CN1958824B - R-T-B type alloy, production method of r-t-b type alloy flake, permanent magnet, and fine powder for manufacturing the same - Google Patents

R-T-B type alloy, production method of r-t-b type alloy flake, permanent magnet, and fine powder for manufacturing the same Download PDF

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CN1958824B
CN1958824B CN2006101431062A CN200610143106A CN1958824B CN 1958824 B CN1958824 B CN 1958824B CN 2006101431062 A CN2006101431062 A CN 2006101431062A CN 200610143106 A CN200610143106 A CN 200610143106A CN 1958824 B CN1958824 B CN 1958824B
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alloy
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slice
rare earth
temperature
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CN1958824A (en
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佐佐木史郎
长谷川宽
中岛健一朗
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TDK Corp
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Showa Denko KK
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
    • B22D11/0611—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by a single casting wheel, e.g. for casting amorphous metal strips or wires
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/10—Ferrous alloys, e.g. steel alloys containing cobalt
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • B22F2009/044—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling by jet milling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B22F2998/10—Processes characterised by the sequence of their steps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H01F41/0273—Imparting anisotropy

Abstract

The present invention provides an R-T-B type alloy as a raw material of a rare earth-based permanent magnet having excellent magnetic characteristics. The present invention provides an R-T-B type alloy (wherein R is at least one member selected from rare earth elements including Y, T is a transition metal essentially comprising Fe, and B is boron) which is a raw material for use in a rare earth-based permanent magnet, wherein the volume percentage of the region containing an R 2 T 17 phase having an average grain diameter of 3 Micron or less in the short axis direction is from 0.5 to 10%.

Description

R-T-B is alloy, its alloy slice manufacture method and permanent magnet and fine powder for manufacturing thereof
Technical field
The present invention relates to a kind of R-T-B is that alloy, R-T-B are the manufacture method of alloy slice, the fine powder that is used for R-T-B based rare earth permanent magnet (magnet) and R-T-B based rare earth permanent magnet.The invention particularly relates to a kind of R-T-B by Strip casting (strip casting) method manufacturing is alloy slice.
Background technology
The R-T-B series magnet that has maximum magnetic energy product in permanent magnet is owing to its high performance feature is used for HD (hard disk), MRI (nuclear magnetic resonance) and various motors etc.Along with in recent years except the thermotolerance of R-T-B series magnet to the increase of energy-conservation demand, comprise that automobile rises to the rate of utilization of motor.
The R-T-B series magnet comprises Nd, Fe and the B as main component, and therefore this magnet jointly is called Nd-Fe-B system or R-T-B series magnet.In the R-T-B series magnet, R mainly is the Nd that has by such as the displaced part of other rare earth element of Pr, Dy and Tb, and is at least a composition of selecting from the rare earth element that comprises Y; T is the Fe that has by such as the displaced part of transition metal of Co and Ni; B is boron and can be partly replaced by C or N.Equally, in the R-T-B series magnet, the combination of one or more that select from Cu, Al, Ti, V, Cr, Ga, Mn, Nb, Ta, Mo, W, Ca, Sn, Zr, Hf etc. can be used as to be added element and adds.
The R-T-B that makes the R-T-B series magnet is that alloy is the ferromagnetism R that helps magnetization 2T 14B be mutually principal phase and with the alloy that coexists mutually with low-melting rich R (R-rich) of nonmagnetic, concentrated rare earth element.This alloy is a reactive metal, and therefore usually in a vacuum or fusing or casting in the rare gas element.Usually be that alloy pig is made sintered magnet by following powder metallurgical technique from the R-T-B that casts.Alloy pig is ground into is about 3 μ m (when by FSSS (Fishersub-sieve sizer, when Fischer subsieve sizer) measuring) powdered alloy, extrusion molding in magnetic field, in sintering oven, be about sintering under 1000 to 1100 ℃ the high temperature, then if desired then through Overheating Treatment and machining, and electroplate to strengthen erosion resistance, finish sintered magnet thus.
In the R-T-B based sintered magnet, rich R plays following vital role mutually:
1) when sintering, becomes liquid phase owing to low-melting advantage, and therefore help the high compactionization (densification) of magnet, and strengthen the specific magnetising moment then;
2) eliminate the unevenness on crystal boundary (grain circle), and therefore in the nucleation site of reverse domain (contrary magnetic domain), produce decay and increase coercive force (coercive force, coercive force); And
3) magnetically isolate principal phase, and increase coercive force thus.
Therefore, if the rich R in the shaping magnet is under the poor dispersion state mutually, then cause the bad or magnetic decay of local sintering.Therefore, rich R is disperseed equably in the shaping magnet.Here, the distribution of rich R phase is subjected to the very big influence that raw material R-T-B is an alloy structure.
R-T-B is that another problem that runs in the alloy is the generation of α-Fe in casting alloy in casting.α-Fe has deformability and stays in the pulverizer and do not pulverized, and this crush efficiency when not only reducing alloy and pulverizing, and influence composition and fluctuate or size-grade distribution.If α-Fe still stays in the magnet behind sintering, then can cause the decay of the magnetic characteristic of magnet.Therefore, α-Fe is used as the material processing that should eliminate from raw alloy as much as possible.For this purpose, alloy is handled to eliminate α-Fe through at high temperature homogenizing for a long time at present.When the amount of α-Fe in the raw alloy is very little, can handles by homogenizing and eliminate α-Fe.Yet α-Fe exists as peritectoid nuclear, so its elimination needs long solid phase diffusion.Ingot have the thickness of several cm and content of rare earth be 33% or lower situation under, the elimination of α-Fe is in fact impossible.
In order to solve at R-T-B is the problem that generates α-Fe in the alloy, developed the Strip casting method (abbreviating the SC method as) of casting alloy ingot under higher rate of cooling, and this method is used in the actual process.
This SC method is the method by quick cooled and solidified alloy, and wherein melted alloy casts on the copper roller of inner water-cooled, and produces 0.1 to 1mm thin slice.In this SC method, the melted alloy undercooling is to generating main R 2T 14The temperature of B phase is so that directly generate R from melted alloy 2T 14B mutually and can suppress separating out of α-Fe.And in this SC method, alloy becomes and has fine crystal structure, so that can make the alloy with the fine dispersive tissue that allows rich R phase.Rich R is by expanding with H-H reaction in nitrogen atmosphere, and becomes the hydride of frangible (crisp).By utilizing this specific character, can introduce the fine-powdered that matches with rich R dispersity mutually.When alloy is pulverized by this step of hydrogenation, cause breaking of alloy by a large amount of crack that hydrogenization produces, and therefore obtain extraordinary degree of grinding.Therefore the rich R in inside in the alloy of making by this SC method disperses mutually imperceptibly, and this also bring pulverize with sintering after in magnet rich R good dispersiveness mutually, and successfully strengthened the magnetic characteristic (for example, seeing patent documentation 1) of magnet thus.
Alloy slice by this SC method manufacturing organize on the uniformity also very good.Can relatively organize uniformity by the dispersion state of crystal grain diameter or rich R phase.Under the situation of the alloy slice of making by this SC method,, can obtain the suitable fine homogeneous structure that produces by quick cooled and solidified generally through the last chill crystal that produces of casting roll one side (hereinafter referred to as " mold face side ") of the alloy slice of being everlasting.
As mentioned above, at the R-T-B by this SC method manufacturing is in the alloy, rich R disperses and has also suppressed separating out of α-Fe mutually imperceptibly, so that in the manufacturing of sintered magnet, the uniformity of the rich R phase in the final magnet can be improved, and the disadvantageous effect of α-Fe can be avoided pulverizing and magnetic.By this way, the R-T-B by this SC method manufacturing is that alloy pig has the extraordinary tissue that is used to make sintered magnet.Yet along with the enhancing of magnetic properties, to the raw alloy tissue, the requirement of the senior control of the existence of especially rich R phase has improved.
It is alloy relation between the behavior (performance) during with hydrogen cracking or pulverizing that the inventor has studied R-T-B that casting makes in advance, and find in order to control the granularity of the powdered alloy that is used for sintered magnet, the control of the dispersion state of rich R phase is important (for example, seeing patent documentation 2).Equally, find that also the rich R that generates on the mold face side is easy to take place fine-powdered in dispersive zone (fine rich R region) mutually extremely imperceptibly in alloy, the result, the pulverizing stability of alloy worsens, and simultaneously, the size-grade distribution of powder enlarges.It is necessary for the enhancing of magnetic (body) characteristic that this discovery makes minimizing that the people understands rich R region.
[patent documentation 1] JP-A-5-222488 (term of Shi Yonging " JP-A " means " not examining disclosed Japanese patent application " herein)
[patent documentation 2] JP-A-2003-188006
Summary of the invention
Yet,, also need further to strengthen magnetic properties even be in the alloy at patent documentation 2 disclosed R-T-B.
In these cases, make the present invention, and to the purpose of this invention is to provide a kind of R-T-B be alloy as the raw material rare earth class permanent magnet with good magnetic characteristics.
The inventor has especially observed the cross section tissue of the alloy slice of casting in all cases and solidifying, and finds to have a kind of relation between the precipitation state of 2-17 phase and magnetic properties, when separate out fine 2-17 phase (R in alloy 2T 17Phase) time, can strengthen magnetic properties.
Equally, the inventor has confirmed such fact, that is, and and when with allowing to exist fine R 2T 17The alloy of phase or by control in described SC method on the casting roll rate of cooling or the temperature when casting roll separates prepare alloy manufacturing sintered magnet the time, its coercive force stably increases, and obtains good magnetic properties.The present invention is based on these discoveries and realize.
That is, the invention provides following invention.
(1) a kind of R-T-B is an alloy, wherein R is at least a composition that is selected from the rare earth element that comprises Y, and T is the transition metal that must comprise Fe, and B is a boron, this alloy is the raw material that is used for the rare earth class permanent magnet, wherein is included in the R that has 3 μ m or littler median size on the short-axis direction 2T 17The volume percent in the zone of phase is from 0.5 to 10%.
(2) be alloy as (1) described R-T-B, wherein allow on short-axis direction, to have the R of 3 μ m or littler median size 2T 17The volume percent in the zone that coexists mutually with the rich R that has 3 μ m or littler median size on short-axis direction is from 0.5 to 10%.
(3) be alloy as (1) or (2) described R-T-B, wherein be included in the R that has 10 μ m or bigger median size on the short-axis direction 2T 17The volume percent in the zone of phase is 10% or littler.
(4) be alloy as each described R-T-B in (1) to (3), wherein be included in the R that has 5 μ m or bigger median size on the short-axis direction 2T 17The volume percent in the zone of phase is 10% or littler.
(5) be alloy as each described R-T-B in (1) to (4), wherein said R 2T 17Be non-equilibrium phase mutually.
(6) be alloy as each described R-T-B in (1) to (5), this alloy is 0.1 thin slice to the mean thickness of 1mm that has by the manufacturing of Strip casting method.
(7) a kind of is the method for alloy slice by Strip casting method manufacturing R-T-B, comprises and sets mean thickness for 0.1 to 1mm, and set melted alloy for every 1cm width 10g/sec or bigger to the average delivery rate of casting roll.
(8) be used to make the method that R-T-B is an alloy slice as (7) are described, wherein R-T-B is that the average rate of cooling of alloy on casting roll is from 500 to 3000 ℃/sec.
(9) be used to make the method that R-T-B is an alloy slice as (7) or (8) are described, wherein the R-T-B medial temperature that is alloy when casting roll separates is R under the equilibrium state of alloy than R-T-B 2T 14Low 100 to 400 ℃ of the temperature of solidification of B phase.
(10) R-T-B by the manufacture method manufacturing that is alloy slice of each described R-T-B in (7) to (9) is an alloy.
(11) be the fine powder that is used for R-T-B based rare earth permanent magnet of alloy manufacturing from each described R-T-B as (1) to (6) and (10).
(12) R-T-B based rare earth permanent magnet from making as (11) described fine powder that is used for R-T-B based rare earth permanent magnet.
At R-T-B of the present invention is in the alloy, is included in the R that has 3 μ m or littler median size on the short-axis direction 2T 17The volume percent in the zone of phase is from 0.5 to 10%, thereby can realize having the rare earth class permanent magnet of high-coercive force and good magnetic characteristics.
Equally, at R-T-B is in the manufacture method of alloy slice, alloy slice is made by the SC method, and not only mean thickness is set for from 0.1 to 1mm, and set melted alloy for every 1cm width 10g/sec or bigger to the average delivery rate of casting roll, be alloy so that obtain to have the R-T-B of high-coercive force.
Description of drawings
Fig. 1 illustrates the photo that R-T-B of the present invention is an example of alloy, and this photo is the photo that obtains when being the cross section of alloy slice by scanning electronic microscope (SEM) observation R-T-B;
Fig. 2 is the enlarged photograph of photo shown in Figure 1; And
Fig. 3 is the synoptic diagram of SC method casting device.
Description of reference numerals
1 refractory materials crucible
Bakie in the middle of 2
3 casting rolls
4 alloys
5 collection containers
Embodiment
Fig. 1 illustrates the photo that R-T-B of the present invention is an example of alloy, and this photo is the photo that obtains when being the cross section of alloy slice by scanning electronic microscope (SEM) observation R-T-B.
R-T-B shown in Figure 1 is that alloy is made by the SC method.This R-T-B is that the composition of alloy comprises 22% Nd, 9% Dy, 0.95% B, 1% Co, 0.3% Al and 0.1% Cu according to weight ratio, and all the other are Fe.Do not separating out R according to comprising in the composition of very big supercooled conventional SC method 2T 17Phase is even and under the equilibrium state of normal temperature, at R 2T 14Under 1170 ℃ of fusing points of B phase or the lower temperature, R 2T 17Can stably not exist mutually yet.In Fig. 1, rich R is by white indication, R 2T 17By than main R 2T 14B omits dark color indication mutually.
As shown in Figure 1, R-T-B is that alloy is fully by being R 2T 14The styloid of B phase is formed, and the hand down long axis direction of styloid of rich R extends.R 2T 14B mainly comprises styloid mutually, partly comprises equiaxed crystal, and its average crystalline particle diameter on short-axis direction is from 10 to 50 μ m.At R 2T 14B mutually in, in crystal boundary place and crystal grain, exist the linear rich R that extends along the long axis direction of styloid mutually or rich R phase granular or that part ruptures.Be present in R 2T 14The mean distance of rich R in the crystal boundary place of B phase and the crystal grain between mutually is from 3 to 10 μ m.Equally, as shown in Figure 1, be to exist in the alloy to allow very fine R at R-T-B 2T 17With the zone that rich R coexists mutually, each area percentage (volume percent) that occupies mutually is about 3%.
(1) R 2T 17Phase
At R-T-B shown in Figure 1 is in the alloy, R 2T 17Be intermetallic compounds mutually, it does not have the composition width of cloth from normal temperature to the high-temperature area stable existence in the binary phase diagram of rare-earth iron series.This is the soft magnetism phase of intra-face anisotropy at normal temperatures mutually, and in being present in the R-T-B based sintered magnet time, as the nucleation site of reverse domain so that coercive force reduces.Yet, even in raw alloy, there is very a spot of R 2T 17Phase, this phase also disappear in sintering process and become harmless under many circumstances.And, R 2T 17Therefore be not to be ductile and to influence the intermetallic compounds of the pulverizing behavior in the magnet manufacturing processed hardly mutually.
When the ratio such as the heavy rare earth element of Dy and Tb increases, R 2T 17Instead the first crystal of α-Fe is separated out mutually.R 2T 17Be soft magnetism and be different from α-Fe, as mentioned above, it is very little in the influence of pulverizing on the characteristic, and in the SC method, can similarly avoid R by very big undercooling and α-Fe 2T 17Generate.
(2) R 2T 17The crystal particle diameter of phase
Fig. 2 is the enlarged photograph of photo shown in Figure 1, and this photo illustrates among Fig. 1 with white line area surrounded and peripheral region thereof.In Fig. 2, R is shown with the white line area surrounded 2T 17The zone of separating out mutually.
At R-T-B is in the alloy, at R 2T 17Average crystalline particle diameter on the short-axis direction of phase is preferably less.At R-T-B shown in Figure 1 is in the alloy, and the average crystalline particle diameter is about from 1 to 2 μ m.As mentioned above, work as R 2T 17When the crystal particle diameter of phase became big, this disappeared when sintering hardly, and if remain in the sintered compact the residual deterioration that causes magnetic properties mutually.Can this be disappeared mutually by improving sintering temperature or prolonging sintering time, but the also alligatoring and cause coercitive decline of principal phase particle diameter.By will be at R 2T 17Average crystalline particle diameter on the short-axis direction of phase controls to 3 μ m or littler, can obtain effect of the present invention.
In remaining in sintered compact or by the raising of sintering temperature or the prolongation of time and the possibility that coercive force that causes or dihedral (squareness) reduce, thick R 2T 17The disadvantageous effect of phase is also as the decline of orientation degree (orientation rate) and occur.Two reasons are considered in decline for orientation degree.A reason is R 2T 17The intra-face anisotropy of phase.This magnetization on also with R 2T 14B is different mutually, and therefore in magnetic field shaping can influence R 2T 14The orientation behavior of B phase.As for second reason, consider little R 2T 17Phase and phase neighbour's R 2T 14B combines (zoarium) or is transformed into liquid phase, yet, work as R 2T 17Become greater to mutually and main R 2T 14During degree that the grain-size of B phase equates, disappearing can be time-consuming, and before disappearing, and this is met and equates that with adjacent rich B reaction is to produce and the R that grows 2T 14B examines mutually.Here, the R of new nucleation and growth 2T 14B has crystalline orientation at random mutually, and the therefore whole decline of orientation degree.
(3) comprise R 2T 17The volume percent in the zone of phase
In the present invention, will separate out R as shown in Figure 2 2T 17The zone definitions of phase is for " to contain R 2T 17Region ".Can easily pick out this zone from the part of alloy structure on every side, described around the alloy structure part comprise that mainly rich R that the principal phase of styloid and long axis direction along styloid extend mutually.
Especially, when at R 2T 17Median size on the short-axis direction of phase is 3 μ m or more hour, and sinterability and strengthen the above-mentioned effect of magnetic properties can be improved.The volume percent of this phase is preferably from 0.5 to 10%.If on short-axis direction, have the R of 3 μ m or littler median size 2T 17The volume percent of phase is lower than 0.5%, and the effect of improving sinterability and strengthening magnetic properties descends, and if the R that has 3 μ m or littler median size on short-axis direction 2T 17The volume percent of phase surpasses 10%, and then the fluctuation of composition when pulverizing or particle size is very big and cause the very great fluctuation process of magnetic properties, and since the decline magnetization of orientation degree reduce.The R that on short-axis direction, has 3 μ m or littler median size 2T 17The volume percent of phase more preferably is from 1 to 5%.Yet, if R 2T 17Median size on short-axis direction surpasses 5 μ m, separates out R 2T 17The effect of phase dies down, and if this R that contains 2T 17The volume percent of region surpasses 10%, and the magnetic properties fluctuation is very big.Equally, if R 2T 17Median size on short-axis direction is 10 μ m or bigger, and the volume percent of this phase is 10% or bigger, and then magnetic properties obviously worsens.Be included in the R that has 10 μ m or bigger median size on the short-axis direction 2T 17The volume percent in the zone of phase more preferably 5% or littler.
(4) R 2T 17The stability of phase
In a preferred embodiment of the invention, being present in R-T-B is R in the alloy 2T 17Exist as non-equilibrium phase (metastable phasing).Having, be not limited to formation R-T-B of the present invention as metastable phasing is the R of alloy 2T 17The precipitate of phase is under the upper state, and is therefore for example disappearing in the high-temperature area that is worked satisfactorily by about 1/2 time diffusion of the decomposition temperature shown in the absolute temperature of compound.R as the non-equilibrium phase existence 2T 17The needed time disappear mutually according to temperature or R 2T 17The size of phase and changing, but with the R that is present under the equilibrium state 2T 17Compare mutually, easily dissolved, and in the magnet manufacturing processed, this disappears in several hours or shorter common sintering time.
(5) rich R phase
In a preferred embodiment of the invention, as shown in Figure 2, having much at one, the rich R of size together is present in the R that R-T-B is an alloy mutually 2T 17Separate out the position mutually.Rich R became frangible by absorbing hydrogen-expansion in hydrogen cracking step before pulverizing, and be fine-powdered formation starting point.Because the coexistence of rich R phase contains R 2T 17Region compares R 2T 14B pulverizes finelyr mutually, and has further strengthened fine R 2T 17The effect of phase.And, obtain the good dispersion of rich R phase, and further improve sinterability.Yet, be 10 μ m if the median size on the short-axis direction of rich R phase is increased to about, the ratio that only comprises the fine powder of rich R phase increase and molding in uniformity descend, cause sinterability to worsen.The uniformity of the rich R phase in sintered compact also descends, and therefore coercive force descends.And it is frangible that the rich R of hydrogenant compares principal phase, and divide imperceptibly in very short time and increase the composition when pulverizing or the fluctuation of particle size in the starting stage of pulverizing, and this causes the fluctuation of characteristic.Therefore, the median size on the short-axis direction of rich R phase is preferably 3 μ m or littler.
(6) Strip casting method (SC method)
R-T-B of the present invention shown in Figure 1 is that alloy is the thin slice of making by the Strip casting method.For example, R-T-B of the present invention is that alloy can be by following SC method casting.
Fig. 3 is the synoptic diagram that SC method casting device is shown.Usually, because R-T-B is the character of enlivening of alloy, melting R-T-B by use refractory materials crucible 1 in vacuum or inert gas atmosphere is alloy.After fusing R-T-B is alloy, melted alloy remains on 1300 to 1500 ℃ of one section preset times, supply to the rotating roller that is used to cast 3 (casting roll) of inner water-cooled then by middle bakie 2, if desired, in the middle of described, be provided with rectification mechanism or bolt piece (slug) removal mechanism in the bakie.According to the delivery rate of required alloy gauge control melted alloy and the slewing rate of casting roll.Usually, the revolution of casting roll is about 0.5 to 3m/s according to circumferential speed.Because good heat conductivity and easy operability, the material of casting roll suitably is copper or copper alloy.According to the condition of surface of the material or the casting roll of casting roll, metal is easy to attached to the casting roll surface.Therefore, if desired, clearing apparatus can be set, the R-T-B that makes casting thus is the steady quality of alloy.On the opposite side of alloy 4 that solidifies on the casting roll, reclaim from the roller separation and by collection container 5 at middle bakie.Disclosing in JP-A-10-36949 can be by being provided with the structural state of the rich R phase of heating and cooling mechanism controls in collection container.In the present invention, in order to control the dispersion state of rich R phase, cooling after separating from roller and thermal insulation can be divided into several steps and be controlled thus.More specifically, for example, before finally collecting alloy, heating and cooling mechanism is set by collection container, and alloy is heated, adiabatic and cooling, the adjustment and the magnetic properties of shrinking percentage in the time of can improving supply, volume density, the sintering of size distribution, the metal mold of the fine powder after the size of alloy structure and uniformity, the pulverizing thus.
(7) alloy thickness
R-T-B of the present invention is that alloy is preferably and has 0.1 thin slice to the mean thickness of 1mm.If the mean thickness of thin slice is less than 0.1mm, solidification rate exceedingly raises, and rich R disperses mutually too imperceptibly, and if the mean thickness of thin slice surpasses 1mm, then solidification rate descends and this causes the separating out and R of reduction, α-Fe of the dispersiveness of rich R phase 2T 17The alligatoring of phase etc.
(8) deposite metal is to the average delivery rate of casting roll
The deposite metal is every 1cm width 10g/sec or bigger to the average delivery rate of casting roll, preferred 20g/sec or bigger, more preferably 25g/sec or bigger, most preferably every 1cm width 100g/sec or less than 100g/sec.If the delivery rate of deposite metal is less than 10g/sec, melted alloy can't be soaked into thinly and stretch (wriggling) on roller, but owing to melted alloy itself is shunk the viscosity or the wetting properties on casting roll surface, and cause the fluctuation of alloy mass, if and melted alloy arrives the delivery rate of casting roll above every 1cm width 100g/sec, then the cooling on the casting roll is not enough, and this causes separating out of the alligatoring organized and α-Fe etc.Can delivery rate be controlled to a certain degree by in middle bakie, rectification mechanism being set.
In the present invention, confirm, melted alloy stably and thinly is soaked on the roller surface and stretch required minimum melted alloy delivery rate, can easily make and have target and contain R by delivery rate being brought up to be higher than 2T 17The alloy of region.
(9) R-T-B is the average rate of cooling of alloy on casting roll
This is the value of calculating by the time that temperature before being about to contact casting roll in melted alloy and difference between the temperature when casting roll separates contact with casting roll divided by melted alloy.R-T-B is that the average rate of cooling of alloy on casting roll is preferably from 500 to 3000 ℃/sec.If average rate of cooling is less than 500 ℃/sec, then because the separating out of α-Fe, rich R phase and R take place insufficient rate of cooling 2T 17The microstructure coarsening of phase etc., and if average rate of cooling surpasses 3000 ℃/sec, then undercooling becomes too big and as the R that contains of feature of the present invention 2T 17The growing amount of region reduces.
(10) the R-T-B medial temperature that is alloy when casting roll separates
The medial temperature that R-T-B is an alloy when casting roll separates is because with the nuance of the exposure level of casting roll and the fluctuation of thickness etc. and change.For example, can be by beginning from casting to finishing to obtain the medial temperature of alloy when casting roll separates by the mean value that radiation thermometer broad ways scanning alloy surface is measured temperature and obtained observed value.
The medial temperature of alloy when casting roll separates is R under the equilibrium state of alloy than the R-T-B in fusing preferably 2T 14Low 100 to 400 ℃ of the temperature of solidification of B phase, more preferably low 100 to 300 ℃.R 2T 14The temperature of fusion of B phase is thought 1150 ℃ in the Nd-Fe-B three component system, but according to other rare earth element alternative, other transition element to Nd the alternative of Fe and other kind and add-on of adding element is changed.If the medial temperature that R-T-B is an alloy when casting roll separates with at R-T-B be R under the equilibrium state of alloy 2T 14Difference between the temperature of solidification of B phase is less than 100 ℃, and this is corresponding with insufficient rate of cooling, and if should difference surpass 400 ℃, the undercooling of melted alloy is owing to too high rate of cooling becomes excessive.The supercooled degree of melted alloy is uneven in alloy, but according to changing with the exposure level of casting roll or from the distance of contact part and casting roll.
As mentioned above, the temperature of alloy when casting roll separates also changes same casting step (tap of branch), and if rangeability very big, the fluctuation that can bring tissue or quality.Therefore, the variation of temperature amplitude in branch is suitably less than 200 ℃, and preferred 100 ℃ or littler, more preferably 50 ℃, most preferably 20 ℃.
If the medial temperature that R-T-B is an alloy when casting roll separates is than the R under the equilibrium state of melted alloy composition 2T 14Low 300 ℃ or bigger of the temperature of solidification of B phase, the R that then separates out 2T 17The amount of phase reduces, and the effect of improving magnetic properties dies down.This infers R 2T 17Separating out of phase is created in the less position of undercooling degree.Equally, if heavy rare earth element proportion in rare earth element descends the R that separates out 2T 17The amount of phase also reduces, and can not confirm the existence of this phase, but the effect of enhancing magnetic properties continues.This is considered to owing to suitably reducing the R that produces by solidification rate 2T 14The raising of the minimizing of the lattice defect of B phase and stability takes place.
In the Strip casting method, it is to need only crystal grain and do not become too fine, even rate of cooling is very high also no problem that tradition is understood.For example, in JP-A-08-269643, the cooling on the roller is called main cooling, and the document points out that preferably carrying out in rate of cooling to 700 to 1000 ℃ Strip casting temperature is 2 * 10 3To 7 * 10 3℃/ cooling under the sec.
(11) R-T-B based rare earth permanent magnet
In order to make R-T-B based rare earth permanent magnet of the present invention, be the fine powder that the alloy manufacturing is used for R-T-B based rare earth permanent magnet at first from R-T-B of the present invention.For example, by comprise R-T-B of the present invention be alloy thin slice the hydrogen cracking and then by using the method for pulverizing thin slice such as the pulverizer of jet mill to obtain to be used for the fine powder of R-T-B based rare earth permanent magnet of the present invention.For example, in the hydrogen cracking here, keep the hydrogen absorption step of thin slice in the nitrogen atmosphere under the predetermined pressure preferably to carry out in advance.
Then, with the fine powder that is used for R-T-B based rare earth permanent magnet that obtains for example by forming mill etc. at transverse magnetic field extrusion molding and sintering, obtain R-T-B based rare earth permanent magnet thus.
At R-T-B of the present invention is in the alloy, fine R 2T 17Phase or and R 2T 17Mutually the fine rich R that exists together is converted into liquid phase rapidly when sintering, thereby helps strengthening the sinterability or the dispersiveness of rich R phase, so that can obtain to have the rare-earth magnet of high-coercive force and good magnetic properties.
For example, contain R 2T 17Phase alloy comprises the R that contains by the acquisition of SC method 2T 17Bronze and the R as principal phase of having that obtains by the SC method are harmonious 2T 14The alloy powder phase blended alloy of B phase is to improve R 2T 14The volume percent of B phase (for example, seeing JP-A-7-45413).Yet, see the described R that contains of JP-A-7-45413 as Accessory Right claim and clarity of illustration ground 2T 17Phase alloy is arranged such that R 2T 17Separate out under equilibrium state owing to the minimizing of B amount mutually.In this case, R 2T 17Volume percent in alloy increases, and R in the alloy 2T 17The crystal particle diameter of phase also increases.Therefore, in order to make R 2T 17When sintering, disappear, need be with R 2T 17The particle size that comprises alloy powder is mutually done little.If particle size is not done for a short time, sintering temperature or prolong sintering time to obtain R then needs to raise 2T 17The necessary gratifying diffusion that disappears mutually, the result causes the microstructure coarsening of sintered compact and coercive force to reduce.Equally, be easy to infer the described R of JP-A-7-45413 from the composition configuration 2T 17Stably exist to its decomposition temperature from normal temperature.And JP-A-7-45413 points out R 2T 17The interpolation of phase can cause liquid phase to increase, but does not arrive liquid phase details before from the discussion of power aspect.
On the other hand, as mentioned above, constitute the R that R-T-B of the present invention is an alloy 2T 17Separate out as non-equilibrium phase.With the R that is under the equilibrium state 2T 17Compare mutually, as the R of non-equilibrium phase existence 2T 17Be easy to mutually disappear, and in the magnet manufacturing processed, in common several hours sintering time, disappear.
In above-mentioned example, illustrated to be used for making to have allowing to separate out R 2T 17The R-T-B of the composition of phase is the method for alloy, is not limited to be used to have and allows to separate out R but R-T-B of the present invention is the manufacture method of alloy slice 2T 17The R-T-B of the composition of phase is the method for alloy, and can be that the manufacture method manufacturing of alloy slice has and do not allow to separate out R by R-T-B of the present invention 2T 17The R-T-B of the composition of phase is an alloy.
Equally in this case, as what in the example of back, confirm, by according to R-T-B be the above-mentioned manufacture method of alloy slice to make R-T-B be alloy, the R-T-B that can obtain to have high-coercive force is an alloy.
Therefore a presumable reason is, when the above-mentioned manufacture method that by R-T-B is alloy slice was made, the lattice defect of alloy reduced.
(example 1)
Weigh feed metal neodymium, metal dysprosium, ferro-boron, cobalt, aluminium, copper and iron to provide alloying constituent, this alloying constituent comprises 22% Nd, 9% Dy, 0.95% B, 1% Co, 0.3% Al and 0.1 Cu according to weight ratio, all the other are Fe, by use the high frequency smelting furnace in argon atmospher under 1atm in alumina crucible the melted alloy composition, and by SC method casting melted alloy with the alloying sheet.
The rotating roller that is used to cast has the diameter of 600mm, by making by the Cr of trace and Zr are mixed the alloy that obtains with copper, and its inside of water-cooled.Roller is 1.3m/sec at the circumferential speed in when casting, and melted alloy is every 1cm width 28g/sec to the average delivery rate of casting roll, measure the medial temperature of alloy when casting roll separates by radiation thermometer, and discovery is 890 ℃.In observed value, the difference between top temperature and the minimum temperature is 35 ℃.Because the R of this alloy 2T 14The fusing point of B phase is about 1170 ℃, and therefore the difference with average separation temperature is 280 ℃.Equally, R-T-B is that the average rate of cooling of alloy on casting roll is 980 ℃/sec, and mean thickness is 0.29mm.Be used to hold from the returnable of the isolating alloy slice of roller and have the but division plate crossed of argon gas stream of cooling.Table 1 illustrates creating conditions of alloy slice.
[table 1]
Delivery rate (g) Rate of cooling (℃/sec) Temperature of solidification (℃) Mean temperature difference (℃) Mean thickness (mm) Median size 1 (μ m) Volume percent 1 (%) Median size 2 (μ m) Volume percent 2 (%) Median size 3 (μ m) Volume percent 3 (%)
Example 1 28 980 1170 280 0.29 1.5 3 ?- Do not have 2.1
Example 2 28 1060 1140 290 0.29 - Do not have ?- Do not have - Do not have
Comparative example 1 13 920 1170 540 0.23 - Do not have ?- Do not have - Do not have
Comparative example 2 13 930 1140 520 0.23 - Do not have ?- Do not have - Do not have
Comparative example 3 70 290 1170 170 1.2 - Do not have ?8 30 - Do not have
In table 1, " delivery rate " expression melted alloy is to the average delivery rate of casting roll, and this is the amount that every 1cm width per second is supplied with; " rate of cooling " expression R-T-B is the average rate of cooling of alloy on casting roll; " temperature of solidification " is R 2T 14B is the temperature of solidification (fusing point) under the equilibrium state of alloy at R-T-B; " mean temperature difference " expression " temperature of solidification " and R-T-B are the temperature head between the medial temperature of alloy when separating with casting roll; And " mean thickness " expression is by the mean thickness of the thin slice of Strip casting method manufacturing.
(assessment of alloy slice)
10 alloy slices that obtain of packing into are to take the back scattered electron picture (BEI) of each alloy slice 350 times by scanning electronic microscope (SEM) at enlargement ratio after polishing.The R that contains that is taken a picture by the image analyzer analysis 2T 17Region and each R that contains in the rich R region 2T 17Mutually with rich R short-axis direction mutually on the average crystalline particle diameter.And, with take a picture to be divided into and contain R 2T 17Region and the photo that contains rich R region, and from weight ratio volume calculated per-cent.Here, for containing R 2T 17Region is to having each R of 3 μ m or littler median size and 5 μ m or bigger median size in this zone 2T 17Phase volume calculated per-cent.The median size and the volume percent of each tissue of alloy slice are shown in table 1.
In table 1, median size 1 and volume percent 1 are illustrated in the R that has 3 μ m or littler median size on the short-axis direction 2T 17The median size of phase and comprise this R 2T 17The volume percent in the zone of phase; 2 expressions of median size 2 and volume percent are included in the R that has 5 μ m or bigger median size on the short-axis direction 2T 17The median size in the zone of phase and comprise this R 2T 17The volume percent in the zone of phase; And 3 expressions of median size 3 and volume percent are present in and are included in the R that has 3 μ m or littler median size on the short-axis direction 2T 17Median size and this regional volume percent of on short-axis direction, having the rich R phase of 3 μ m or littler median size in the zone of phase.
And the alloy slice of acquisition is 1000 ℃ of following thermal treatments 2 hours, and is to take the back scattered electron picture (BEI) of each alloy slice 350 times by scanning electronic microscope (SEM) at enlargement ratio, and the result has confirmed R 2T 17The completely dissolve of phase.This shows the R in the alloy slice 2T 17It before thermal treatment metastable phasing.Incidentally, apparent from the composition configuration, in the alloying constituent of example 1, R 2T 17Can not stably be present in mutually under 1170 ℃ or the lower temperature, this temperature is R 2T 14The fusing point of B phase.
(comparative example 1)
Mixing raw material with provide with example 1 in identical composition, and melt and pass through the casting of SC method in the same manner as in Example 1.Yet, the circumferential speed of roller is 0.8m/Sec when casting, melted alloy is every 1cm width 13.0g/sec to the average delivery rate of casting roll, the medial temperature of the alloy of measuring by radiation thermometer when casting roll separates is 630 ℃, and the top temperature and the difference between the minimum temperature that record temperature are 160 ℃.Because the R of this alloy 2T 14The fusing point of B phase is about 1170 ℃, and therefore the difference with average separation temperature is 540 ℃.Equally, R-T-B is that the average rate of cooling of alloy on casting roll is 920 ℃/sec, and mean thickness is 0.23mm.
Assess the alloy slice of acquisition in the mode identical, the results are shown in the table 1 with example 1.Incidentally, in comparative example 1, can not confirm that (affirmation) contains R 2T 17Region.
(example 2)
Hybrid metal neodymium, metal mistake, ferro-boron, cobalt, aluminium, copper and iron are to provide alloying constituent, this alloying constituent comprises 26.0% Nd, 5.0% Pr, 0.95% B, 1.0% Co, 0.3% Al and 0.1 Cu according to weight ratio, all the other are Fe, and melt and pass through the casting of SC method in the mode identical with example 1.Yet, the circumferential speed of roller is 1.3m/sec when casting, melted alloy is every 1cm width 28g/sec to the average delivery rate of casting roll, the medial temperature of the alloy of measuring by radiation thermometer when casting roll separates is 850 ℃, and the top temperature and the difference between the minimum temperature that record temperature are 20 ℃.Because the R of this alloy 2T 14The fusing point of B phase is about 1140 ℃, and therefore the difference with average separation temperature is 290 ℃.Equally, R-T-B is that the average rate of cooling of alloy on casting roll is 1060 ℃/sec, and mean thickness is 0.29mm.
Assess the alloy slice of acquisition in the mode identical, the results are shown in the table 1 with example 1.Incidentally, the R-T-B of example 2 is that the composition of alloy is configured to allow to separate out R 2T 17Phase, and in example 2, can not confirm to contain R 2T 17Region.
(comparative example 2)
Mixing raw material to be providing the composition identical with example 1, and melts and pass through the casting of SC method in the same manner as in Example 1.Yet, the circumferential speed of roller is 0.8m/sec when casting, melted alloy is every 1cm width 13.0g/sec to the average delivery rate of casting roll, the medial temperature of the alloy of measuring by radiation thermometer when casting roll separates is 620 ℃, and the top temperature and the difference between the minimum temperature that record temperature are 180 ℃.Because the R of this alloy 2T 14The fusing point of B phase is about 1140 ℃, and therefore the difference with average separation temperature is 520 ℃.Equally, R-T-B is that the average rate of cooling of alloy on casting roll is 930 ℃/sec, and mean thickness is 0.23mm.
Assess the alloy slice of acquisition in the mode identical, the results are shown in the table 1 with example 1.Incidentally, in comparative example 2, can not confirm to contain R 2T 17Region.
(comparative example 3)
Mixing raw material to be providing the composition identical with example 1, and melts and pass through the casting of SC method in the same manner as in Example 1.Yet, the circumferential speed of roller is 0.8m/sec when casting, melted alloy is every 1cm width 70g/sec to the average delivery rate of casting roll, the medial temperature of the alloy of measuring by radiation thermometer when casting roll separates is 1000 ℃, and the top temperature and the difference between the minimum temperature that record temperature are 250 ℃.Because the R of this alloy 2T 14The fusing point of B phase is about 1170 ℃, and therefore the difference with average separation temperature is 170 ℃.Equally, R-T-B is that the average rate of cooling of alloy on casting roll is 290 ℃/sec, and mean thickness is 1.2mm.
Assess the alloy slice of acquisition in the mode identical, the results are shown in the table 1 with example 1.In comparative example 3, even after 2 hours, also can confirm the R that contains of trace 1000 ℃ of following thermal treatments similarly in alloy slice and example 1 2T 17The existence of region.This is because the R that existed before thermal treatment 2T 17The grain-size of phase very big and this need mutually just to disappear for a long time to cause.Incidentally, similar to example 1 in the composition of comparative example 3, R 2T 17Can not stably be present in mutually under 1170 ℃ or the lower temperature, this temperature is R 2T 14The fusing point of B phase.
Below the example of sintered magnet is made in explanation.
(example 3)
The alloy slice that obtains in example 1 is pulverized through the hydrogen cracking and by jet mill.As the condition in the hydrogen absorption step of the preceding step of hydrogen cracking step is the pressure of 100% nitrogen atmosphere, 2atm and 1 hour hold-time.The temperature of metal strip when the hydrogen absorption reaction is initial is 25 ℃.As the condition in the dehydrogenation step of back step be in the vacuum atmosphere of 0.133hPa, hold-time of 500 ℃ and 1 hour.Subsequently, add the Zinic stearas powder of 0.07 quality %, under 100% nitrogen atmosphere, the powder that obtains is mixed fully, then pulverize by jet mill by V formula mixing machine to the powder of above acquisition.Atmosphere during pulverizing is the nitrogen atmosphere that is mixed with the oxygen of 4000ppm.Then, in 100% nitrogen atmosphere, pass through the complete once more mixed powder of V formula mixing machine.Oxygen concn is 2500ppm in the powdered material that obtains.Equally, from the analysis to the carbon concentration this powdered material, the Zinic stearas powder that is blended in the powdered material calculates work 0.05 quality %.
In 100% nitrogen atmosphere by forming mill in transverse magnetic field with the powdered material extrusion molding that obtains.Compacting pressure is 0.8t/cm 2, and the magnetic field in the die cavity is set to 15kOe.The powder that obtains passes through 1.33 * 10 -5Kept 1 hour down at 500 ℃ in the vacuum of hPa, afterwards 1.33 * 10 -5Kept 2 hours down at 800 ℃ in the vacuum of hPa, and also 1.33 * 10 -5Kept 2 hours and sintering down at 1030 ℃ in the vacuum of hPa.Sintered density is 7.7g/cm 3Or bigger, and this is enough big density.This sintered compact also in argon atmospher 530 ℃ of following thermal treatments 1 hour to make sintered magnet.
Measure the magnetic properties of this sintered compact of example 3 by DC B H waveform recorder, the results are shown in table 2.
[table 2]
Br T iHc kA/m (BH)max KJ/m3 SQ (％)
Example 3 1.16 2680 260 91
Example 4 1.45 1247 403 92
Comparative example 4 1.16 2551 259 91
Comparative example 5 1.45 1068 403 91
Comparative example 6 1.1 2425 234 90
In table 2, " Br " expression relict flux density, " iHc " represents coercive force, and " (BH) max " represents maximum magnetic energy product, and " SQ " represents dihedral.As for dihedral, when magnetization become saturation magnetization 90% the time, the value of external magnetic field is divided by iHc, the value that obtains is represented with %.
(comparative example 4)
The alloy slice that use obtains in comparative example 1, by with example 3 in identical method make sintered magnet.Measure the magnetic properties of the sintered compact of comparative example 4 by DC B H waveform recorder, the results are shown in table 2.
(example 4)
The alloy slice that use obtains in example 2, by with example 3 in identical method make sintered magnet.Measure the magnetic properties of the sintered compact of example 4 by DC B H waveform recorder, the results are shown in table 2.
(comparative example 5)
By with example 3 in identical method pulverize the alloy slice that in comparative example 2, obtains, to obtain fine powder.Measure the magnetic properties of the sintered compact of comparative example 5 by DC B H waveform recorder, the results are shown in table 2.
(comparative example 6)
By with example 3 in identical method pulverize the alloy slice that in comparative example 2, obtains, to obtain fine powder.Measure the magnetic properties of the sintered compact of comparative example 6 by DC B H waveform recorder, the results are shown in table 2.
As shown in table 2, be to be that the example 3 of the manufacture method manufacturing of alloy slice is compared with alloy by R-T-B of the present invention, can not confirm to contain R 2T 17Region and mean temperature difference surpass in 300 ℃ the comparative example 4, and (iHc) is low for coercive force.Its reason is estimated as by the R that contains in the alloy of example 1 2T 17Region has improved sinterability.
Equally, compare, using R with example 3 2T 17In the comparative example 6 of the alloy of the comparative example 3 that the particle diameter of phase and volume percent are big, coercive force (iHc) and maximum magnetic energy product ((BH) max) descend.
And, the comparative example 5 that surpasses 300 ℃ with mean temperature difference is compared, passing through in the example 4 that R-T-B of the present invention is the alloy made of the manufacture method of alloy slice of usage example 2, coercive force is big, and the alloy of example 2 has and do not comprise heavy rare earth element and do not allow to separate out R 2T 17The composition of phase.Its former carrying on as before under study for action, but therefore a presumable reason is owing to hang down solidification rate, the comparatively small amt of lattice defect in the alloy of example 2.

Claims (12)

1. a R-T-B is an alloy, and wherein R is at least a composition that is selected from the rare earth element that comprises Y, and T is the transition metal that must comprise Fe, and B is a boron, and this alloy is the raw material that is used for the rare earth class permanent magnet,
Wherein be included in the R that has 3 μ m or littler median size on the short-axis direction 2T 17The volume percent in the zone of phase is from 0.5 to 10%.
2. R-T-B according to claim 1 is an alloy, it is characterized in that, allows to have on short-axis direction the R of 3 μ m or littler median size 2T 17The volume percent in the zone that coexists mutually with the rich R that has 3 μ m or littler median size on short-axis direction is from 0.5 to 10%.
3. R-T-B according to claim 1 and 2 is an alloy, it is characterized in that, is included in the R that has 10 μ m or bigger median size on the short-axis direction 2T 17The volume percent in the zone of phase is 10% or littler.
4. R-T-B according to claim 1 and 2 is an alloy, it is characterized in that, is included in the R that has 5 μ m or bigger median size on the short-axis direction 2T 17The volume percent in the zone of phase is 10% or littler.
5. R-T-B according to claim 1 and 2 is an alloy, it is characterized in that described R 2T 17Be non-equilibrium phase mutually.
6. R-T-B according to claim 1 and 2 is an alloy, it is characterized in that, described alloy is 0.1 thin slice to the mean thickness of 1mm that has by the manufacturing of Strip casting method.
7. one kind is the method for alloy slice by Strip casting method manufacturing R-T-B, comprises and sets mean thickness for 0.1 to 1mm, and set melted alloy for every 1cm width 10g/sec or bigger to the average delivery rate of casting roll.
8. according to claim 7 being used to made the method that R-T-B is an alloy slice, it is characterized in that, and be from 500 to 3000 ℃/sec so described R-T-B is the average rate of cooling of alloy on casting roll.
9. make the method that R-T-B is an alloy slice according to claim 7 or 8 described being used to, it is characterized in that, the medial temperature that described R-T-B is an alloy when described casting roll separates is R under the equilibrium state of alloy than described R-T-B 2T 14Low 100 to 400 ℃ of the temperature of solidification of B phase.
10. one kind is that the R-T-B of alloy slice manufacture method manufacturing is an alloy by R-T-B according to claim 7.
11. one kind with being the fine powder that is used for R-T-B based rare earth permanent magnet of alloy manufacturing according to claim 1 or 10 described R-T-B.
12. R-T-B based rare earth permanent magnet made from the fine powder that is used for R-T-B based rare earth permanent magnet according to claim 11.
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