CN105895286B - Rare earth element permanent magnet - Google Patents

Rare earth element permanent magnet Download PDF

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Publication number
CN105895286B
CN105895286B CN201610086719.0A CN201610086719A CN105895286B CN 105895286 B CN105895286 B CN 105895286B CN 201610086719 A CN201610086719 A CN 201610086719A CN 105895286 B CN105895286 B CN 105895286B
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rare earth
earth element
principal phase
permanent magnet
core portion
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CN105895286A (en
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大泽明弘
榎户靖
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TDK Corp
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TDK Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0572—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 with a protective layer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered

Abstract

Present invention offer is a kind of can to keep high coercitive R T B systems sintered magnet compared with prior art.The present invention provides a kind of rare earth element permanent magnet, it is characterized in that, the rare earth element permanent magnet is made up of (wherein R T B systems, R must contain R1 and R2, R1 is at least one kind of in the rare earth element for including Y and not including Dy, Tb, Ho, R2 be Dy, Tb, Ho in it is at least one kind of) sintered body form, with the principal phase particle comprising core portion and the core shell structure in the shell portion for coating the core portion, R1, the R2 in above-mentioned core portion atomic concentration are being designated as α R1, α R2 respectively, when R1, the R2 in above-mentioned shell portion atomic concentration are designated as into β R1, β R2 respectively, α R1<βR1、αR2>βR2、αR1<αR2、βR2<β R1, relative to the whole principal phase particles observed on the section of above-mentioned sintered body, it is more than 5% to have the ratio shared by the principal phase particle of above-mentioned core shell structure.

Description

Rare earth element permanent magnet
Technical field
The present invention relates to a kind of rare earth element permanent magnet, uses weight dilute in R-T-B systems sintered magnet more particularly to one kind The rare earth element permanent magnet for a part of R that earth elements have been replaced.
Background technology
It is known with tetragonal R2T14B compounds be principal phase R-T-B systems sintered magnet (R is rare earth element, T be Fe or The Fe that one part is substituted by Co, B are boron) there is excellent magnetic characteristic, it has been generation since the invention (patent document 1) of nineteen eighty-two The high performance permanent magnet of table.
The R-T-B systems sintered magnet anisotropy field Ha that rare-earth element R is made up of Nd, Pr, Dy, Tb, Ho preferably makees greatly For permanent magnet material.Wherein, saturated magnetization Is, the Curie temperature for the Nd-Fe-B systems permanent magnet that rare-earth element R is Nd are made Tc, anisotropy field Ha balance are excellent, than having used the R- of other rare-earth element Rs in terms of stock number, corrosion resistance T-B systems sintered magnet is more excellent, therefore, is widely used for the people's livelihood, industry, transporting equipment etc..
For existing R-T-B systems sintered magnet wish improve magnetic characteristic, particularly it is more try improve residual flux it is close Spend Br and coercivity H J.As one of them, have and usually improve coercive by adding such as high member of Dy or Tb magnetic anisotropy The method of power.
However, from the viewpoint of saving resource, cutting down cost, there is also arrive the heavy rare earth element amount control of addition Minimal requirement.As the method for addition heavy rare earth element, such as disclose technology (the patent text using grain boundary decision method Offer 2).
As other adding methods, disclosing progress RH-T phases (RH is heavy rare earth element), (RL is light with RL-T-B phases Rare earth element) mixing or the mixing of RH-T-B phases and RL-T-B phases make the technology of sintered body (patent document 3).
Prior art literature
Patent document
Patent document 1：Japanese Unexamined Patent Application 59-46008 publications
Patent document 2：No. 4831074 publications of Japanese Patent No.
Patent document 3：No. 4645855 publications of Japanese Patent No.
The content of the invention
The technical problems to be solved by the invention
However, the purposes of rare earth element magnet is related to many aspects in recent years, seek higher magnetic characteristic compared with existing.It is special It is not, when R-T-B systems sintered magnet is used in hybrid vehicle etc., because magnet is exposed at higher temperature, because This, it is more important to suppress the high temperature demagnetization as caused by heat.For suppressing high temperature demagnetization, it is necessary to improve R-T-B systems sintered magnet Coercivity at room temperature.
The present invention is to recognize that such situation and completed that, for R-T-B based sintered magnets, its object is to provide one Kind can more keep high coercitive permanent magnet compared with prior art.
Solve the means of technical problem
In order to solve the above-mentioned technical problem and reached purpose, rare earth element permanent magnet of the invention are characterised by, the rare earth Class permanent magnet is made up of that (wherein, R must contain R1 and R2, R1 be the rare earth for including Y and not including Dy, Tb, Ho R-T-B systems It is at least one kind of in element, at least one kind of in R2 Dy, Tb, Ho) sintered body form, have and include core portion and coat the core portion Shell portion core shell structure principal phase particle, R1, the R2 in above-mentioned core portion atomic concentration are being designated as α R1, α R2 respectively, will be upper When stating R1, the R2 in shell portion atomic concentration and being designated as β R1, β R2 respectively, α R1<βR1、αR2>βR2、αR1<αR2、βR2<β R1, relatively In the whole principal phase particles observed on the section of above-mentioned sintered body, there is the ratio shared by the principal phase particle of above-mentioned core shell structure For more than 5%.
In the present invention, the unit section for sintering body section is the region of 50 μm of square.
In R2T14In B crystal grain (principal phase particle), the heavy rare earth element concentration compared to outer edge has to more than 3at%'s is dense The part at degree difference and the center comprising principal phase particle is defined as core portion, will be defined as shell beyond the above-mentioned core portion of principal phase particle Portion, the principal phase particle with above-mentioned core portion and shell portion is referred to as nucleocapsid particles.By from principal phase particle surface to 0.5 μm of depth Outer edge is defined as, outer edge is contained in shell portion.
Whether the present inventors can play heavy rare earth element to greatest extent and had to having in R-T-B systems sintered magnet The structure of high-coercive force effect specialized in.Its result is found, by making R-T-B systems sintered magnet contain with upper The principal phase particle of core shell structure is stated, so as to obtain high-coercive force.Its reason is indefinite, but the present inventors speculate such as Under.First, it is believed that the effect is as caused by the pinning effect of caused magnetic wall on the interface in core portion and shell portion.Although core Portion and shell portion have identical R2Fe14B structure, but because the ratio of heavy rare earth element in the R species in core portion is more deposited , and the ratio of LREE is more present in the R species in shell portion, and therefore, both lattice constants are different.Thus exist The interface in core portion and shell portion deforms.Think that this is deformed into pinning site, play the effect for the movement for hindering magnetic wall.Its It is secondary, it is believed that the effect be as by add heavy rare earth element and the raising effect of caused anisotropy field caused by.Again It is secondary, it is believed that the effect is by with the few RL of lattice defect2T14B principal phases (RL is the LREE for including Y) coat lattice defect More RH2T14Caused by B principal phases (RH is heavy rare earth element) and caused effect.If lattice be present in principal phase particle surface The defects of defect, then it turns into magnetization inversion core generation site, and causes coercitive reduction.Therefore, if the quantity of defect More, then corresponding coercivity can substantially reduce.Because heavy rare earth element is the element that is easily widely spread in Grain-Boundary Phase, and RH2T14B principal phases and RL2T14B principal phases are lower compared to the stability of energy, therefore, RH2T14B principal phases can easily produce lattice and lack Fall into.Therefore, by using the few RL of lattice defect2T14B principal phases coat RH2T14B principal phases, so as to prevent from being led by lattice defect The coercitive reduction caused.In addition, the ratio for passing through the principal phase granule number with above-mentioned core shell structure is more than 5%, can obtain The effect increased substantially to coercivity.
As the preferred embodiment of the present invention, the R2 contained by sintered body is preferably below 11at%.
Concentration by heavy rare earth element in the R-T-B systems sintered magnet of the present invention is below 11at%, so as to press down The significantly reduction of residual magnetic flux density processed.The reason for by the addition of heavy rare earth element reduce residual magnetic flux density, recognizes To be due to that the magnetic moment of heavy rare earth element is coupled so as to cause magnetized reduction with Nd or Fe magnetic moment antiparallel.The present invention is Based on the discovery that and complete.
The effect of invention
As described above, according to the present invention it is possible to R-T-B systems sintered magnet is set to have than existing higher coercivity.
Embodiment
Hereinafter, the present invention is explained based on embodiment.In addition, the present invention is not by following embodiment and reality The content described in example is applied to limit.In addition, the inscape in following described embodiment and embodiment includes this area The content of impartial scope that technical staff can be readily apparent that, substantially the same, so-called.Further, it is described below Inscape disclosed in embodiment and embodiment can also be selected suitably to use with appropriately combined.
R-T-B systems sintered magnet involved by present embodiment contains 11~18at% rare earth element (R).If R's Concentration is less than 11at%, then as R-T-B systems sintered magnet principal phase R2T14The generation of B phases is insufficient, has soft magnetism α-Fe etc. are separated out, and coercivity significantly reduces.On the other hand, if R is more than 18at%, the R as principal phase2T14B phases Volume ratio reduces, so as to which residual magnetic flux density reduces.In addition, R reacts with oxygen, the oxygen amount increase contained, it is accompanied by this to rectifying The effective R enrichment phases of generation of stupid power are reduced, and cause coercitive reduction.
In the present embodiment, above-mentioned rare earth element (R) includes R1, R2.R1 be include Y and not include Dy, Tb, Ho it is dilute It is at least one kind of in earth elements, it is at least one kind of in R2 Dy, Tb, Ho.Preferably with respect to total rare earth concentration (TRE), R1/ TRE is the ratio that 30~92 weight %, R2/TRE are 8~70 weight %.Here, as R, raw material can also be come from containing being used as Impurity or during manufacture mixed impurity other compositions.
R-T-B systems sintered magnet involved by present embodiment contains 5~8at% boron (B).It is less than 5at% feelings in B Under condition, it is impossible to obtain high coercivity.On the other hand, if B ultrasound crosses 8at%, there is residual magnetic flux density reduction.Cause This, is set as 8at% by the B upper limit.
R-T-B systems sintered magnet involved by present embodiment contains 74~83at% transition metal T, the present invention In T using Fe as indispensable element, wherein can the Co containing below 4.0at%.Co formation and Fe identical phases, but carrying High-curie temperature, the corrosion resistance aspect of raising Grain-Boundary Phase are effective.In addition, the R-T-B systems sintered magnet that the present invention is applicable can 1 kind or 2 kinds that Al and Cu is contained with the scope with 0.01~1.2at%.By contain Al and Cu with the scope a kind or 2 kinds, Obtained from sintered magnet can high-coercive force, highly corrosion resistant, and temperature characterisitic can be improved.
R-T-B systems sintered magnet involved by present embodiment is allowed containing other elements.For example, can suitably it contain The elements such as Zr, Ti, Bi, Sn, Ga, Nb, Ta, Si, V, Ag, Ge.On the other hand, the impurity such as oxygen, nitrogen, carbon member is preferably reduced as far as possible Element.The oxygen of particularly harmful magnetic characteristic, is preferably set as below 5000ppm by its amount, be further preferably set as 3000ppm with Under.If oxygen amount is more, the rare-earth oxide as non-magnetic constituents mutually increases, and reduces magnetic characteristic.
R-T-B systems sintered magnet involved by present embodiment, except the R as principal phase particle2T14Outside B crystal grain, also The complex tissue that equal eutectic composition is formed is enriched with the R enrichment phases by being referred to as Grain-Boundary Phase, B.The size of principal phase particle For 1~10 μm or so.
Hereinafter, the preferred example of the manufacture method of this part invention is illustrated.
In the manufacture of the R-T-B systems sintered magnet of present embodiment, first, prepare raw alloy respectively to be had The R1-T-B based magnets and R2-T-B based magnets of desired composition.Raw alloy can in vacuum or inert gas, be preferably Made in Ar atmosphere by thin strap continuous casting method, other well known fusion method.Thin strap continuous casting method is in Ar by feed metal Melted in the nonoxidizing atmospheres such as gas atmosphere, thus obtained molten metal is ejected to the surface of the roller of rotation.By roller chilling Molten metal afterwards is frozen into thin plate or thin slice (scale) shape by chilling.It is 1 that alloy after chilling solidification, which has crystallization particle diameter, The tissue of~50 μm of homogeneous.Raw alloy is not limited to be obtained by thin strap continuous casting method, can melt method by high-frequency induction melting etc. To obtain.In addition, in order to prevent the segregation after melting, such as water-cooled copper plate can be poured into be allowed to solidify.Furthermore it is possible to make Alloy by the use of obtained by by reduction-diffusion process is used as raw alloy.
The raw alloy of obtained R1-T-B systems and R2-T-B systems is mixed, there is provided to pulverizing process.The blending ratio root According to the appropriate adjustment such as mixed target composition.It is preferred that the weight of R1-T-B alloys is than the weight for 30~92%, R2-T-B alloys Amount is than being 8~70%.Pulverizing process has coarse crushing process and Crushing of Ultrafine process.First, raw alloy coarse powder is broken to particle diameter number Hundred μm of degree.Coarse crushing is preferably ground using stamping mill (stamp mill), jaw crusher (jaw crusher), Blang (Braun mill) etc., is carried out in inert gas atmosphere.Before coarse crushing, make it after being adsorbed in raw alloy by making hydrogen Release is come to carry out crushing be effective.It is to turn into the hydrogen as the impurity of rare-earth sintered magnet as mesh to reduce that processing is put in hydrogen release Come carry out.The temperature that heating for hydrogen absorption is kept is set as more than 200 DEG C, is preferably set to more than 350 DEG C.Keep Time changes according to the relation with keeping temperature, thickness of raw alloy etc., is at least set as more than 30 minutes, preferably sets For more than 1 hour.Hydrogen release is put processing and carried out in a vacuum or in Ar air-flows.In addition, hydrogen adsorption treatment, hydrogen release put processing not must The processing of palpus.The hydrogen can also be crushed and be positioned as coarse crushing, so as to omit the coarse crushing of machinery.
After coarse crushing process, above-mentioned alloy is transferred to Crushing of Ultrafine process.Mainly airflow milling (jet is used in Crushing of Ultrafine Mill), average grain diameter is made as 2.5~6 μm, preferably 3~5 μm in the coarse powder comminuted powder of hundreds of μm of degree of particle diameter.Airflow milling is The air-flow of high speed is produced by the inert gas of narrow and small nozzle release high pressure, coarse crushing is accelerated by the air-flow of the high speed Powder, produce the mutual collision of coarse powder comminuted powder or the method collided to be crushed with target or chamber wall.
Case of wet attrition can also be used in Crushing of Ultrafine., will using ball mill or wet grinding machine etc. in case of wet attrition Average grain diameter is made as 1.5~5 μm, preferably 2~4.5 μm in the coarse powder comminuted powder of hundreds of μm of degree of particle diameter.Due in wet type powder By selecting appropriate decentralized medium in broken, so as to be crushed under conditions of magnetic iron powder does not contact with oxygen, therefore can obtain The micropowder low to oxygen concentration.
Can add in Crushing of Ultrafine 0.01~0.3wt% or so to be molded when lubrication and orientation rise to mesh Aliphatic acid or aliphatic acid derivative or hydrocarbon, such as be used as the zinc stearate of stearic acid system or oleic acid system, calcium stearate, hard Resin acid aluminium, stearic amide, oleamide, ethylenebis isostearic acid acid amides；Paraffin, naphthalene as hydrocarbon etc..
Above-mentioned micro mist is supplied in magnetic field and is molded.The briquetting pressure being molded in magnetic field can be set as 0.3~3ton/ cm2(30~300MPa) scope.Briquetting pressure can since shaping start to end be it is certain, can also be cumulative or decrescence, or Can irregularly it change.The more low then orientation of briquetting pressure is better, but if briquetting pressure is too low, then the intensity of formed body is not Problem can be produced in processing enough, therefore briquetting pressure is selected from above range in view of this point.By being molded institute in magnetic field The final relative density of obtained formed body is usually 40~60%.
The magnetic field applied can be set as 10~20kOe (960~1600kA/m) left and right.The magnetic field applied does not limit In magnetostatic field, or the magnetic field of pulse type.Alternatively, it is also possible to and with magnetostatic field and pulse type magnetic field.
Then, the sintered moulded body in vacuum or inert gas atmosphere.Sintering temperature is necessary according to composition, crushing side All conditions such as the difference of method, average grain diameter and size distribution are adjusted, and are sintered in the present invention at 850~950 DEG C.At this LREE easily spreads under sintering temperature, and heavy rare earth element is difficult to spread.Thus only LREE widely expands Dissipate, in R22T14LREE denseization in the outer edge of B principal phases (at least one kind of in R2 Dy, Tb, Ho), can obtain and wish The structure of prestige.If sintering temperature is more than 1000 DEG C, both LREE, heavy rare earth element widely spread, from And desired structure can not be obtained.In addition, if being the temperature less than 850 DEG C, then temperature is not enough to spread, it is impossible to obtains institute Desired structure.
Sintering time is necessary to be entered according to all conditions such as the difference of composition, breaking method, average grain diameter and size distribution Row adjustment, is set as 48~96 hours.Because above-mentioned sintering temperature is low temperature, therefore, in order to obtain sufficient sintered density and Sintering time is necessary for more than 48 hours.In addition, if more than 96 hours, then principal phase grain grows, so as to which coercivity is big Amplitude reduction.The principal phase particle of sintered body is preferably sized to less than 10 μm.
After sintering, Ageing Treatment can be implemented to obtained sintered body.The process is the coercitive important process of control. In the case where Ageing Treatment to be divided into the progress of 2 stages, it is effective that the stipulated time nearby, near 600 DEG C is kept at 800 DEG C. If carrying out the heat treatment near 800 DEG C after sintering, coercivity increase, therefore it is especially effective in mixing method.In addition, by Coercivity greatly increases in the heat treatment near 600 DEG C, therefore in the case where carrying out Ageing Treatment with 1 stage, can To implement the Ageing Treatment near 600 DEG C.
Embodiment
Hereinafter, explain present disclosure using embodiment and comparative example, but the present invention be not limited to Under embodiment.
(embodiment 1~3)
In order to make R1-T-B systems alloy and R2-T-B systems alloy respectively, with the metal or raw alloy for synthesizing raw material with As composition as shown in table 1, melted respectively by thin strap continuous casting method, cast raw material latten.R2 species is Dy, Tb, Ho It is any, respectively as embodiment 1, embodiment 2, embodiment 3.
By obtain 2 kinds of raw alloy thin plates with 92:8 weight carries out hydrogen crushing than mixing, obtains coarse powder comminuted powder. 0.1wt% oleamide is added in the coarse powder comminuted powder respectively as lubricant.Then, using jet mill (air-flow Mill), carry out Crushing of Ultrafine respectively in high pressure nitrogen atmosphere, obtain micro mist comminuted powder.
Then, obtained micro mist comminuted powder is put into mould, be molded in magnetic field.Specifically, in 15kOe magnetic It is molded in 140MPa pressure, obtains 20mm × 18mm × 13mm formed body.Magnetic direction is and pressing direction Vertical direction.Resulting formed body is sintered 48 hours at 850 DEG C.Thereafter, the timeliness of 1 hour is carried out at 600 DEG C Processing, so as to obtain sintered body.
For obtained sintered body, residual magnetic flux density (Br) and coercivity are determined using BH tracing instruments (BH tracer) (HcJ).Its result is as shown in table 3.
After resulting sintered body is abreast cut off relative to easy magnetized axis, its resin is filled to epoxy tree In fat, its section is ground.Using commercially available sand paper during grinding, while shifting to high sand paper on one side from the low sand paper of granularity It is ground.Finally it is ground using polishing wheel (buff) and diamond abrasive grain.Now, it is ground without water etc..If Using water, then crystal boundary phase constituent can corrode.
Ion milling is carried out to obtained sintering body section, eliminate oxide-film or the nitride film of most surface etc. influence it Afterwards, with EPMA (electron probe microanalyzers：Electron Probe Micro Analyzer) observation R-T-B systems sintering magnetic The section of iron, and analyzed.Using the region of 50 μm of square as unit section, survey and draw by EPMA element (element mapping) (256 points × 256 points).Here, the observation position in section is optional position.Thus principal phase is judged Particle and crystal boundary, for the whole principal phase particles being able to confirm that in unit cross-sectional area, try to achieve and whether there is core shell structure, each core portion With the composition in shell portion.
It is as described below for the details of the analysis method of principal phase particle.
(1) using the specific principal phase particle of image analytical method according to the backscattered electron image observed in unit section Part and grain boundary portion.
(2) concentration of element is calculated according to the surveying and mapping data of R1, R2 for being obtained with EPMA characteristic X-ray intensity, will be with master The heavy rare earth element concentration of the outer edge of phase particle is compared to the setting of the region at concentration high more than 3% and the center comprising principal phase particle For core portion, the position beyond above-mentioned core portion is set as shell portion.For 1 visual field, whole granule numbers (D), nucleocapsid particles are investigated Number (E), calculate the ratio (E/D) of nucleocapsid particles number.
(3) operation of above-mentioned (1) and (2) is carried out in 20 visuals field in the section of same sample, calculates nucleocapsid particles The average value (α R1, α R2) of terres rares concentration in core portion, nucleocapsid particles shell portion terres rares concentration average value (β R1, β R2).Then, the average value of the ratio of the nucleocapsid particles number in every 1 visual field is tried to achieve.
(comparative example 1)
In order to manufacture R1-T-B systems alloy, coordinate metal or raw alloy as raw material with as group as shown in table 2 Into, pass through thin strap continuous casting method melt, cast raw material latten.
[table 2]
Obtained raw alloy thin plate hydrogen is crushed, obtains coarse powder comminuted powder.0.1wt% is added in the coarse powder comminuted powder Oleamide as lubricant.Then, using jet mill (airflow milling), micro mist is carried out in high pressure nitrogen atmosphere It is broken, obtain micro mist comminuted powder.
Then, obtained R1-T-B series alloy powders are put into mould, be molded in magnetic field.Specifically, exist It is molded in 15kOe magnetic field with 140MPa pressure, obtains 20mm × 18mm × 13mm formed body.Magnetic direction be with The vertical direction of pressing direction.Resulting formed body is sintered 12 hours at 1050 DEG C.Thereafter, it is small that 1 is carried out at 600 DEG C When Ageing Treatment, obtain sintered body.
For obtained sintered body, Br, HcJ are determined using BH tracing instruments similarly to Example 1.It the results are shown in table In 3.
[table 3]
In embodiment 1~3, the core portion for having heavy rare earth element R2 atomic concentration high and LREE R1 be present The high shell portion of atomic concentration core shell structure principal phase particle.Moreover, its coercivity is than no addition heavy rare earth element The higher value of Nd-Fe-B comparative example 1.As described above, this is considered as due to the addition by heavy rare earth element and core shell structure Effect caused by anisotropy field raising and as caused by deformation pinning effect, lattice defect influence relax caused by 's.
(embodiment 4~7)
In addition to additional Pr or Y, Ce, La etc. in LREE R1 species, raw material is carried out similarly to Example 1 Making, crushing, shaping, sintering, the evaluation of latten.Detailed composition is recorded in table 4, evaluation result is recorded in table In 5.
In embodiment 4~7, exist with the core portion that more heavy rare earth element be present and more LREE be present The principal phase particle in shell portion, and high coercivity can be obtained.From the above, it was confirmed that imported in R1 light beyond Nd Rare earth element, core shell structure and high-coercive force can also be obtained similarly to Example 1.
(comparative example 2)
In order to make R1-T-B systems alloy and R2-T systems alloy respectively, coordinate as raw material metal or raw alloy with into For composition as shown in table 6, melted respectively by thin strap continuous casting method, cast raw material latten.Thereafter, by R1-T-B systems alloy With R2-T systems alloy with weight ratio 93:7 mixing, are crushed, are molded, are sintered, are evaluated similarly to Example 1.
(comparative example 3)
In order to make R1-R2-T-B systems alloy, coordinate metal or raw alloy as raw material with as shown in table 6 Composition, melted by thin strap continuous casting method, cast raw material latten.Thereafter, crushed, be molded, burnt similarly to Example 1 Knot, evaluation.
[table 6]
[table 7]
In comparative example 2, it can produce by the core portion of more LREE be present and more heavy rare earth element be present The core shell structure that shell portion is formed.However, its coercivity is not as good as embodiment 1.In comparative example 3, confirm no core shell structure, turn into The coercivity lower than embodiment 1.
(comparative example 4~7, embodiment 8~9)
It is other to carry out the making of raw alloy thin plate, crushing, shaping, burning similarly to Example 1 in addition to sintering temperature Knot, evaluation.Sintering temperature is set to 750 DEG C, 800 DEG C, 900 DEG C, 950 DEG C, 1000 DEG C, 1050 DEG C, and respectively as comparative example 4th, comparative example 5, embodiment 8, embodiment 9, comparative example 6, comparative example 7.Show the result in table 8.
In embodiment 1 and embodiment 8~9, by the way that sintering temperature is set as into 850~950 DEG C, can be had More LREE R1 shell portion be present and the principal phase particle in more heavy rare earth element R2 core portion be present.Its coercivity can be with Obtain 4, the 5 higher value of comparative example than no core shell structure.The reason for thinking that core shell structure can not be formed in comparative example 4,5 It is due to that sintering temperature is too low, so as to which R1 elements are difficult to spread.Can not at a temperature of higher than 950 DEG C as comparative example 6~7 Core shell structure is produced, so as to coercivity step-down.It is due to that sintering temperature is high temperature to think the reason for it can not produce core shell structure, So as to which R1 is widely diffused in sintered body entirety.
(comparative example 8~11, embodiment 10~12)
It is other to carry out the making of raw alloy thin plate, crushing, shaping, burning similarly to Example 1 in addition to sintering time Knot, evaluation.Sintering time is set as 24 hours, 36 hours, 72 hours, 84 hours, 96 hours, 108 hours, 120 hours, and Respectively as comparative example 8, comparative example 9, embodiment 10, embodiment 11, embodiment 12, comparative example 10, comparative example 11.Result is shown In table 9.
In embodiment 10~12, core shell structure same as Example 1 be present, and high-coercive force can be obtained. It is the low result of coercivity in the absence of core shell structure in comparative example 8,9.This be considered as because sintering time is short, from without Fully cause R1 diffusion.In addition, residual magnetic flux density is also low value.This be considered as because not only sintering temperature is low, And sintering time is short, so as to which sufficient sintered density can not be obtained.
It is the low result of coercivity although comparative example 10,11 can obtain core shell structure similarly to Example 1. This is considered as because sintering time is grown, and so as to which principal phase grain grows, is accompanied by this coercivity reduction.
(comparative example 12~15, embodiment 13~16)
R1-T-B system's alloys and R2-T-B systems alloy are made similarly to Example 1.Thereafter, 98 are turned into weight ratio:2、 95:5、92:8、70:30、50:50、30:70、20:80、10:90 mode is mixed, and is carried out into similarly to Example 1 Type, sintering, evaluation.Mixed composition is shown in Table 10.
Then, Br, HcJ are determined using BH tracing instruments similarly to Example 1.Then, enter row element by EPMA to survey and draw, Total and nucleocapsid particles number the measure of progress principal phase particle,
The rare earth element concentration α R1 in shell portion of core portion, α R2, β R1, β R2 measure.Its result is as shown in table 11.
[table 11]
Comparative example 12~13, embodiment 13~18 all contain with by the core portion more than heavy rare earth element, light rare earth member The principal phase particle for the structure that shell portion more than element is formed.In addition, according to embodiment 13~16, the ratio of nucleocapsid particles number for 5% with On, when R2 concentration is below 11at%, keeps high residual magnetic flux density and high-coercive force can be obtained.In nucleocapsid particles number Ratio less than 5% comparative example 12~13 in, be low-coercivity.This is considered because the addition of heavy rare earth element is few, companion Also lack with this nucleocapsid particles quantity, therefore, coercitive raising effect is insufficient.Exceed 11at% embodiment in R2 concentration Although can obtain high-coercive force in 17~18, residual magnetic flux density substantially reduces.This is considered due to heavy rare earth element Addition caused by saturated magnetization reduce.
(embodiment 19~20)
In order to make R1-T-B systems alloy and R1-R2-T-B systems alloy, coordinate as raw material metal or raw alloy with As composition as shown in table 12, melted respectively by thin strap continuous casting method, cast raw material latten.Thereafter, it is same with embodiment 1 Crushed sample, be molded, sintered, evaluated.Show the result in table 13.
[table 13]
In embodiment 19,20, the content for obtaining core portion more than the content by heavy rare earth element and LREE is more Shell portion form core shell structure, high-coercive force can be obtained compared with comparative example 1.Compared with Example 1, even if can confirm that In the case that the composition of R1 and R2 in core portion compare there occurs change, high-coercive force can also be obtained.
The possibility utilized in industry
As described above, R-T-B systems sintered magnet involved in the present invention keeps high residual magnetic flux density and also had High coercivity, it is suitable as requiring the permanent magnetic used in height output or efficient people's livelihood industrial handling equipment etc. Iron.

Claims (2)

  1. A kind of 1. rare earth element permanent magnet, it is characterised in that
    The sintered body that the rare earth element permanent magnet is made up of R-T-B systems is formed, wherein, it is to include that R, which must contain R1 and R2, R1, It is at least one kind of in Y and the not rare earth element including Dy, Tb, Ho, it is at least one kind of in R2 Dy, Tb, Ho,
    The rare earth element permanent magnet has the principal phase particle of the core shell structure comprising core portion and the shell portion for coating the core portion,
    The core portion has more than 3at% concentration difference and comprising principal phase particle for the heavy rare earth element concentration compared to outer edge Center part, the shell portion for principal phase particle the core portion beyond part,
    R1, the R2 in the core portion atomic concentration are being designated as α R1, α R2 respectively, by R1, the R2 in the shell portion atomic concentration When being designated as β R1, β R2 respectively, α R1<βR1、αR2>βR2、αR1<αR2、βR2<β R1,
    Relative to the whole principal phase particles observed on the section of the sintered body, the principal phase particle institute with the core shell structure The ratio accounted for is more than 5%.
  2. 2. rare earth element permanent magnet as claimed in claim 1, it is characterised in that
    R2 contained by the sintered body is below 11at%.
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