, at secondary Pressurizeed by heating during mold pressing, obtain densification neodymium iron boron magnetic body, and magnet be closely sized to finally produce The size of product；Magnet magnetic property owing to obtaining after secondary mould pressing is the lowest, so needing by special heat Process technique and improve magnet magnetic property.Using mould pressing process, product is close to the size of final finished, material Material utilization rate is high；Without thermal deformation, production efficiency is high, so cost is far below hot pressing/heat distortion magnet； Magnetic property reaches 200kJm-3Above, far above Agglutinate neodymium-iron-boron magnet.
As preferably, in step (1), the Nd Fe B alloys powder used is micron crystalline substance or monocrystalline Grain, grinds the Nd Fe B alloys powder average particle size range prepared and controls in 1-10 μm.The neodymium used Ferrum boron powder is micron crystalline substance, single crystal grain, so using conventional vacuum smelting furnace to prepare, magnetic powder becomes This is low.
As preferably, in step (1), after grinding prepared Nd Fe B alloys powder, add rich dilute Soil alloy powder, the constituent of rich rare earth alloy powder is: in Rare Earth Elements of Praseodymium, neodymium, dysprosium, terbium One or more, other non-rare earths are one or more in aluminum, copper, gallium, ferrum, and rare earth unit Element praseodymium, neodymium, dysprosium, the mass percent sum of terbium are more than 50%；The adding proportion of rich rare earth alloy powder 0-30% for Nd Fe B alloys powder.So can reduce the temperature of secondary mould pressing, contribute to suppression crystalline substance Grain length greatly and extends die life, improves production efficiency simultaneously.
As preferably, described rich rare earth alloy powder average particle size range controls in 0.3-4 μm.Make it Close with the mean diameter of Nd Fe B alloys powder, inhibiting grain growth.
As preferably, in step (3), the mould of secondary mould pressing prepares product needed for final Geomery and design, in step (2), the mould of one-step mould is the mould according to secondary mould pressing And design.So design makes when using mould pressing process, and product is close to the size of final finished, material Material utilization rate is high.
As preferably, in step (3), the product of one-step mould is heated to 550-1000 DEG C, hot pressing Time is 1-30 minute, and the pressure then applying 1-500MPa carries out secondary mould pressing.Due to secondary mould pressing Heating-up temperature far below sintering temperature, so magnet crystal grain is more tiny than conventional sintering magnet, magnetic property is high.
As preferably, in step (4), the homogenizing heat treatment of passivation crystal grain wedge angle is as follows: adopt It is incubated 1-15 hour with 700-1000 DEG C；The tempering heat treatment process optimizing Grain-Boundary Phase distribution is as follows: use 400-650 DEG C is incubated 1-6 hour.Improve magnet magnetic property by above-mentioned special Technology for Heating Processing, make Obtain magnetic property and reach 200kJm-3Above, far above Agglutinate neodymium-iron-boron magnet, this is also that this technique can prepare There is the critical process of commercial value magnet.
As preferably, after step (4), it is further added by destressing and processes technique: use 150-350 DEG C It is incubated 0.5-3 hour.So it is favorably improved magnetic property and the bending strength of magnet.
The invention has the beneficial effects as follows:
1, densification temperature is low, can inhibiting grain growth, crystal grain is tiny compared with sintered magnet, and magnetic property is high； By displaing microstructure observing it is found that the magnet crystallite dimension for preparing of the present invention is tiny, for 1-5 μm, Close with the mean diameter of Nd Fe B alloys powder, do not occur substantially in secondary mould pressing densification process The phenomenon that crystal grain is grown up；
2, using mould pressing process, magnet size is close to the size of final finished, and stock utilization is far above passing System Sintered NdFeB magnet；
3, need not special rapidly quenched magnetic powder, it is not necessary to thermal deformation, technique is simple, and production efficiency is high, produces Cost is far below hot pressing/heat distortion magnet；
4, magnetic property is high, and maximum magnetic energy product reaches 200kJm-3Above, far above Agglutinate neodymium-iron-boron magnet.
Detailed description of the invention
Below in conjunction with detailed description of the invention, the present invention will be further described.
Embodiment 1:
1, use vacuum melting furnace to prepare Nd Fe B alloys, utilize the rapid hardening slice technique by master alloying composition to be The alloy of Nd26.25Pr8.75Fe64B1 (weight/mass percentage composition) is laminated；Then utilize the quick-fried method of hydrogen and Rapid hardening thin slice is made the powder that mean diameter is 3.5 μm by airflow milling technique；
2, applying the magnetic field of 1.5T, one-step mould obtains blank dimension R8.1 × R3.6 × 10, blank weight Amount 29.97g；
3, being placed in the mould of secondary mould pressing by the blank that one-step mould obtains, the mould of secondary mould pressing is in One airtight space, is first evacuated to 8 × 10-3Pa, then applying argon gas is to 8 × 104Pa, then heats to 780 DEG C, pressurize the direction along thickness 10 200MPa, and pressurize cools down after 6 minutes and takes out；
4, in inserting vacuum drying oven through the magnet of secondary mould pressing, carry out secondary heat treatment, be respectively adopted 900 DEG C Being incubated 4 hours technique of insulation in 8 hours and 500 DEG C and hot pressing blank carries out heat treatment, prepared specification is The magnet of R8.1 × R3.6 × 5.3, stock utilization 100%, ftracture without arrisdefect, yield rate 100%.
Embodiment 2:
1, use the magnet in embodiment 1, the Nd Fe B alloys powder prepared after step 1 adds The rich rare earth alloy powder of 5%Nd70Cu30 (weight/mass percentage composition), wherein neodymium copper alloy powder is average Particle diameter is 3 μm；
2, in step 3, hot pressing temperature is 680 DEG C, and other techniques are same as in Example 1.
Embodiment 3:
By the magnet of embodiment 2 after the heat treatment of step 4, carry out 340 DEG C × 2.5 hours go Stress tempering processes.
Comparative example 1:
Using with embodiment 1 with batch magnetic powder oriented moulding, green compact specification 43.56 × 39.6 × 29.82, by passing System sintering process processes at 1068 DEG C of sintering densifications, process heat same as in Example 1.
Sintering blank specification 33 × 30 × 2, line cuts into the black-film of R8.1 × R3.6 × 5.5 and carries out inside and outside Arc mill processing, finally gives the magnet of R8.1 × R3.6 × 5.3, and stock utilization 76%, machining is taken With 0.3 yuan/, the course of processing has arrisdefect, yield rate 98%.
Embodiment 1, embodiment 2, embodiment 3 contrast see with preparation technology and the product attributes of comparative example 1 Table 1.After molding densification in embodiment 2 and embodiment 3, the average grain size of magnet is about 3.6 μ M, close with the granularity of magnetic powder；In embodiment 1, magnet average grain size is 3.8 μm, at high temperature mould In pressure densification process, crystal grain is grown up the least.The average grain size of comparative example 1 magnet is about 5.5 μm, This illustrates that this technology has positive effect to crystal grain refinement.Show that the preparation technology of the employing present invention can be obvious Reduction magnet crystallite dimension, and Grain-Boundary Phase is more evenly distributed.Due to the magnet using this invention to prepare Product design size can meet portions of client without processing and use requirement, so stock utilization is close 100%, the product needed higher for tolerance is simply processed.Use product prepared by this technology Traditional handicraft it is better than, so yield rate has promoted, it might even be possible to reach in terms of machining property 100%.
Table 1
Densification temperature Average grain size Stock utilization Machining is taken Yield rate
Embodiment 1 780℃ 3.8μm ～100% 0 99%
Embodiment 2 680℃ 3.6μm ～100% 0 ～100%
Embodiment 3 680℃ 3.6μm ～100% 0 100%
Comparative example 1 1068℃ 5.5μm 76% 0.3 yuan/only 97%
The neodymium iron boron magnetic body every magnetic property index using different process to prepare is shown in Table 2.Use secondary mould pressing The neodymium iron boron magnetic body magnetic property that technique prepares, particularly Hcj is the lowest, does not reaches the requirement of commercial magnet, Suitable heat treatment must be carried out；At the Technology for Heating Processing of secondary mould pressing magnet and tradition neodymium-iron-boron body heat Science and engineering skill has significantly different, it is necessary first to carries out homogenization heat treatment in order to be passivated crystal grain wedge angle, then enters Row optimizes the tempering heat treatment of grain boundary structure.Had by the magnetic property of magnet after above-mentioned heat treatment and substantially carried Rise, close with Sintered NdFeB magnet, even there is part index number to be better than Sintered NdFeB magnet, be far above Agglutinate neodymium-iron-boron.
In example 2, by adding rich rare earth alloy powder, magnet densification temperature can be reduced, Thus further crystal grain thinning, magnet Hcj also improves.
In embodiment 3, destressing processes and can improve magnet magnetic property, particularly magnet side further Shape degree (Hk/Hcj), is conducive to improving the maximum magnetic energy product of magnet and reducing the irreversible loss of flux of magnet.
Table 2
From above-mentioned Tables 1 and 2, the comparison of embodiment 1, embodiment 2, embodiment 3 and comparative example 1 can Knowing, the present invention can prepare crystal grain rare earth tiny, with low cost forever by hot pressed sintering neodymium iron boron green compact Magnetic material.

Claims (8)

1. a preparation method for rare earth permanent-magnetic material, is characterized in that, comprises the steps:
(1) magnetic powder prepares: use vacuum melting furnace to prepare Nd Fe B alloys, uses the quick-fried method of hydrogen or machinery broken afterwards Broken method carries out coarse crushing, then uses airflow milling technique to be ground preparing Nd Fe B alloys powder；
(2) one-step mould: powder is put into compression molding in the mould of one-step mould, magnetic powder is applied big simultaneously Magnetic field in 1T；
(3) secondary mould pressing: the product of one-step mould is inserted in the mould of secondary mould pressing, at vacuum or indifferent gas Under body protection, after the product of one-step mould is heated, then apply pressure and carry out secondary mould pressing, Magnet to densification；
(4) heat treatment: carry out heat treatment in inserting vacuum drying oven through the magnet of secondary mould pressing, at least include blunt Change the homogenization heat treatment of crystal grain wedge angle and optimize the tempering heat treatment of Grain-Boundary Phase distribution.
The preparation method of a kind of rare earth permanent-magnetic material the most according to claim 1, is characterized in that, in step (1) In, the Nd Fe B alloys powder used is micron crystalline substance or single crystal grain, grinds the Nd Fe B alloys prepared Powder average particle size scope control is in 1-10 μm.
The preparation method of a kind of rare earth permanent-magnetic material the most according to claim 1 and 2, is characterized in that, in step Suddenly, in (1), after grinding prepared Nd Fe B alloys powder, rich rare earth alloy powder, rich rare earth are added The constituent of alloy powder is: one or more in Rare Earth Elements of Praseodymium, neodymium, dysprosium, terbium, other are non- Rare earth element is one or more in aluminum, copper, gallium, ferrum, and Rare Earth Elements of Praseodymium, neodymium, dysprosium, terbium Mass percent sum is more than 50%；The adding proportion of rich rare earth alloy powder is Nd Fe B alloys powder 0-30%.
The preparation method of a kind of rare earth permanent-magnetic material the most according to claim 3, is characterized in that, described richness Rare earth alloy powder average particle size range controls in 0.3-4 μm.
The preparation method of a kind of rare earth permanent-magnetic material the most according to claim 1, is characterized in that, in step (3) In, the mould of secondary mould pressing is to design, in step according to preparing the geomery of product needed for final (2), in, the mould of one-step mould is to design according to the mould of secondary mould pressing.
The preparation method of a kind of rare earth permanent-magnetic material the most according to claim 1, is characterized in that, in step (3) In, the product of one-step mould is heated to 550-1000 DEG C, hot pressing time is 1-30 minute, then applies The pressure of 1-500MPa carries out secondary mould pressing.
The preparation method of a kind of rare earth permanent-magnetic material the most according to claim 1, is characterized in that, in step (4) In, the homogenizing heat treatment of passivation crystal grain wedge angle is as follows: use 700-1000 DEG C to be incubated 1-15 hour； The tempering heat treatment process optimizing Grain-Boundary Phase distribution is as follows: use 400-650 DEG C to be incubated 1-6 hour.
The preparation method of a kind of rare earth permanent-magnetic material the most according to claim 1, is characterized in that, in step (4) Afterwards, it is further added by destressing and processes technique: use 150-350 DEG C to be incubated 0.5-3 hour.
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