CN100474460C - Sintering rear-earth permanent-magnetic alloy and manufacturing method thereof - Google Patents

Sintering rear-earth permanent-magnetic alloy and manufacturing method thereof Download PDF

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CN100474460C
CN100474460C CNB200510070730XA CN200510070730A CN100474460C CN 100474460 C CN100474460 C CN 100474460C CN B200510070730X A CNB200510070730X A CN B200510070730XA CN 200510070730 A CN200510070730 A CN 200510070730A CN 100474460 C CN100474460 C CN 100474460C
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alloy
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CN1694188A (en
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李正
何叶青
胡伯平
王亦忠
王震西
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SANHUAN NEW-MATERIAL HIGH-TECHNOLOGY Co BEIJING
Beijing Zhong Ke San Huan High Tech Co Ltd
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SANHUAN NEW-MATERIAL HIGH-TECHNOLOGY Co BEIJING
Beijing Zhong Ke San Huan High Tech Co Ltd
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Abstract

This invention provides a kind of sintered lanthanon permanent magnet alloy and its manufacturing method. The sintered lanthanon permanent magnet alloy is sintered Nd-Fe-B permanent magnet, including antiferromagnetism transition series element Cr or Mn. Its magnetism performance parameter bounds are: the residual magnetism is no more than 1.1 T, the magnetic energy accumulate is 10 - 30 MGOe, coercive force after anneal heat treatment are no less than 15 kOe. The Nd-Fe-B permanent magnet provided by present invention has such advantages as low cost, good product uniformity, high manufacturing stability, simple manufacturing method, and needn't change the present Nd-Fe-B manufacturing equipments, is easy for controlling and large-scale industrialization manufacturing.

Description

Sintered rare earth permanent magnet alloy and manufacture method thereof
Technical field
The present invention relates to a kind of sintered Nd-Fe-B magnet, particularly relate to sintered Nd-Fe-B magnet and the manufacture method thereof of a kind of scope of magnetic energy product at 10～30MGOe.
Background technology
Since finding Nd-Fe-B the beginning of the eighties in last century, be Nd-Fe-B permanent magnetic material itself or its application technology has all obtained fast development.The Nd-Fe-B permanent magnetic material has been widely used in fields such as the voice coil motor of disc driver, all kinds of motor, Magnetic resonance imaging equipment, electro-acoustic element and magnetic machinery.The Nd-Fe-B magnet mainly contains sintered Nd-Fe-B and bonded Nd-Fe-B.The remanent magnetism B of Nd-Fe-B permanent magnet rAnd magnetic energy product (BH) MaxDetermine by following formula:
Br＝AfJ s(1-β)d/d 0
(BH) max＝Br 2/4μ rec (1)
Wherein, A is the volume fraction on forward farmland, and f is the degree of orientation, J sBe the saturation magnetization of magnet, β is non magnetic phase volume fraction, and d is the magnet actual density, d 0Be the ideal density of magnet, μ RecRecoil permeability for magnet.As can be seen, by saturation magnetization, principal phase ratio, relative density and the degree of orientation of control magnet, can control the remanent magnetism and the magnetic energy product of magnet.
Usually, the magnetic energy product of sintered nd-fe-b magnet is all more than 30MGOe.Because sintering process requirement, the relative density of magnet can not be too low, all can cause otherwise influence and increase the ratio of non magnetic phase, the saturation magnetization of the whole magnet of dilution and the degree of orientation of reduction magnet, therefore be difficult to obtain the sintered nd-fe-b magnet that magnetic energy product is lower than 30MGOe.At present, magnetic energy product mainly is Sm-Co (magnetic energy product is between 20～30MGOe) magnet and the bonded Nd-Fe-B magnet (magnetic energy product is between 10～20MGOe) made by the MQIII magnetic at the magnet of 10～30MGOe on the market.Because Sm only is about 1/4 of Nd at the content of the earth's crust, Co is expensive, rare strategic materials, mainly is distributed in some the west African states, and the market supply is very unstable, so the application of Sm-Co alloy is subjected to the restriction of these objective factors always.For bonded Nd-Fe-B magnet, because a variety of causes is far from the sintered nd-fe-b magnet development rapidly in recent years, its price is also not following according to height always.Therefore, many magnet applications manufacturers attempt to use sintered nd-fe-b magnet to replace or part replaces, expensive bonded Nd-Fe-B magnet that make by the MQIII magnetic, and expensive more Sm-Co magnet, reducing cost, thereby in market competition, get the mastery.
Yet, as previously mentioned, the sintered nd-fe-b magnet that uses prior art to make, its magnetic energy product is generally all more than 30MGOe, directly substitute the change that can cause the magnetic circuit characteristic, adapt to high performance Nd-Fe-B magnet and can cause change to requirements such as the components and parts relevant with magnetic circuit, assembly equipments and change magnetic circuit, this is that a lot of magnet applications manufacturer is undesirable.Over a period to come, some magnet applications manufacturers wish to use magnetic property quite but the lower permanent magnet of cost.In addition, coercive force is the important indicator that permanent magnet keeps magnetic property stability.Therefore, the general requirement of the application of permanent magnet has sufficiently high coercive force.In view of this, develop a kind of magnetic energy product,, satisfy the needs of some special permanent magnet applications, have the real world applications meaning to remedy the deficiencies in the prior art at 10～30MGOe, cheapness and sintered nd-fe-b magnet with higher coercivity.
As everyone knows, sintered Nd-Fe-B magnet is made with powder metallurgy method.Its manufacture process comprises: at first, produce alloy cast ingot with the method for vacuum metling; Secondly, alloyed powder is broken into the powder that particle mean size is 3～5 μ m; Then, in enough big external magnetic field, make powder particle align (orientation) in powder, and powder is pressed form piece simultaneously; At last, in vacuum furnace, sinter the orientation pressed compact into fine and close magnet.For the sintered nd-fe-b magnet that obtains to stablize, magnetic property is high, in the orientation suppression process, need to use enough big, magnetic is magnetized to the external magnetic field that approaches to saturation.At present, thereby some sintered Nd-Fe-B manufacturers adopt the method that reduces the orientation external magnetic field reduction degree of orientation, obtain the sintered Nd-Fe-B magnet of the scope of magnetic energy product at 10～30MGOe, and the result causes the demagnetization curve squareness extreme difference (referring to Fig. 2 b) of magnet.The squareness of permanent magnet is to weigh the trend of work stability of magnet in magnetic circuit, and magnet is to the important indicator of the stability of environmental change.In addition, when the orientation external magnetic field is reduced to can not make the saturated state of magnetic the time, the minor fluctuations of orientation external magnetic field promptly can cause the bigger variation of the pressed compact degree of orientation, thereby cause the final magnetic property fluctuation of magnet bigger, can't guarantee the consistency of magnet, cause product qualified rate lower, production cost is higher relatively.Simultaneously,, cause the local magnetic flux of permanent magnet inhomogeneous, bring all inconvenience and difficulty for the Application Design of magnet because the degree of orientation is inhomogeneous or inconsistent.
Also have some manufacturers to adopt and add a large amount of heavy rare earth (in the prior art, even add the heavy rare earth up to 10wt.%, the remanent magnetism of magnet also can only be reduced to about 1.05T) or add remanent magnetism and the magnetic energy product that methods such as a large amount of Mo, Nb reduce magnet.On the one hand, add alternative Nd such as heavy rare earth Dy, Tb, reduced the saturation magnetization of principal phase; On the other hand, the adding of elements such as Mo, Nb has consumed part B, forms some fusing point height, Bization thing that hardness is big, and the volume fraction of principal phase is reduced, and has diluted magnet, makes the permanent magnet of magnetic energy product at 10～30MGOe thereby reach.Yet, because heavy rare earth content is less relatively, produce relatively difficulty of heavy rare earth Dy or Tb, often cause a lot of byproducts, thereby the market price of heavy rare earth Dy, Tb etc. is always than higher.And the product that adds Mo, Nb in a large number can add and damage machining tool man-hour easily at inner a lot of Mass distributions, compound hard, that contain B of forming of magnet, reduces machining accuracy, causes the further increase of cost.Therefore, make magnetic energy product and all have shortcoming, caused that to make the permanent magnet cost with this magnetic property too high, well meeting the market requirement in the prior art of the permanent magnet of 10～30MGOe.
Thereby the character of adding element change alloy composition change material is the common method of made and modification.Open among the flat 4-268051 the Japanese patent gazette spy, for irreversible loss that reduces magnet and the thermal stability that improves magnet, almost added all rare earth elements and transition metal, but its purpose of adding rare earth element and transition metal is not in order to reduce the remanent magnetism of sintered Nd-Fe-B, thereby obtains magnetic energy product between 10～30MGOe and the magnet with higher coercivity.In the Nd-Fe-B magnet, the element substitution principal phase element beyond any Nd, Fe, the B all can reduce magnet remanent magnetism (referring to J.F.Herbst.Reviews of Modern Physics.Vol.63, No.4, in October, 1991,819-904).These substitute element can be divided into two classes substantially: a class reduces the remanent magnetism of magnet, reduces the coercive force of magnet simultaneously, for example Ni, C, La etc.; Another kind of reduction remanent magnetism, but can improve the coercive force of magnet, for example Dy, Tb, Nb, Cr etc.For how producing low remanent magnetism, high-coercive force, have the magnet of uniform temperature stability, and make with low cost, manufacture method is easy, does not still have disclosed feasible method up to now.Though a large amount of mixed rare earth alloys (mainly consisting of Ce, La) that add cheapness can reduce the remanent magnetism of magnet to a certain extent (referring to .Journal of Alloys and Compounds.298 (2000) such as H.R.Madaah Hosseini, 319-323), but the interpolation of mishmetal will reduce the coercive force of magnet (referring to J.F.Herbst.Reviews of Modern Physics.Vol.63, No.4, in October, 1991,819-904; And F.D.Saccone, H.Sirkin.Physica B:condensed Matter Volume 354.Issues 1-4,2004,209-212), cause a lot of situation lower magnets not use.
Summary of the invention
The objective of the invention is to overcome the difficulty that prior art faced of above-mentioned manufacturing magnetic energy product at the permanent magnet of 10～30MGOe, for example cost is higher relatively, magnet can not well meet application requirements etc., thus provide a kind of with low cost, be easy to control consistency, make that stability is high, magnetic energy product is at 10～30MGOe and meet the sintered Nd-Fe-B magnet and the manufacture method thereof of application requirements.
To achieve these goals, the invention provides a kind of sintered Nd-Fe-B magnet, this sintered Nd-Fe-B magnet comprises antiferromagnetism transition element Cr or Mn, its magnetic parameter scope is: remanent magnetism is smaller or equal to 1.1T, magnetic energy product is 10～30MGOe, and the coercive force after annealing heat treatment is more than or equal to 15kOe.
Sintered Nd-Fe-B magnet of the present invention, in this sintered Nd-Fe-B magnet, the content of antiferromagnetism transition element Cr or Mn is 0.5～20at.%.
Sintered Nd-Fe-B magnet of the present invention, this sintered Nd-Fe-B magnet is made up of Nd, Fe, B and Cr, perhaps is made up of Nd, Fe, B and Mn.
Sintered Nd-Fe-B magnet of the present invention, this sintered Nd-Fe-B magnet also comprises Dy or Tb.
Sintered Nd-Fe-B magnet of the present invention, the content of Dy or Tb is smaller or equal to 5.0at.%.
To achieve these goals, the present invention also provides a kind of method of making sintered Nd-Fe-B magnet, the method of this manufacturing sintered Nd-Fe-B magnet may further comprise the steps: the preparation alloy cast ingot, and wherein, this alloy cast ingot comprises antiferromagnetism transition element Cr or Mn; This alloy cast ingot is ground into powder; Be orientated this powder in the outside magnetic field, and its pressure is formed block pressed compact; Sintering should the bulk pressed compact, and the heat treatment of annealing, form this sintered Nd-Fe-B magnet, wherein, the magnetic parameter scope of this sintered Nd-Fe-B magnet is: remanent magnetism is smaller or equal to 1.1T, and magnetic energy product is 10～30MGOe, and coercive force is more than or equal to 15kOe, wherein, this sintered Nd-Fe-B magnet is by Nd, Fe, B and Cr form, perhaps by Nd, Fe, B and Mn form, wherein, during the preparation alloy cast ingot, use low-purity metal element Cr or Mn, perhaps use Cr-Fe alloy or Mn-Fe alloy, wherein, in described low-purity metal element Cr or Mn, the purity of Cr or Mn is lower than 91at.%.
The method of manufacturing sintered Nd-Fe-B magnet of the present invention, in this sintered Nd-Fe-B magnet, the content of antiferromagnetism transition element Cr or Mn is 0.5～20at.%.
The method of manufacturing sintered Nd-Fe-B magnet of the present invention, this sintered Nd-Fe-B magnet is made up of Nd, Fe, B and Cr, perhaps is made up of Nd, Fe, B and Mn.
The method of manufacturing sintered Nd-Fe-B magnet of the present invention during the preparation alloy cast ingot, can be used low-purity metal element Cr or Mn, perhaps uses Cr-Fe alloy or Mn-Fe alloy.
The method of manufacturing sintered Nd-Fe-B magnet of the present invention, in described low-purity metal element Cr or Mn, the purity of Cr or Mn is lower than 90at.%.
The method of manufacturing sintered Nd-Fe-B magnet of the present invention, this sintered Nd-Fe-B magnet also comprises Dy or Tb.
The method of manufacturing sintered Nd-Fe-B magnet of the present invention, the content of Dy or Tb is smaller or equal to 5.0at.%.
To achieve these goals, the present invention also provides a kind of sintered Nd-Fe-B magnet of making according to the method for above-mentioned manufacturing sintered Nd-Fe-B magnet.
The present invention adopts and adds antiferromagnetic transition element (AF=Cr, method Mn) (preferentially using Cr) make antiferromagnetic element enter sintered nd-fe-b magnet principal phase and crystal boundary mutually, have reduced the remanent magnetism and the magnetic energy product of magnet, have improved the coercive force of magnet simultaneously.That the present invention has is with low cost, consistency of product good, make that stability is high, manufacture method is simple, need not to change existing sintered Nd-Fe-B manufacturing equipment, be easy to control, realize advantage such as large-scale industrial production easily.By method provided by the invention, can access magnetic energy product between 10～30MGOe, the sintered nd-fe-b magnet that has higher coercivity (being issued to 19kOe) and have uniform temperature stability in the situation of not adding any heavy rare earth element.
Description of drawings
Fig. 1 is the demagnetization curve of sintered state (without sintering heat treatment) Nd-Fe-Cr-B magnet;
Fig. 2 a is the demagnetization curve through Nd-Fe-Cr-B magnet after 620 ℃ of annealing heat treatments;
Fig. 2 b is the demagnetization curve of the suitable magnet of the magnetic property of employing reduction degree of orientation acquisition;
Fig. 3 a is the back scattering SEM figure of Cr content Nd-Fe-Cr-B magnet when being 2.2wt.%;
Fig. 3 b is the principal phase EDAX results of the magnet among Fig. 3 a;
Fig. 3 c is the rich Nd phase EDAX results of the magnet among Fig. 3 a;
Fig. 4 is the alternating temperature demagnetization curve of Cr content Nd-Fe-Cr-B magnet when being 1.5wt.%.
Embodiment
Below in conjunction with Fig. 1～Fig. 3, the present invention is described in detail.
The present invention uses and adds antiferromagnetism transition element (AF=Cr, Mn) method reduces the remanent magnetism and the magnetic energy product of sintered Nd-Fe-B magnet, and improve the coercive force of magnet, thereby the remanent magnetism that makes magnet is reduced to 1T even lower, magnetic energy product is 10～30MGOe, makes coercive force reach 19kOe under the situation of not adding any heavy rare earth element.If add a spot of Dy or Tb simultaneously, can more effectively improve the coercive force of magnet, and further widen the scope of magnetic energy product.
In fusion process or pulverizing process, add antiferromagnetism transition element (AF=Cr, Mn) metal or its alloy, make principal phase that antiferromagnetism transition element Cr, Mn enter into sintered nd-fe-b magnet and rich Nd mutually, thereby reduce the saturation magnetization (entering the principal phase part) of principal phase, reach and make the permanent magnet of magnetic energy product, and improve the purpose of coercive force (enter rich Nd and partly improved micro-structural mutually) in 10～30MGOe scope.Wherein, the content of sintered nd-fe-b magnet antiferromagnetism transition element Cr, Mn is 0.5～20at.%.
The present invention is less demanding to purity of raw materials.For Cr, the embodiment of the invention 1 employed purity of raw materials has only 91%, also can use little carbon Cr-Fe alloy.In embodiment 2 and embodiment 3, employing be little charcoal Cr-Fe alloy.Block raw material such as Nd, Pr only need to clean its surface with alcohol or gasoline and can use.
Can only contain Nd, Fe, B, Cr (perhaps Mn) in the resulting sintered Nd-Fe-B magnet.Elements such as Pr, Dy, Tb, Nb, Co, Cu, Al can not add or add on a small quantity, and C can be used as impurity and enters into magnet.The preferable content of each element is: Pr, 1～20at.%; Dy, 0.2～2at.%; Co, 0.5～30at.%; Al, 0.1～3at.%; Cu, 0.05～1at.%.For heavy rare earth elements such as expensive Dy, Tb, can not use or the minute quantity use.
Embodiment 1
Present embodiment adopts the method for pairing gold to make magnet.It is R that master alloying adopts composition 14.5(Fe, TM) 79.5B 6(R=Nd, Pr, Dy, Tb; TM=Co, Cu, Al, Nb etc.) ingot casting, secondary alloy adopts the method for electric arc melting to obtain, its composition is R 14.5(Fe, TM, Cr) 79.5B 6(R=Nd, Pr, Dy, Tb; TM=Co, Cu, Al, Nb etc.).Put into two stainless cylinder of steels respectively and carry out hydrogen fragmentation (HD), after the hydrogen fragmentation according to certain mixed powder, carry out airflow milling then, in magnetic field is orientation and moulding under the 2T, add static pressure such as 200MPa, the last sintering that carries out under 1000～1100 ℃ vacuum state, the magnet that obtains was annealed 5 hours down at 620 ℃.Table 1 has been listed the magnetic property of the magnet of different Cr content.
Use MagnetPhysik permanent magnetism measuring system and NIM-10000H type permanent magnetic material measurement mechanism (China National Measuring Science Research Inst.'s system) to measure the demagnetization curve of sintered state and annealing back magnet.Use the LEO-1450 scanning electron microscopy to carry out microstructure binding energy analysis of spectrum.
Table 1
The content of Cr (wt.%) Br(kGs) H cj(kOe) (BH) max(MGOe) H k/H cj
0 12.71 9.3 38.07 0.89
0.2 13.25 8.9 38.12 0.71
0.6 12.65 8.8 37.46 0.92
1.5 10.97 11.40 28.57 0.82
2.2 10.43 11.20 25.88 0.80
Fig. 1 has provided the room temperature demagnetization curve of the sintered state Nd-Fe-Cr-B magnet that embodiment 1 obtains, and this figure is without the heat treated demagnetization curve of sintering.After the process sintering heat treatment of uniform temperature, coercive force can increase 5～7kOe usually.Can see, the interpolation of minute quantity antiferromagnetism transition element Cr, the magnetic property of magnet changes little.Along with increasing of Cr, the remanent magnetism of magnet sharply reduces.When the content of Cr reached 1.5wt.%, the remanent magnetism of magnet was reduced to 1.097T, and magnetic energy product is less than 30MGOe, and the coercive force ratio does not enlarge markedly when not adding Cr.When Cr increased to 2.2wt.%, the coercive force of sintered state magnet decreased, and remanent magnetism and magnetic energy product all continue to reduce.If the content of Cr continues to increase, then remanent magnetism and magnetic energy product all will further reduce.
Fig. 2 a is the demagnetization curve after the sintered Nd-Fe-Cr-B magnet when Cr is 2.2wt.% among the embodiment 1 was annealed 5 hours through 620 ℃.Can see, annealed after, the coercive force of magnet has reached 19.02kOe, squareness increases to some extent, this micro-structural that shows magnet is taken on a new look to some extent.Can see, by in Nd-Fe-B, adding Cr, use the method for sintering, can make magnetic energy product between 10～30MGOe, have a bigger coercitive Nd-Fe-Cr-B magnet.Fig. 2 b provides, adopts the demagnetization curve of the magnet that the method that reduces the degree of orientation obtains by application vendor, and the magnetic property of the magnet among this magnet and Fig. 2 a is suitable.Can find that by comparing the present invention adopts the magnet of the method acquisition of adding Cr, obviously be better than the magnet that prior art adopts the method acquisition that reduces the degree of orientation.
Fig. 3 a is the back scattering SEM figure of sintered Nd-Fe-Cr-B magnet when Cr content is 2.2wt.% among the embodiment 1, and Fig. 3 b is principal phase energy spectrum analysis (EDX) result of this Nd-Fe-Cr-B magnet, and Fig. 3 c is the EDX result of rich Nd phase.As can be seen, some enters into principal phase antiferromagnetism transition element Cr, some be present in rich Nd mutually in.The antiferromagnetism transition element Cr that enters into principal phase has just reduced the remanent magnetism and the magnetic energy product of magnet, and the Cr that enters into rich Nd phase has changed the micro-structural of magnet, and this is the main cause that coercive force increases.
Fig. 4 is Cr content that embodiment 1 the obtains alternating temperature demagnetization curve through the Nd-Fe-Cr-B of annealing in process magnet when being 1.5wt.%.Can see that in 100 ℃, the temperature coefficient of magnet remanent magnetism is approximately-0.08%/K, coercitive temperature coefficient is approximately-0.7%/K, has certain temperature stability.Therefore, if serviceability temperature is no more than 100 ℃, then this magnet should be able to provide the magnetic field of satisfying the demand.
Embodiment 2
Adopt the method for pairing gold, master alloying is that composition is R 14.5(Fe, TM) 79.5B 6(R=Nd, Pr, Dy, Tb; TM=Co, Cu, Al, Nb etc.) ingot casting, secondary alloy adopts the method for electric arc melting to obtain, its composition is R 14.5(Fe, TM, Mn) 79.5B 6(R=Nd, Pr, Dy, Tb; TM=Co, Cu, Al, Nb etc.).Putting into two stainless cylinder of steels respectively and carry out hydrogen fragmentation (HD), according to certain mixed powder, carry out airflow milling then after the hydrogen fragmentation, is orientation and moulding under the 2T in magnetic field, adds static pressure such as 200MPa, carries out sintering at last under vacuum state.Obtain coercive force H CjMore than or equal to 15kOe, remanent magnetism is less than 1.1T, and magnetic energy product is lower than the magnet of 30MGOe.
Embodiment 3
Adopt the method for single alloy, obtaining composition is R 14.5(Fe, TM, AF) 79.5B 6(R=Nd, Pr, Dy, Tb; TM=Co, Cu, Al, Nb; AF=Cr, Mn etc.) ingot casting.Putting into stainless cylinder of steel and carry out hydrogen fragmentation (HD), carry out airflow milling then, is orientation and moulding under the 2T in magnetic field, adds static pressure such as 200MPa, carries out sintering at last under vacuum state.Obtain the suitable magnet of magnetic property and embodiment 1.
Embodiment 4
Adopt the method for single alloy or pairing gold, composition is identical with embodiment 3.Concrete grammar and embodiment 2 are roughly the same, the difference part is that present embodiment does not adopt the hydrogen fragmentation, but powder in directly obtaining with Mechanical Crushing, carries out the method identical with embodiment 1 then, sintering temperature adjusts slightly, also can obtain and the suitable magnet of embodiment 2 performances.
Embodiment 5
Adopt single alloy or pairing gold method, composition is identical with embodiment 3.Adopt the method for ball milling to obtain fine powder, additive method is identical with embodiment 1, also can obtain and the suitable magnet of embodiment 2 magnetic properties.
The above sintered nd-fe-b magnet of making according to embodiments of the invention can adopt induction melting and electric arc melting to obtain ingot casting, and this ingot casting can be pie ingot casting or rapid hardening thin slice.By these methods, equal sintered nd-fe-b magnets that can obtain to meet the demands.
The detection of Nd-Fe-B magnet can detect by magnetic property, X-ray diffraction and scanning electron microscopy even light microscope.Antiferromagnetism such as Cr, Mn transition element can be determined by the method for chemical analysis, icp analysis and spectrum analysis.

Claims (3)

1, a kind of method of making sintered Nd-Fe-B magnet is characterized in that the method for this manufacturing sintered Nd-Fe-B magnet may further comprise the steps:
The preparation alloy cast ingot, wherein, this alloy cast ingot comprises antiferromagnetism transition element Cr or Mn;
This alloy cast ingot is ground into powder;
Be orientated this powder in the outside magnetic field, and its pressure is formed block pressed compact;
Sintering should the bulk pressed compact, and the heat treatment of annealing, and forms this sintered Nd-Fe-B magnet, and wherein, the magnetic parameter scope of this sintered Nd-Fe-B magnet is: remanent magnetism is smaller or equal to 1.1T, and magnetic energy product is 10～30MGOe, and coercive force is more than or equal to 15kOe,
Wherein, this sintered Nd-Fe-B magnet is made up of Nd, Fe, B and Cr, perhaps form by Nd, Fe, B and Mn,
Wherein, during the preparation alloy cast ingot, use low-purity metal element Cr or Mn, perhaps use Cr-Fe alloy or Mn-Fe alloy,
Wherein, in described low-purity metal element Cr or Mn, the purity of Cr or Mn is lower than 91at.%.
2, the method for manufacturing sintered Nd-Fe-B magnet according to claim 1 is characterized in that: in this sintered Nd-Fe-B magnet, the content of antiferromagnetism transition element Cr or Mn is 0.5～20at.%.
3, the sintered Nd-Fe-B magnet of a kind of method of manufacturing sintered Nd-Fe-B magnet according to claim 1 manufacturing.
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