CN104752048B

CN104752048B - A kind of preparation method of sintered Nd-Fe-B permanent magnet

Info

Publication number: CN104752048B
Application number: CN201310743639.4A
Authority: CN
Inventors: 何叶青; 惠英林
Original assignee: Beijing Zhong Ke San Huan High Tech Co Ltd
Current assignee: Beijing Zhong Ke San Huan High Tech Co Ltd
Priority date: 2013-12-30
Filing date: 2013-12-30
Publication date: 2017-10-31
Anticipated expiration: 2033-12-30
Also published as: CN104752048A

Abstract

A kind of preparation method of sintered Nd-Fe-B permanent magnet, this method is the dual alloy method using foundry alloy and assistant alloy, it is characterised in that：The crystallite dimension of the assistant alloy is 0.01~0.1 μm.The present invention in for 28~35wt.%, average particle size particle size and crystallite dimension being all 3.0~5.0 μm of the female master alloying powder of sintered NdFeB in common rare earth total content by adding a kind of rare earth total content substantially less than master alloy powder, while method of its crystallite dimension also much smaller than the chilling Nd Fe B alloys adjuvant powders of its particle size, suppress neodymium iron boron pressed compact and the fast growth of crystal grain occurs in sintering process, the generation of big block Nd-rich phase on neodymium iron boron principal phase border is reduced, acquisition manufacturing cost is low, high performance Nd-Fe-B permanent magnet.

Description

A kind of preparation method of sintered Nd-Fe-B permanent magnet

Technical field

The present invention relates to a kind of preparation method of sintered Nd-Fe-B permanent magnet, more particularly to one kind can suppress neodymium iron boron Pressed compact crystal grain fast growth in sintering process, manufacture low cost, the method for high-performance permanent magnet.

Background technology

Two kinds of phases are primarily present as known to those skilled in the art, in Nd Fe B alloys：One is principal phase, and chemical molecular formula is RE₂Fe₁₄B, produces the crucial phase of high permanent magnetism performance, and its volume fraction accounts for more than 95%；Another phase is Nd-rich phase, distribution In RE₂Fe₁₄The border of B main phase grains, plays the magnetostatic coupling between isolation main phase grain and makes magnet with as high as possible HCJ.Therefore, for the excellent permanent magnetism performance of acquisition, it is necessary to will match somebody with somebody as the chemical composition work of Nd Fe B alloys Put：The composition of one side alloy should be as close possible to RE₂Fe₁₄The stoichiometric composition of B principal phases, i.e., be just divided into point；The opposing party There must also be sufficient amount Nd-rich phase in the alloy of face.This means that the total amount of rare earth in the chemical composition of Nd Fe B alloys is necessary More than RE₂Fe₁₄B principal phases are just divided into point.In addition, to meet different demagnetization environment to the demand of permanent magnet applications, it is necessary to use Dy, The heavy rare earth elements such as Tb partly substitute Nd, to improve the HCJ of magnet, replace part Fe and are moved back with improving the anti-of magnet Magnetic energy power.So, the chemical molecular formula of the principal phase of Nd Fe B alloys is just often expressed as RE₂M₁₄B, wherein, RE represent with Nd is the rare earth element of main component, and other such as Pr, Dy, Tb, Gd, Ho rare earth elements；M is represented using Fe as main component Transiting group metal elements, and other elements such as Co, Cu, Al, Ga, Nb etc..If being expressed as the form of percentage by weight, neodymium The chemical composition of ferroboron is：RE_xM_100-x-yB_y.Wherein, x is exactly the total amount of rare earth of Nd Fe B alloys, for sintered NdFeB Permanent-magnet material, common total amount of rare earth x=28~35%wt..If total amount of rare earth is less than 28%wt., Nd-rich phase very little, is prepared The magnet of high HCJ is just highly difficult；If total amount of rare earth is more than 35%wt., Nd-rich phase is too many, is difficult to prepare high remain Magnetic, high energy product, the sintered Nd-Fe-B permanent magnet of high corrosion-resistant.

Existing Nd-Fe-B permanent magnet production technology is usually to be equipped with required various alloying elements by a certain percentage Afterwards, it is placed in vacuum medium frequency induction furnace and melts uniform, then pours into the laminar ingot casting that thickness is 0.1~0.5mm.It is such The crystallite dimension of laminar neodymium iron boron mother alloy ingot is a few micrometers to hundreds of microns.

Then, by the neodymium iron boron foundry alloy it is hydrogenated after be crushed to average particle size particle size for 3.0~5.0 μm of yardsticks, make Powder particle that must be all turns into monocrystal.So, the average particle size particle size and crystallite dimension of powder are all 3.0~5.0 μm.

Then, above-mentioned powder is placed on and applies the green briquette that definite shape is pressed into the die cavity in magnetic field outside.At this In process, all powder particle its easy magnetizing axis in the presence of external magnetic field is arranged along magnetic direction, applies sufficiently large immediately Press power causes this align of powder particle to be fixed up.Then, the green briquette suppressed is sintered at 1000~1100 DEG C, It is allowed to be densified, as magnet blank；Also need blank magnet carrying out one-level or second annealing processing at 450~950 DEG C if necessary, with Further optimize magnetic property；Then process is to be machined, shape, size needed for blank magnet is cut, is ground to, Also need to carry out surfacecti proteon processing if necessary；Finally, magnetized the permanent magnet product for obtaining using along direction of easy axis.

According to neodymium iron boron phasor, about 1155 DEG C of the fusing point of principal phase in Nd Fe B alloys, the fusing point about 450 of Nd-rich phase~ 600℃.The effect of Nd-rich phase can not only cause neodymium iron boron to have magnet and have high HCJ, moreover, because rich rare earth The fusing point of phase is far below principal phase so that magnet is easy to densification in 1000~1100 DEG C of sintering process.

From Principles of Metallography, during 1000~1100 DEG C of sintering densification, the Nd-rich phase largely melted It is enclosed in around main phase grain, causes main phase grain to grow up rapidly, be roughened.Sintering temperature is higher, sintering time is longer, and principal phase is brilliant Grain is thicker, crystal grain, and size is more uneven, and the performance of magnet will be deteriorated；On the contrary, if sintering temperature is too low, melting Nd-rich phase ratio is very few, then the densification degree of magnet is low, not only magnetic property is deteriorated, and mechanical strength and corrosion-resistant Performance is also very poor.Therefore, to obtain excellent permanent magnetism performance, it should just make it that the density of sintered magnet is as high as possible, it is simultaneously main Phase crystal grain is unlikely to too to grow up --- and the average-size of crystal grain should be thin better below 10 μm, and more.

For making high density, the Sintered NdFeB magnet of fine grain, existing technology is broadly divided into two classes：One is by neodymium It is all less than about 3.0 μm even 3.0 μm that particle size and crystallite dimension are crushed to after iron boron foundry alloy is hydrogenated, then about 1020 DEG C of sintering densifications so that the average-size of final magnet crystal grain refine to 5~10 μm.With it is traditional be crushed to 3.0~ The technology of 5.0 μm of yardsticks is compared, and because the specific surface area of powder increases, the oxidation activity of powder particle is sharply increased, made Journey needs expensive equipment with complicated technological measure to protect to prevent oxidation, and manufacturing cost is high, powder easily catches fire, operate Poor safety performance.Another technology is by toward refractory metal or the oxidation such as addition Nb, Mo, Ti, ZrO in Nd Fe B alloys Thing, as described in United States Patent (USP) US6527874B2 so that main phase grain border is by infusibility metal compound particles in sintering process Pinning, hinders growing up for main phase grain.The disadvantage of the technology is the refractory metal that is added and its compound is all non-magnetic Property phase, can significantly reduce the remanent magnetism and magnetic energy product of magnet.

In addition, in the neodymium iron boron magnetic body that the common rare earth total content made of prior art is 28~35wt.%, it is general Store-through is more than 1.0 μm of big block Nd-rich phase in many crystallite dimensions.These big block, nonmagnetic Nd-rich phases are only Only play a part of filling magnet interior void, the magnetic property of magnet is not contributed, only those are uniform, be continuously wrapped in master The Nd-rich phase of phase grain boundary is just contributed to the coercivity of magnet.Conversely, because Nd-rich phase is pole in Nd Fe B alloys The phase being easily corroded, the presence of these big block Nd-rich phases reduces the decay resistance of magnet；Secondly, nonmagnetic, Big block Nd-rich phase plays a part of the whole magnet magnetic moment of dilution, and its presence in magnet actually reduces permanent magnet Unit volume magnetic property；Further, since rare earth is cost highest constituent element in Nd Fe B alloys, these have to magnet performance The unhelpful big block Nd-rich phase of evil actually also add the manufacturing cost of Nd-Fe-B permanent magnet.Therefore, neodymium iron boron is reduced These big block, nonmagnetic Nd-rich phases in permanent magnet can not only significantly improve the magnetic property of magnet and corrosion-resistant spy Property, while the cost of raw material can also be reduced effectively.However, existing Nd-Fe-B permanent magnet manufacturing technology can not be all overcome in magnet Middle this difficulty that there is big block Nd-rich phase.

For example, CN1468319A proposes the method that is mixed with the Nd Fe B alloys powder of a variety of heterogeneities to change Enter pattern or the distribution of the Nd-rich phase of big bulk, because the Nd Fe B alloys powder of a variety of heterogeneities used in it is averaged Particle size is identical with average grain size, and all powder particle is all monocrystal, and with single direction of easy axis, is burning It is very easy to mutually annex and grow up between particle during knot；Also, it also can not fundamentally solve magnetic with described method There is this difficulty of big block Nd-rich phase in body.

The content of the invention

The purpose of the present invention is by being 28~35wt.%, average particle size particle size and crystal grain in common rare earth total content Size is all to add a kind of rare earth total content in 3.0~5.0 μm female (master) alloy powder of sintered NdFeB to be substantially less than female conjunction Bronze end, while method of its crystallite dimension also much smaller than the chilling Nd Fe B alloys adjuvant powders of its particle size, suppresses neodymium The fast growth of crystal grain occurs in sintering process for iron boron pressed compact, reduces big block Nd-rich phase on neodymium iron boron principal phase border Produce, acquisition manufacturing cost is low, high performance Nd-Fe-B permanent magnet.

What the present invention was realized in：A kind of preparation method of sintered Nd-Fe-B permanent magnet, this method is to use foundry alloy With the dual alloy method of assistant alloy, it is characterised in that：The crystallite dimension of the assistant alloy is 0.01~0.1 μm.

Preferably, the foundry alloy and assistant alloy are RE-M-B alloys, contain RE₂M₁₄B phases, wherein RE are rare earth member Element, M is transiting group metal elements.

Preferably, the assistant alloy rare earth elements total content is 16wt.%~28wt.%.

Preferably, the rare earth element in the assistant alloy is free of heavy rare earth element.

Preferably, the foundry alloy rare earth elements total content is 28~35wt.%

Preferably, the ratio that the assistant alloy accounts for total alloy is 0.1wt.%~5wt.% percentage by weights.

Preferably, the foundry alloy and assistant alloy are ground into the powder of 3.0~5.0 μm of average particle size particle size.

Preferably, powder is mixed after the foundry alloy and assistant alloy can be crushed through airflow milling, or airflow milling is crushed again after mixed powder.

Preferably, the assistant alloy uses rapid hardening thin slice technique melting.

Preferably, the crystallite dimension of the foundry alloy is 3.0~5.0 μm.

Rare earth total content between 16wt.%~28wt.%, average grain size be 0.1~0.01 μm, average grain Size is in 3.0~5.0 μm of chilling neodymium iron boron assistant alloy powder, each size is 3.0~5.0 μm of powder particle Contain tiny crystal grains of many sizes for 0.1~0.01 μm of disorientation.This tiny crystal grains containing disorientation Powder particle, is all 3.0~5.0 μm of the foundry alloy powder with single direction of easy axis with average particle size particle size and crystallite dimension Last particle is compared, during 1000~1100 DEG C of sintering densification, it is not easy to fast growth.Therefore, by common Rare earth total content is that 28~35wt.%, average particle size particle size and crystallite dimension are all 3.0~5.0 μm of the main powder of sintered NdFeB Added in end another a small amount of rare earth total content be 16~28wt.%, average grain size be 0.1~0.01 μm, it is average Particle size is 3.0~5.0 μm of chilling neodymium iron boron assistant alloy powder, it is possible to suppress neodymium iron boron pressed compact in sintering process Occurs the fast growth of crystal grain；Also, by a small amount of inherently low rare earth of chilling assistant alloy powder added The Nd Fe B alloys of total amount, can absorb big block Nd-rich phase pernicious, so, not only in sintering process The remanent magnetism of final neodymium iron boron magnetic body is not damaged, and the maximum magnetic energy product and demagnetization curve rectangularity of magnet are significantly improved on the contrary, so that Inexpensive, the high performance sintered Nd-Fe-B permanent magnet of manufacture.

Brief description of the drawings

Fig. 1 is the schematic diagram of the sintered Nd-Fe-B alloy powder particle generally manufactured；

Fig. 2 is that the microstructure after Nd-Fe-B permanent magnet internal grain caused by the sintering process that generally manufactures is grown up is shown It is intended to；

The schematic diagram for the chilling neodymium iron boron assistant alloy powder particle that Fig. 3 is added for the present invention；

After the chilling neodymium iron boron assistant alloy powder particle that Fig. 4 with the addition of for the present invention, the neodymium iron caused by sintering process Boron permanent magnet internal grain grow up after microstructure schematic diagram；

The Nd-Fe-B permanent magnetic that Fig. 5 is sintered into after the assistant alloy powder to add different content in foundry alloy D powder The performance of body.

Embodiment

The embodiment according to the present invention is illustrated below with reference to accompanying drawings.

First, neodymium iron boron master (mother) alloy that rare earth total content is 28~35wt.% is made with common method of smelting, then Foundry alloy is ground into after over hydrogenation to average particle size particle size with airflow milling and crystallite dimension is all 3.0~5.0 μm of master alloy powder；

Rapid hardening thin slice technique, or chilling method of smelting is used to prepare the chilling that rare earth total content is 16wt.%~28wt.% again Neodymium iron boron assistant alloy, then the assistant alloy is ground into after over hydrogenation with airflow milling average grain size for 0.1~ 0.01 μm, the assistant alloy powder that average particle size particle size is 3.0~5.0 μm；

After the above-mentioned master alloy powder and assistant alloy powder of certain weight ratio are sufficiently mixed uniformly in meal mixer, Be orientated under magnetic field it is compressing, the pressed compact being pressed into after high temperature sintering again by second annealing processing obtain magnet.

Measure the magnetic property of magnet at 20 DEG C with Hysteresisgraph, including remanent magnetism, coercivity, magnetic energy product and Flex point coercivity.The density of magnet is measured simultaneously.

To make full use of the magnetocrystalline anisotropy of Nd Fe B alloys, it is desirable to which the easy magnetizing axis of all powder particles is along same Direction is arranged so that the permanent magnetism performance of magnet is most strong.To reach this purpose, it is necessary to control the smelter of neodymium iron boron foundry alloy Skill so that the crystallite dimension of prepared neodymium iron boron foundry alloy is more than 3.0~5.0 μm of the target average-size of powder particle.This Sample, could cause each powder particle to be monocrystal by subsequent pulverizing process, that is to say, that the particle size of powder It is identical with crystallite dimension.

And in order to obtain higher coercivity, remanent magnetism, high energy product simultaneously, obtain the sintered NdFeB permanent magnet of high corrosion-resistant Body, the rare earth total content of foundry alloy is preferably controlled in 28~35wt.%.

In the melting process of assistant alloy, by the Nd Fe B alloys of melting rapidly cooled and solidified, crystal grain pole just can obtain Its fine Nd Fe B alloys ingot casting, then it is that can obtain average grain size for 0.1~0.01 μ that it is crushed with airflow milling equipment M, average particle size particle size are 3.0~5.0 μm of chilling Nd Fe B alloys powder.When the total amount of rare earth of assistant alloy is more than During 25wt.%, resulting quick cooling alloy is mainly made up of neodymium iron boron principal phase and Nd-rich phase, and with the increasing of total amount of rare earth Greatly, Nd-rich phase is more and thicker, is distributed also more uneven；When the total amount of rare earth of assistant alloy is less than 25wt.%, gained The quick cooling alloy arrived is mainly by neodymium iron boron principal phase and α-Fe phase compositions, and with the reduction of total amount of rare earth, and α-Fe are mutually also more And it is thicker, it is distributed also more uneven.Here it is the total amount of rare earth of the described chilling neodymium iron boron assistant alloy of present invention selection is excellent The reason for being selected in not less than 16wt.%, not larger than 28wt.%.

The pulverizing process of Nd Fe B alloys is completed usually using airflow milling equipment, and the powder thus made is by largely not Particle with size is constituted, that is to say, that it is in a distribution within the specific limits that the particle size of Nd Fe B alloys powder, which is, The average particle size particle size of powder commonly employed in the art represents the particle size of Nd Fe B alloys powder, or granularity.Together Reason, it is in a distribution, the average crystal grain chi of powder commonly employed in the art within the specific limits that the crystallite dimension of powder, which is also, The very little crystallite dimension to represent Nd Fe B alloys powder, or grain size.

It is specific embodiment below.

Table 1 is the weight percent composition formula of master alloying and assistant alloy used in each embodiment and comparative example.Wherein Alloy A is neodymium iron boron master (mother) alloy that the rare earth total content made of common method of smelting is 32wt.%；Alloy B is this Invention chilling method of smelting makes, crystallite dimension is 0.1~0.01 μm and rare earth total content (26.8wt.%) is significantly low In alloy A assistant alloy；Alloy C be present invention chilling method of smelting make, crystallite dimension be 0.1~0.01 μm and Rare earth total content (23.2wt.%) is substantially less than RE₂Fe₁₄B's is just divided into point and containing the assistant alloy of part α-Fe phases.

Table 1

Embodiment 1

Dispensing is carried out by the middle rare earth total content TRE=32.0wt.% of table 1 alloy A first, then with common melting side Legal system is made foundry alloy, then crushes foundry alloy with airflow milling after over hydrogenation and forms master alloy powder, the crystal grain chi of powder Very little is 3.0~5.0 μm；Dispensing is carried out by the middle rare earth total content TRE=26.8wt.% of table 1 alloy B, chilling method of smelting is used Assistant alloy thin slice is fabricated to, assistant alloy powder is obtained by being crushed again with airflow milling after the direct coarse crushing of assistant alloy thin slice, The crystallite dimension of the assistant alloy powder is 0.1~0.01 μm.Alloy A and alloy B powder average particle size is 3.6 μm.

By weight fraction for 98wt.% alloy A powder and 2wt.% alloy B powder in meal mixer fully mix After closing uniformly, it is orientated under 1.95T magnetic fields, 0.8t/cm²It is compressing under pressure, size is sintered into for 51*51*25mm through 1050 DEG C Magnet, then in 900 DEG C and 480 DEG C of second annealings.Magnetic property data are measured to the magnet being made, as a result as shown in table 2.

Comparative example 1

Alloy A single in embodiment 1 powder is orientated under 1.95T magnetic fields, 0.8t/cm²It is compressing under pressure, The magnet that size is 51*51*25mm is sintered into through 1050 DEG C, then in 900 DEG C and 480 DEG C of second annealings.To the magnet being made Magnetic property data are measured, as a result as shown in table 2.

It can see from the data of table 2, embodiment 1 is added in the main powder of common Nd Fe B alloys and accounts for total amount 2wt.% Without after heavy rare earth and the relatively low assistant alloy B powder with fine-grain of total amount of rare earth, made magnet is in remanent magnetism Br In the case of being basically unchanged, coercivity H j, maximum magnetic energy product (BH) m and demagnetization curve rectangularity Hk/Hcj are significantly improved. This is due to that common Nd Fe B alloys powder particle is all monocrystal, and its internal crystal framework does not have defect, as shown in Figure 1, its The middle direction of easy axis that intra-die is represented with block arrow, 1 represents principal phase, and 2 represent Nd-rich phase.In the process of high temperature sintering In, it is easy to occur between the powder particle closed on mutually to annex and grow up, be roughened.Due to the mutual annexation between this crystal grain The long local energy that receives greatly rises and falls influence, has resulted in the uneven of crystallite dimension in final sintered magnet, as shown in Figure 2.

Theory and practice proves, the crystal grain of neodymium iron boron magnetic body is more tiny, size is more uniform, its coercivity H j, maximum magnetic energy The squareness of product (BH) m and demagnetizing curve is higher.By the powder of the alloy B of the invention added is that average grain size is The brilliant particle of 0.1~0.01 μm of fine chilling, as shown in Figure 3, contains several easy magnetizations inside each powder particle Direction of principal axis small grains at random, during high temperature sintering, due to the crystalline substance between the fine-grain inside the brilliant particle of chilling Lattice are inconsistent, and it, which is mutually annexed, grows up and become the completely the same monocrystal needs of lattice very big energy；In addition, because principal phase RE₂Fe₁₄About 1155 DEG C of B fusing point, and the fusing point of Nd-rich phase only has about 450~600 DEG C, in 1050 DEG C of sintering process, Also it is not easy inside the brilliant particle of fine chilling in the alloy B adjuvant powders that total amount of rare earth is low thus Nd-rich phase ratio is seldom Form micro- molten bath and fast growth.So, what the present invention was added has the brilliant alloy B adjuvant powders of fine chilling made The neodymium iron boron pressed compact made plays the role of to suppress other regular grain growths, such as the institute of accompanying drawing 4 during identical high temperature sintering Show.Further, since the alloy B adjuvant powders with fine chilling crystalline substance that the present invention is added inherently have RE₂Fe₁₄B is brilliant The alloy of body structure, and addition is less than 5wt.%, and influence is nearly free from the remanent magnetism of final magnet.

Normally, it is all 0.1~1 μm containing a certain proportion of crystallite dimension and particle size in conventional master alloy powder The powder of scope, if the crystallite dimension of auxiliary powder is more than 0.1 μm, it does not have the effect for suppressing other regular grain growths； If aiding in the crystallite dimension of powder to be less than~0.01 μm, that is, nanoscale, then manufacturing process complex, cost are high, practice In be difficult to.

Compared with comparative example 1, embodiments of the invention 1 are in the case where remanent magnetism Br is basically unchanged, coercivity H j, maximum Magnetic energy product (BH) m and demagnetization curve rectangularity are all significantly improved, and total rare earth weight ratio in magnet, particularly weigh dilute Native Dy ratio is decreased, and the manufacturing cost of magnet is just reduced simultaneously.

If that is added there is the brilliant alloy B adjuvant powders ratio of fine chilling to be more than 5wt.%, due to the tool after sintering The easy magnetizing axis for having the brilliant particle of fine chilling will be generally offset from the easy magnetizing axis of other main phase grains, will significantly reduce final The remanent magnetism of magnet.If on the contrary, that is added there is the brilliant alloy B adjuvant powders ratio of fine chilling to be less than 0.1wt.%, its The effect for suppressing other regular grain growths is not just notable.Therefore, the described low total amount of rare earth of the preferred addition of the present invention has The brilliant assistant alloy powder ratio of fine chilling is 0.1wt.%~5wt.%.

Embodiment 2

The preparation of the master alloy powder (alloy A powder) used in embodiment 2 and assistant alloy powder (alloy B powder) Journey, crystallite dimension and particle mean size are identical with embodiment 1.By the alloy A powder and 2wt.% that weight fraction is 98wt.% Alloy B adjuvant powders be sufficiently mixed in meal mixer it is uniform after, be orientated under 1.95T magnetic fields, 0.8t/cm²Suppressed under pressure Shaping, sinters the magnet that size is 51*51*25mm into, then in 900 DEG C and 480 DEG C of second annealings through 1070 DEG C.To what is be made Magnet measures magnetic property data, as a result as shown in table 2.

Comparative example 2

Alloy A single in embodiment 2 powder is orientated under 1.95T magnetic fields, 0.8t/cm²It is compressing under pressure, The magnet that size is 51*51*25mm is sintered into through 1070 DEG C, then in 900 DEG C and 480 DEG C of second annealings.To the magnet being made Magnetic property data are measured, as a result as shown in table 2.

As known to the professional of the industry, neodymium iron boron pressed compact in high-temperature sintering process, crystal grain grow up to burn Junction temperature is very sensitive.If sintering temperature is slightly higher, crystal grain will drastically grow up, coercivity H j, the maximum magnetic flux of final magnet Energy product (BH) m and demagnetization curve rectangularity will deteriorate.Therefore, in the manufacturing process of Sintered NdFeB magnet, sintering is set Have very high temperature control precision requirement.

From the data of table 2 it will be clear that in sintering temperature after 1050 DEG C bring up to 1070 DEG C, with comparative example 1 compares, because crystal grain is drastically grown up, coercivity H j, maximum magnetic energy product (BH) m and the demagnetizing curve of the final magnet of comparative example 2 Squareness is all significantly reduced.On the contrary, that is added in embodiments of the invention 2 has the brilliant alloy B auxiliary powder of fine chilling End plays the role of to suppress other regular grain growths, after being sintered beyond nominal sintering temperature up to same time at 1070 DEG C of 20 DEG C Still there is good coercivity H j, maximum magnetic energy product (BH) m and demagnetization curve rectangularity.This explanation is using method of the invention Afterwards, the temperature control precision of agglomerating plant is required to reduce, the equipment cost and process management cost of sintering circuit can be reduced.

Embodiment 3

Mother is made with alloy A identicals, the method for smelting by routine in table 1 for 98wt.% composition in weight fraction The coarse powder obtained after alloy after break process in hydrogenation, with 2wt.% composition with alloy B identicals in table 1, through over-quenching Method of smelting be fabricated to after assistant alloy thin slice without hydrotreated coarse powder be sufficiently mixed in meal mixer it is uniform after, will be described Mixture is crushed by airflow milling again, and the powder that particle mean size is 3.4 μm is made in the lump.Then it is orientated under 1.95T magnetic fields, 0.8t/cm²It is compressing, the magnet that size is 51*51*25mm is sintered into through 1050 DEG C, then in 900 DEG C and 480 DEG C two grades It is as shown in table 2 with automatic survey magnetic device measurement magnetic property data after tempering.

It can be seen that, compared with comparative example 1, the coercivity H j of the final magnet of embodiments of the invention 3, maximum magnetic energy Product (BH) m and demagnetization curve rectangularity are obtained for and increased substantially.

Embodiment 4

The assistant alloy C made with quenching method by weight fraction as shown in table 1 for 98% alloy A and 2% exists After being sufficiently mixed in meal mixer uniformly, in the lump by hydrogenation treatment, then by the mixture, process airflow milling is crushed again, is made in the lump Into the powder that particle mean size is 3.4 μm.Described assistant alloy C is the method for smelting making of present invention chilling, crystal grain chi Very little is 0.1~0.01 μm of rare earth total content substantially less than RE₂Fe₁₄B's is just divided into point and containing the alloy of part α-Fe phases. Then it is orientated under 1.95T magnetic fields, 0.8t/cm²It is compressing, sinter the magnet that size is 51*51*25mm into through 1050 DEG C, It is as shown in table 2 with automatic survey magnetic device measurement magnetic property data then after 900 DEG C and 480 DEG C of second annealings.

It can be seen that, compared with comparative example 1, the remanent magnetism of the final magnet of embodiments of the invention 4, coercivity H j, maximum Magnetic energy product (BH) m and demagnetization curve rectangularity Hk/Hcj are obtained for and increased substantially.

Here pay particular attention to, the total amount of rare earth in described assistant alloy C is 23.2%wt., already below RE₂Fe₁₄B Be just divided into point, also there is part α-Fe in alloy C now in addition to principal phase.Due to alloy C be made with quenching method, its Crystallite dimension is 0.1~0.01 μm, very fine, in 1050 DEG C of sintering processes, is occurred in the α-Fe of fine-grain state same Plain isomeric transition turns into γ-Fe phases, and by occurring peritectic reaction with the liquid Nd-rich phase in master alloying, forms RE₂Fe₁₄B Phase.That is, by adding total amount of rare earth less than RE₂Fe₁₄The B Quench alloy C being just divided into point, can be by common rare earth Total content absorbs for big block Nd-rich phase pernicious to magnet performance in 28~35wt.% Nd Fe B alloys, and Transform into normal RE₂Fe₁₄B principal phases.So, significantly improved equivalent to the principal phase ratio in total component of magnet , therefore the remanent magnetism of magnet is also significantly improved；Also, by the Quench alloy C particles in fine-grain state added are burning Growing up for alloy A particles is inhibited during knot, so the coercivity H j of magnet, maximum magnetic energy product (BH) m and demagnetizing curve side Shape degree, which is obtained for, to be increased substantially.

Table 2

Embodiment 5

Dispensing is carried out by the middle rare earth total content TRE=32.0wt.% of table 3 alloy D, then with common method of smelting system Foundry alloy is made, then foundry alloy is crushed after over hydrogenation with airflow milling and forms master alloy powder, the average crystal grain chi of powder Very little is 3.5 μm, and average particle size particle size is also 3.5 μm；Matched somebody with somebody by the middle rare earth total content TRE=26.8wt.% of table 1 alloy B Material, is fabricated to assistant alloy thin slice with chilling method of smelting, will be crushed again with airflow milling after the direct coarse crushing of assistant alloy thin slice Assistant alloy powder is obtained, the crystallite dimension of the assistant alloy powder is 0.1~0.01 μm, and average particle size particle size is 3.5 μm.

Addition accounts for total amount 0wt.%, 1.0wt.%, 1.5wt.%, 2.5wt.% respectively in the powder of the foundry alloy D With 5.0wt.% alloy B powder, and be sufficiently mixed respectively in meal mixer it is uniform after, be orientated under 1.95T magnetic fields, 0.8t/cm²It is compressing under pressure, sintered one hour through 1050 DEG C, sinter the magnet that size is 51*51*25mm, Ran Hou into 900 DEG C and 480 DEG C are tempered one hour respectively.Magnetic property data are measured to the magnet being made, as a result as shown in Figure 5.

Table 3

	Nd	Pr	Dy	B	Co	Cu	Al	Ga	TRE	Fe
											Alloy D	21.5	6.0	1.5	1.0	1.0	0.1	0.3	0.1	32.0	Surplus

In figure 5, abscissa represents the addition (percentage by weight) of alloy B powder, and the ordinate on Fig. 5 left sides is represented Remanent magnetism Br, the coercivity H j and maximum magnetic energy product (BH) m of magnet, the ordinate on the right represent the flex point coercivity Hk of magnet.

From accompanying drawing 5 it will be clear that：With the increase of the addition of alloy B powder, the remanent magnetism Br of magnet is almost protected Hold constant, and the coercivity H j of magnet, maximum magnetic energy product (BH) m are then incrementally increased, and especially, characterize magnet demagnetization curve side The flex point coercivity Hk of shape degree index is significantly increased；But when the addition of alloy B powder is more than 2.5wt.%, for example, reach During 5.0wt.%, every magnetic property index of magnet no longer increases with the increase of the addition of alloy B powder.Therefore, this hair The bright total amount of rare earth preferably added in master alloy powder is less than the assistant alloy that 28wt.%, crystallite dimension are 0.1~0.01 μm The weight fraction of powder is 0.1~5.0wt.%.

The worker of this area it should be clear that in each embodiment explained above, with a small amount of low total amount of rare earth of addition, Powder is aided in another brilliant neodymium iron boron of fine chilling, to suppress growing up in sintering process other normal crystal grain, from And it is identical to manufacture low cost, the principle of the sintered Nd-Fe-B permanent magnet product of high-quality.

The sintering neodymium according to manufacture low cost disclosed in this invention, high-quality has been explained in detail with reference to the accompanying drawings above The principle and method of iron boron permanent magnet product, thus those skilled in the art can be by according to principles of this disclosure and method Manufacture sintered Nd-Fe-B permanent magnet and be applied to various fields, such as applied to various computer drives, industrial and civilian electricity In machine, applied to various loudspeakers, sensor, electric motor of automobile and various Medical Instruments and industrial automation equipment, instrument Driving part etc..

Multiple embodiments of the present invention have been explained in detail with reference to the accompanying drawings above, but above embodiment is only to this Schematically illustrating for invention is not intended to limit the present invention.In addition, though being that each embodiment is carried out in independent, separated form above Illustrate, but those skilled in the art should be aware that above-mentioned multiple embodiments can also be applied in combination.And this area skill The technology that art personnel can combine existing conventional manufacture permanent magnet upon reading the above description makes various repair to the present invention Change and change, this modifications and variations are also fallen within the scope and spirit of the invention.

Claims

1. a kind of preparation method of sintered Nd-Fe-B permanent magnet, this method is the dual alloy side using foundry alloy and assistant alloy Method, it is characterised in that：The crystallite dimension of the assistant alloy is 0.01~0.1 μm,

The foundry alloy and assistant alloy are RE-M-B alloys, contain RE₂M₁₄B phases, wherein RE are rare earth element, and M is transition group Metallic element.

2. the preparation method of sintered Nd-Fe-B permanent magnet as claimed in claim 1, it is characterised in that：It is dilute in the assistant alloy Earth elements total content is 16wt.%~28wt.%.

3. the preparation method of sintered Nd-Fe-B permanent magnet as claimed in claim 2, it is characterised in that：In the assistant alloy Rare earth element is free of heavy rare earth element.

4. the preparation method of sintered Nd-Fe-B permanent magnet as claimed in claim 1, it is characterised in that：The foundry alloy middle rare earth Element total content is 28~35wt.%.

5. the preparation method of sintered Nd-Fe-B permanent magnet as claimed in claim 1, it is characterised in that：The assistant alloy is accounted for always The ratio of alloy is 0.1wt.%~5wt.% percentage by weights.

6. the preparation method of sintered Nd-Fe-B permanent magnet as claimed in claim 1, it is characterised in that：The foundry alloy and auxiliary Alloy is ground into the powder of 3.0~5.0 μm of average particle size particle size.

7. the preparation method of sintered Nd-Fe-B permanent magnet as claimed in claim 1, it is characterised in that：The foundry alloy and auxiliary Alloy mixes powder after being crushed through airflow milling, or airflow milling is crushed again after mixed powder.

8. the preparation method of sintered Nd-Fe-B permanent magnet as claimed in claim 1, it is characterised in that：The assistant alloy is used Rapid hardening thin slice technique melting.

9. the preparation method of sintered Nd-Fe-B permanent magnet as claimed in claim 1, it is characterised in that：The crystal grain of the foundry alloy Size is 3.0~5.0 μm.