Detailed Description
We have found that the embodiment of the present invention can provide H having a variation in the amount of B by forming Ti boride in the R-T-B sintered magnet in the production process by setting the amount of Ti, the amount of B, and the amount of C in appropriate rangescJHas a small variation and a high BrAnd high HcJThe R-T-B sintered magnet of (1).
1. With respect to addition of Ti and C
The present inventors confirmed that: the R-T-B sintered magnet of the present invention has a boride (TiB and/or TiB) of Ti formed therein2). Further, the present invention is such that BC described latereffThe amount of B in the sintered magnet is smaller than that in a conventional R-T-B sintered magnet. Based on these, the inventors thought that H was changed even if the amount of B was changed by including Ti in a predetermined contentcJThe mechanism by which the change of (b) is also suppressed is as follows. Note that the mechanism shown below is not intended to limit the technical scope of the present invention.
As described above, the amount of B is reduced (compared with R) in the conventional R-T-B sintered magnet2T14B amount of the B type compound is small in stoichiometric ratio), and a sintered magnet having a composition in which Ga or the like is added can obtain high HcJ。
This is considered to be due to the fact that when the amount of B is lower than R2T14When the stoichiometric ratio of the type B compound is such that R and T become excessive, R is produced2T17In general, the magnetic properties of the phase sharply decrease as the amount of B decreases, but when Ga is contained in the magnet composition, R is substituted for Ga2T17Phase formation of R-T-Ga phase, thereby obtaining high HcJ。
In addition, when C is contained in a large amount in a general R-T-B sintered magnet, a high H content cannot be obtainedcJTherefore, we consider the ratio R of the B amounts in this way2T14In R-T-B sintered magnets having a low stoichiometric ratio of B-type compound, even when C is contained in a large amount, a high H content cannot be obtainedcJ. However, the present inventors have found that the amount of B is less than that of R2T14In the stoichiometric ratio of the type B compound, even if C is increased to an amount exceeding the level of unavoidable impurities (about 0.03 to 0.09% by mass), a high H content can be obtained by satisfying the relationships of the formulae (1) to (10), (A) and (B) of the present invention with respect to the amount of Ti, the amount of B and the amount of CcJ. The C content may exceed the level of inevitable impurities due to the addition of a mold release agent during molding, etc., and high H may not be obtainedcJ. Even in this case, the embodiment of the present invention can obtain high HcJ。
High H can be obtained even if C is increased to an amount exceeding the level of inevitable impuritiescJThe reason for this is considered as follows: when the amount of B is in proportion to R2T14When the stoichiometric ratio of the B-type compound is large, C which is mainly a grain boundary phase of rare earth carbide or the like is contained, and the amount of B is smaller than R2T14In the stoichiometric ratio of the compound of type B, R is substituted for B2T14Part of the B site of a type B compound. As described above, the amount of B is smaller than that of R2T14In the stoichiometric ratio of the compound of type B, the B site is easily replaced by C instead of B, so that C is particularly increased to inevitable impuritiesWhen the amount level is not less than about 0.03 to 0.09% by mass, the ratio R must be such that the total of the amount B and the amount C (amount B + amount C) is larger than the ratio R2T14The stoichiometric ratio of the type B compound is small. Further, as a result of the studies by the present inventors, it was found that: by adding Ti to a content within a specific range, boride of Ti is generated in the production process, and the B amount + C amount obtained by subtracting the B amount consumed by bonding with Ti in the production process from the B amount + C amount of the whole R-T-B sintered magnet (hereinafter, the remaining B amount + C amount not bonded with Ti is referred to as "effective B amount + C amount", and may be referred to as "BC" in some caseseffAmount') is smaller than the total amount of B + C in a general R-T-B sintered magnet (than the amount of R)2T14B amount + C amount of the B type compound in stoichiometric ratio) and a composition of Ga or the like, H with respect to the change in the B amountcJIs suppressed.
As described above, in the case of the sintered magnet having a composition in which the amount of B is reduced as compared with the conventional R-T-B sintered magnet and Ga is added, H is added when the amount of B is changedcJAnd significantly changed. This is considered to be because the amount of R-T-Ga phase formed depends on the amount of B + C relative to the amount of R2T14The stoichiometric ratio of the compound of type B is significantly changed by how much less (R, T remains), and therefore, HcJThe amount of B (2) had a large dependence, but it was found that: boride (TiB and/or TiB) is formed by adding Ti to a sintered magnet2) And the BC is subjected toeffIn an amount less than R2T14The stoichiometric ratio of B to H can be reduced by using B as the amount of the B-type compoundcJThe amount of B in the entire magnet.
This is considered to be due to BC formation of Ti boride according to the present inventioneffWhen the amount is smaller than the amount of B in a general R-T-B sintered magnet, Ga is added to the magnet to thereby form R2T17The equivalent production is suppressed and R-T-Ga is produced, as a result HcJIncrease, however, in this case, when the B amount and R amount of the entire magnet composition2T14TiB and TiB when the stoichiometric ratio of B to B of the type B compound is changed2Change of the generation ratio of (a), i.e. the amount of B and the sum of R of the entire composition of the magnet2T14When the difference between the amount of B determined from the stoichiometric ratio of the type B compound is small (that is, the amount of B contained is small), the amount of B is compared with TiB2In contrast, more TiB was generated, and in contrast, the amount of B and the sum of R were made up of the magnet as a whole2T14When the difference in the amount of B obtained from the stoichiometric ratio of the type B compound is large (that is, when the amount of B contained is large), more TiB is produced than TiB2. Thus, the more B-rich Ti boride (TiB) is produced2) When B is less, Ti boride (TiB) which is poor in B is generated, and even if the B content of the entire magnet changes, the B content + C content (BC) of the magnet which is not formed with Ti can be reducedeffAmount) of the component (B), and as a result, the amount of the R-T-Ga phase produced can be reduced relative to the amount of the B, and H can be suppressedcJA change in (c).
Further, the present inventors have confirmed that: when Ti is thus added, the ratio to R2T14The stoichiometric ratio of the type B compound is reduced by the amount of B + the amount of C, and high B can be obtained in the same manner as the effects observed in the sintered magnet containing Ga (sintered magnet as described in patent documents 1 and 2)rAnd high HcJ。
The term "R-T-Ga phase" as used herein means a phase containing R20 at% or more and 35 at% or less, T55 at% or more and 75 at% or less, and Ga 3 at% or more and 15 at% or less, and typically includes R6T13Ga1A compound is provided. Since Al, Si, etc. are mixed as inevitable impurities into the R-T-Ga phase, R may be, for example, R6T13(Ga1-i-yAliSiy) A compound is provided.
As a result of further studies based on the above, it was found that the amount of R-T-Ga phase produced can be controlled within an appropriate range by satisfying the formulae (A) and (B) with the amount of Ti, B and C, and therefore H can be suppressed from varying with the amount of BcJAnd high B is obtainedrAnd high HcJ0。
-0.02≤(g’+v’+z’)-(14×(w’+a’-2×q’)) (A)
0.02≥(g’+v’+z’)-(14×(w’+a’-q’)) (B)
Here, g 'is a value obtained by dividing g by the atomic weight of Fe (55.845), v' is a value obtained by dividing v by the atomic weight of Co (58.933), z 'is a value obtained by dividing z by the atomic weight of Al (26.982), w' is a value obtained by dividing w by the atomic weight of B (10.811), a 'is a value obtained by dividing a by the atomic weight of C (12.0107), and q' is a value obtained by dividing q by the atomic weight of Ti (47.867).
The following describes the formulae (A) and (B).
At the above BCeffIn an amount less than R2T14In the stoichiometric ratio of the B-type compound, Fe and Co and Al which can easily substitute for the Fe site of the main phase become excessive (the total ratio R of Fe and Co and Al)2T14The stoichiometric T amount of the compound of type B becomes excessive). Thus, all Ti forms TiB2When (i.e., Ti is bonded to the largest amount of B), BC is used in order to make the above-mentioned BCeffQuantitative ratio R2T14The stoichiometric ratio of the B-type compound is such that the amount of B is small that [ (g '+ v' + z ') - (14 × (w' + a '-2 × q'))](the total of Fe, Co and Al which do not form the main phase) is more than 0(Fe and Co and Al become excessive). However, it is considered that C is not necessarily used for R in its entirety2T14A compound of type B, even [ (g '+ v' + z ') - (14 × (w' + a '-2 × q'))]The amount of Fe, Co and Al (the total of Fe, Co and Al not forming the main phase) is slightly less than 0, and the amount of Fe, Co and Al may be excessive, and the effect of the present invention can be obtained when the amount is-0.02 or more. Therefore, the formula (A) specifies that the total of Fe, Co and Al which do not form the main phase is-0.02 or more. By setting the ratio to-0.02 or more, the R-T-Ga phase can be appropriately produced. The formula (a) can be obtained by calculation using values (g ', v', z ', w', a ', q') obtained by dividing the analysis values of Fe (g), Co (v), Al (z), B (w), C (a), and Ti (q) by the atomic weights of Fe, Co, Al, B, C, and Ti, respectively. The same applies to the formula (B) described later.
Further, the formula (B) of the present invention specifies that [ (g '+ v' + z ') - (14 × (w' + a '-q') ], when all Ti forms TiB (that is, Ti is bonded to the minimum amount of B)](the total of Fe, Co and Al which do not form the main phase) is 0.02 or less. This is because Fe, Co, which do not form a main phase,When the total amount of Al exceeds 0.02, the ratio of R-T-Ga phase becomes too high, the ratio of main phase decreases, and B cannot be obtained at a high levelrThe worry of (1).
2. Composition of
The composition of the R-T-B sintered magnet of the present invention will be described in detail below.
As described above, in the present invention, the BC is formed by adding Ti and producing boride of TieffThe amount of the component is smaller than that of B in a general R-T-B sintered magnet, and Ga is contained therein. Therefore, an R-T-Ga phase is formed in the grain boundary, and high H can be obtained even if the content of heavy rare earth elements such as Dy is suppressedcJ。
The composition of the R-T-B sintered magnet of the present invention can be represented by formula (1).
uRwBaCxGazAlvCoqTigFejM (1)
(R is at least one of rare earth elements and essentially contains Nd, M is an element other than R, B, C, Ga, Al, Co, Ti and Fe, and u, w, a, x, z, v, q, g, j represent mass%)
29.0≤u≤34.0 (2)
(wherein the heavy rare earth element RH is 10 mass% or less of the R-T-B sintered magnet)
0.80≤w≤0.92 (3)
0.10≤a≤0.20 (4)
0.3≤x≤0.8 (5)
0.05≤z≤0.5 (6)
0≤v≤3.0 (7)
0.15≤q≤0.29 (8)
58.29≤g≤69.60 (9)
0≤j≤2.0 (10)
The compositional ranges of the respective elements, that is, the numerical ranges of u, w, a, x, z, v, q, g, j will be described below.
1) Rare earth elements (R)
In the R-T-B sintered magnet of the present invention, R is at least one of rare earth elements and Nd is essentially contained. The R-T-B sintered magnet of the present invention can obtain high B content without using heavy rare earth element RHrAnd high HcJTherefore, even higher H is requiredcJIn this case, the amount of the heavy rare earth element RH to be added can be reduced, and typically, the heavy rare earth element RH may be 10 mass% or less, preferably 5 mass% or less.
The content of R is 29.0 to 34.0% by mass, preferably 29.0 to 32.0% by mass as shown in the formula (2).
29.0≤u≤34.0 (2)
When R is less than 29.0% by mass, R necessary for forming a sufficient amount of R-T-Ga phase cannot be obtained, and high H cannot be obtainedcJWhen the content exceeds 34.0% by mass, the main phase ratio decreases, and high B content cannot be obtainedr。
2) Boron (B), carbon (C)
The content of B is 0.80-0.92% by mass as shown in the formula (3).
The content of C is 0.10-0.20% by mass as shown in the formula (4).
0.80≤w≤0.92 (3)
0.10≤a≤0.20 (4)
When B is less than 0.80 mass%, BC is not added in a large amounteffThe amount becomes too small. On the other hand, when the amount of C exceeds 0.20 mass%, the ratio of carbon distributed to the grain boundary phase increases, so that when the amount of B is less than 0.80 mass%, BC is added even if a large amount of C is addedeffThe amount is also reduced, R is precipitated2T17Phase, high H cannot be obtainedcJ(ii) a Or the ratio of the main phase is lowered, and high B cannot be obtainedr. When the B content exceeds 0.92% by mass, the formation of the R-T-Ga phase becomes insufficient, and a high H content cannot be obtainedcJThe worry of (1).
3) Gallium (Ga)
The content of Ga is 0.3 to 0.8 mass% as shown in the formula (5).
0.3≤x≤0.8 (5)
When Ga is less than 0.3 mass%, the amount of R-T-Ga phase produced is too small to cause R to be present in an amount of2T17Phase disappearance with failure to obtain high HcJWhen the content exceeds 0.8% by mass, excessive Ga is present, the main phase ratio is lowered, and B is presentrReduced concerns.
4) Aluminum (Al)
The content of Al is 0.05 to 0.5 mass% as shown in the formula (6).
0.05≤z≤0.5 (6)
By containing Al, H can be increasedcJ. Al may be contained as an inevitable impurity or may be contained by being positively added. When Al exceeds 0.5 mass%, B is presentrReduced concerns. The content is 0.05 mass% or more and 0.5 mass% or less in terms of the total of the amount contained as an unavoidable impurity and the amount positively added.
5) Cobalt (Co)
The content of Co is 3.0 mass% or less as shown in the formula (7).
0≤v≤3.0 (7)
Co may be contained in an amount of 3.0 mass% or less. Co is effective for improving temperature characteristics and corrosion resistance, but if the Co content exceeds 3.0 mass%, B cannot be obtained at a high levelrThe worry of (1).
6) Titanium (Ti)
The content of Ti is 0.15 to 0.29 mass% as shown in the formula (8).
0.15≤q≤0.29 (8)
When Ti is less than 0.15% by mass, H due to variation in the amount of B cannot be suppressedcJIf the amount exceeds 0.29% by mass, the main phase ratio may be lowered, and a high B content may not be obtainedrThe worry of (1). Preferably, the content is 0.18 mass% or more and 0.28 mass% or less as shown in the following formula (11). H caused by the change of B amount can be further suppressedcJA change in (c).
0.18≤q≤0.28 (11)
7) Iron (Fe)
The content of Fe is 58.29-69.60% by mass, preferably 60.29-69.60% by mass, as shown in formula (9).
58.29≤g≤69.60 (9)
If Fe is less than 58.29 mass%, the main phase ratio decreases, and high B content may not be obtainedrWhen the content exceeds 69.60 mass%, the amount of R-T-Ga required for the formation is equal to or more than the required amount, andthe ratio of main phase is lowered, and B cannot be obtained highrThe worry of (1).
8) Element M
M is an element other than R, B, C, Ga, Al, Co, Ti and Fe.
As shown in the formula (10), the element M other than R, B, C, Ga, Al, Co, Ti and Fe may be contained in an amount of 2.0 mass% or less in total.
0≤j≤2.0 (10)
That is, the formula (10) indicates that an arbitrary element (may be plural elements) and inevitable impurities (except Al when Al is an inevitable impurity) may be contained in a total amount of 2.0 mass% or less in order to improve the characteristics and the like of the obtained R-T-B-based sintered magnet.
The element for improving the characteristics of the R-T-B sintered magnet may be, for example, Cu, Ni, Ag, Au, Mo or the like in an amount of 0 to 2.0 mass%.
Particularly preferably contains Cu. By containing Cu, high H can be obtainedcJ. The more preferable content of Cu is 0.05 mass% or more and 1.0 mass% or less.
In one preferred embodiment of M, M is composed of inevitable impurities (in which Cu is preferably contained as described above). Examples of the inevitable impurities contained in the R-T-B-based sintered magnet of the present invention include inevitable impurities usually contained in industrial raw materials such as didymium alloy (Nd-Pr alloy), electrolytic iron, and ferroboron. Examples of such unavoidable impurities include Cr, Mn, and Si. Further, as inevitable impurities in the production process, O (oxygen), N (nitrogen), and the like can be exemplified.
In the evaluation of the contents (% by mass) of R, B, C, Ga, Al, Co, Ti, Fe and M shown in the formula (1), i.e., u, w, a, x, z, v, q, g and j, high frequency inductively coupled plasma emission spectroscopy (ICP emission spectroscopy, ICP-OES) can be used, for example. In addition, for the evaluation of the oxygen amount, for example, a gas analyzer based on a gas melting-infrared absorption method; for the evaluation of the nitrogen amount, for example, a gas analyzer based on a gas melting-heat transfer method; for the evaluation of the amount of C, a gas analyzer based on a combustion-infrared absorption method, for example, can be used.
Method for producing R-T-B sintered magnet
An example of the method for producing an R-T-B sintered magnet according to the present invention will be described. A method for producing an R-T-B sintered magnet includes a step of obtaining an alloy powder, a forming step, a sintering step, and a heat treatment step. The respective steps will be explained below.
(1) Process for obtaining alloy powder
Metals or alloys of the respective elements are prepared so as to have a predetermined composition, and are melted and cast to obtain an alloy having a predetermined composition. Typically, a strip casting method or the like is used to produce a flake alloy. The obtained flake-like raw material alloy is subjected to hydrogen pulverization (coarse pulverization), and the size of the coarse pulverized powder is set to, for example, 1.0mm or less. Then, the coarsely pulverized powder is finely pulverized by a jet mill or the like to obtain, for example, a finely pulverized powder (alloy powder) having a particle diameter D50 (volume-based median particle diameter obtained by a laser diffraction method based on an air-flow dispersion method) of 3 to 7 μm. The alloy powder may be 1 type of alloy powder (single alloy powder), may be obtained by a so-called 2-alloy method in which 2 or more types of alloy powders are mixed to obtain an alloy powder (mixed alloy powder), or may be prepared so as to have the composition of the present invention by a known method or the like. Known lubricants can also be used as auxiliaries in the coarsely pulverized powder before the jet mill pulverization, in the jet mill pulverization, and in the alloy powder after the jet mill pulverization.
In the production of a raw material alloy by a belt casting method or the like, Ti may be added in the form of Ti metal, Ti alloy, Ti-containing compound, or the like when obtaining a molten metal for casting, and the molten metal containing Ti may be obtained and then solidified. Furthermore, this method is replaced. The Ti metal, Ti alloy or Ti-containing compound may be added in the form of Ti metal, Ti alloy or Ti-containing compound during the period from the preparation of the raw material alloy to the time before the forming, and examples thereof include alloys before and after the hydrogen pulverization and after the pulverization by a jet millAddition of Ti hydride (TiH) to the powder2Etc.).
(2) Shaping step
The obtained alloy powder was molded in a magnetic field to obtain a molded body. Shaping in a magnetic field any known shaping in a magnetic field method can be used, including: the dry molding method, in which dry alloy powder is inserted into a cavity of a mold and molding is performed while applying a magnetic field, and the wet molding method, in which slurry in which alloy powder is dispersed is injected into the cavity of the mold and molding is performed in a magnetic field while discharging a dispersion medium of the slurry.
(3) Sintering step
The formed body is sintered to obtain a sintered magnet. The molded body can be sintered by a known method. In order to prevent oxidation by the atmosphere during sintering, sintering is preferably performed in a vacuum atmosphere or in an inert gas. As the inert gas, an inert gas such as helium or argon is preferably used.
(4) Heat treatment Process
The sintered magnet obtained is preferably subjected to a heat treatment for the purpose of improving the magnetic properties. The heat treatment temperature, heat treatment time, and the like may be set to known conditions. The sintered magnet obtained may be subjected to mechanical processing such as grinding for the purpose of forming a final product shape or the like. In this case, the heat treatment may be performed before or after the machining. Further, the obtained sintered magnet may be subjected to surface treatment. The surface treatment may be a known surface treatment, and may be, for example, a surface treatment such as Al vapor deposition, Ni plating, or resin coating.
[ examples ] A method for producing a compound
< Experimental example 1 >
Nd metal, Pr metal, ferroboron alloy, iron-carbon alloy, Ga metal, Cu metal, Al metal, electrolytic Co, Ti metal, and electrolytic iron (all metals having a purity of 99% or more) were mixed so as to have the composition shown in Table 1, and these raw materials were melted and cast by a belt casting method to obtain a sheet-like raw material alloy having a thickness of 0.2 to 0.4 mm. The obtained flake-like raw material alloy was subjected to hydrogen pulverization in a hydrogen pressurized atmosphere, and subjected to dehydrogenation treatment in which heating to 550 ℃ and cooling were carried out in vacuum, to obtain a roughly pulverized powder.
Then, 0.04 parts by mass of zinc stearate as a lubricant was added to 100 parts by mass of the obtained coarse pulverized powder, and after mixing, the mixture was dry-pulverized in a nitrogen stream by a jet mill to obtain a particle diameter D50A 4 μm fine powder (alloy powder). In the present experimental example, the oxygen content of the finally obtained sintered magnet was about 0.1 mass% by setting the oxygen concentration in the nitrogen gas at the time of pulverization to 50ppm or less. Further, the particle diameter D50Is a value (volume-based median particle diameter) obtained by a laser diffraction method based on an air-flow dispersion method.
The finely pulverized powder was mixed with zinc stearate as a lubricant in an amount of 0.05 part by mass per 100 parts by mass of the finely pulverized powder, and then molded in a magnetic field to obtain a molded article. The molding apparatus is a so-called right-angle magnetic field molding apparatus (transverse magnetic field molding apparatus) in which the magnetic field application direction and the pressing direction are orthogonal to each other.
The obtained compact is sintered by holding it at 1070 to 1090 ℃ for 4 hours in vacuum depending on the composition, and then quenched to obtain a sintered magnet.
The density of the sintered magnet was 7.5Mg/m3The above. The analysis results of the composition of the obtained sintered magnet are shown in table 1. The components in table 1 were measured by high frequency inductively coupled plasma optical emission spectrometry (ICP-OES). Further, O (oxygen amount) was measured using a gas analyzer based on a gas melting-infrared absorption method; n (nitrogen amount) was measured using a gas analysis apparatus based on a gas melting-heat transfer method; the C (carbon amount) was measured using a gas analyzer based on a combustion-infrared absorption method. In table 1, the total of the amounts of Nd and Pr is the R amount (u), and the total of the amounts of Cu, Cr, Mn, Si, O, and N, which are elements other than R, B, C, Ga, Al, Co, Ti, and Fe, is the M amount (j). The same applies to tables 3, 5 and 7 described later. Values (g'V ', z ', w ', a ', q '), and the values used to calculate (g ' + v ' + z ') - (14 × (w ' + a ' -2 × q ') (a) and (g ' + v ' + z ') - (14 × (w ' + a ' -q ')) of formula (B) are "○" when they are within the scope of the present invention and "x" when they are outside the scope of the present invention, and are described in the columns of "formula a" and "formula B" in table 1, the same applies to tables 3, 5 and 7 shown below, and it is noted that, as shown in table 1, sample nos. 1 to 3, 4 and 5, 6 and 7, 8 and 9, 11 to 14, 17 and 18, 20 and 21 have substantially the same composition except for the amount of B.
[ TABLE 1 ]
The sintered magnet obtained was subjected to a heat treatment of holding at 900 ℃ for 2 hours, then cooling to room temperature, and then holding at 480 ℃ for 2 hours, and then cooling to room temperature. The sintered magnet after heat treatment was machined to prepare samples having a length of 7mm, a width of 7mm and a thickness of 7mm, the samples were magnetized with a pulsed magnetic field of 3.2MA/m, and B of each sample was measured by a B-H plotterrAnd HcJ. The measurement results are shown in Table 2. In addition, for the measurement of BrAnd HcJThe results of analyzing the composition and gas of the R-T-B sintered magnet of (1) were the same as those of the R-T-B sintered magnet material of Table 1.
Furthermore, H in samples Nos. 1 to 3, 4 and 5, 6 and 7, 8 and 9, 11 to 14, 17 and 18, 20 and 21 was changed in accordance with the amount of BcJThe change in (c) was determined as follows.
First, the difference in the amount of B in 2 samples (of samples having substantially the same composition except the amount of B) among the respective samples was determined, and H in 2 samples of the same composition was determinedcJA difference of (A) from (B) to (H)cJIs divided by the difference in the amount of B to determine H when the amount of B is changed by 0.01 mass%cJHow much it has changed. When a plurality of samples are present, H is selected when the amount of B is changed by 0.01 mass%cJThe most varied value. For example, H in samples Nos. 11 to 14cJThe change in (c) was determined as follows.
First, among samples No.11 to 14, sample No. 11H was usedcJH1380 kA/m and sample No.12cJWhen the B amount was changed by 0.01 mass% obtained by dividing the difference 51kA/m of 1431kA/m by the difference 0.03 mass% between the B amount of sample No.11 and the B amount of sample No.12 of 0.86 mass%cJThe change was 17kA/m (51/(0.03X 100)). This is the maximum value in the combination of 2 samples selected from 4 samples of sample Nos. 11 to 14.
Similarly, sample nos. 1 to 3, 4 and 5, 6 and 7, 8 and 9, 17 and 18, 20 and 21 were also calculated. The results are shown in "Δ H" of Table 2cJColumn of/0.01B ". Δ H in tables 6 and 8 shown belowcJThe same applies to 0.01B.
[ TABLE 2 ]
As shown in Table 2, the samples of examples of the present invention, sample Nos. 6 and 7, 8 and 9, 11 to 14, 17 and 18, had Δ HcJ0.01B 29kA/m or less, H with respect to the change in the amount of BcJIs small and a high B is obtainedrAnd high HcJ. In contrast, in sample Nos. 1 to 3, 4 and 5, in which the Ti content is lower than the range of the present invention,. DELTA.HcJH where 0.01B is 52kA/m or more and the amount of B is changedcJIs larger than that of the example sample, therefore, when the amount of B is increased, H is increasedcJDecrease (for example, 1328kA/m in sample No. 3) and failure to obtain a high HcJFurthermore, sample Nos. 20 and 21 having Ti contents higher than the range of the present invention similarly showed H with respect to the change in B contentcJIs larger than that of the example sample, and further, a higher B content than that of the example sample cannot be obtainedrAnd high HcJ. Furthermore, it is clear from sample Nos. 11 to 14, 17 and 18 which are examples of the present invention that when Ti is 0.19 mass% or more, Δ H is observedcJH where 0.01B is 17kA/m or less and further varies with the amount of BcJThe variation of (2) is small.
Further, as shown in Table 2, samples No.10 and 15 do not satisfy the formula (A)) And (B), sample No.16 having an amount of B out of the range of the present invention, and sample No.19 having an amount of C out of the range of the present invention, compared with the example samples of the present invention, the comparative example sample HcJGreatly reducing the cost.
< Experimental example 2 >
Nd metal, Pr metal, ferroboron alloy, iron-carbon alloy, Ga metal, Cu metal, Al metal, electrolytic Co, and electrolytic iron (all metals having a purity of 99% or more) were mixed so as to have the composition shown in Table 3, and these raw materials were melted and cast by a belt casting method to obtain a sheet-like raw material alloy having a thickness of 0.2 to 0.4 mm. The obtained flake-like raw material alloy was subjected to hydrogen pulverization in a hydrogen pressurized atmosphere, and subjected to dehydrogenation treatment in which the alloy was heated to 550 ℃ in vacuum and cooled to obtain a roughly pulverized powder. Then, 0.04 parts by mass of zinc stearate as a lubricant was added to 100 parts by mass of the obtained coarse pulverized powder, and after mixing, the mixture was dry-pulverized in a nitrogen stream by a jet mill to obtain a particle diameter D50A 4 μm fine powder (alloy powder). In the present experimental example, the oxygen content of the finally obtained sintered magnet was about 0.15 mass% by setting the oxygen concentration in the nitrogen gas at the time of pulverization to 100ppm or less. Further, the particle diameter D50Is a value (volume-based median particle diameter) obtained by a laser diffraction method based on an air-flow dispersion method.
Adding 0-0.29% by mass of a particle diameter D to the finely pulverized powder50TiH of less than 10 mu m2The powder was further mixed with 0.05 part by mass of zinc stearate as a lubricant per 100 parts by mass of the fine powder, and then molded in a magnetic field to obtain a molded article. The molding device used is a so-called right-angle magnetic field molding device (transverse magnetic field molding device) in which the magnetic field application direction and the pressing direction are orthogonal to each other.
The obtained compact was held at 1040 ℃ for 4 hours in vacuum and sintered, and then quenched to obtain a sintered magnet. The density of the sintered magnet was 7.5Mg/m3The above. The analysis results of the composition of the obtained sintered magnet are shown in table 3. In Table 3, the following are shownThe respective components of (a) were measured using high-frequency inductively coupled plasma emission spectrometry (ICP-OES). Further, O (oxygen amount) was measured using a gas analyzer based on a gas melting-infrared absorption method; n (nitrogen amount) was measured using a gas analysis apparatus based on a gas melting-heat transfer method; the C (carbon amount) was measured using a gas analyzer based on a combustion-infrared absorption method. The results of the formulae (a) and (B) calculated from the analysis results are shown in table 3. As shown in Table 3, sample Nos. 25 to 27 have substantially the same composition except for the amount of Ti.
[ TABLE 3 ]
The sintered magnet obtained was subjected to a heat treatment of holding at 900 ℃ for 2 hours, then cooling to room temperature, and then holding at 480 ℃ for 2 hours, and then cooling to room temperature. The sintered magnet after heat treatment was machined to prepare samples having a length of 7mm, a width of 7mm and a thickness of 7mm, the samples were magnetized with a pulsed magnetic field of 3.2MA/m, and B of each sample was measured by a B-H plotterrAnd HcJ. The measurement results are shown in Table 4. In addition, for the measurement of BrAnd HcJThe results of analyzing the composition and gas of the R-T-B sintered magnet of (2) are the same as those of the R-T-B sintered magnet material shown in Table 4.
[ TABLE 4 ]
As shown in Table 4, in comparison with sample Nos. 26 and 27 which satisfy both of the formulas (A) and (B), sample No.25 which is a comparative sample not satisfying the formula (A) and which is an example of the present invention, H is higher than HcJGreatly reducing the cost.
< Experimental example 3 >
Using Nd metal, Pr metal, Dy metal, ferroboron, iron-carbon alloy, Ga metal, CuMetal, Al metal, electrolytic Co, Ti metal and electrolytic iron (metal purity is uniform)99% or more) was mixed so as to have the composition shown in table 5, and these raw materials were melted and cast by a belt casting method to obtain a sheet-like raw material alloy having a thickness of 0.2 to 0.4 mm. The obtained flake-like raw material alloy was subjected to hydrogen pulverization, and subjected to dehydrogenation treatment in which it was heated to 550 ℃ in vacuum and cooled to obtain a roughly pulverized powder. Then, 0.04 parts by mass of zinc stearate as a lubricant was added to 100 parts by mass of the obtained coarse pulverized powder, and after mixing, the mixture was dry-pulverized in a nitrogen stream by a jet mill to obtain a particle diameter D50A 4 μm fine powder (alloy powder). In the present experimental example, the oxygen content of the finally obtained sintered magnet was about 0.1 mass% by setting the oxygen concentration in the nitrogen gas at the time of pulverization to 50ppm or less. Further, the particle diameter D50Is a value (volume-based median particle diameter) obtained by a laser diffraction method based on an air-flow dispersion method.
The finely pulverized powder was mixed with zinc stearate as a lubricant in an amount of 0.05 part by mass per 100 parts by mass of the finely pulverized powder, and then molded in a magnetic field to obtain a molded article. The molding device used is a so-called right-angle magnetic field molding device (transverse magnetic field molding device) in which the magnetic field application direction and the pressing direction are orthogonal to each other.
The obtained compact was held at 1100 ℃ for 4 hours in vacuum and sintered, and then quenched to obtain a sintered magnet.
The density of the sintered magnet was 7.5Mg/m3The above. The composition and gas analysis (O (oxygen amount), N (nitrogen amount), and C (carbon amount)) of the obtained sintered magnet are shown in table 5. The components in table 5 were measured by high frequency inductively coupled plasma optical emission spectrometry (ICP-OES). Further, O (oxygen amount) was measured using a gas analyzer based on a gas melting-infrared absorption method; n (nitrogen amount) was measured using a gas analysis apparatus based on a gas melting-heat transfer method; the C (carbon amount) was measured using a gas analyzer based on a combustion-infrared absorption method. The results of the formulae (a) and (B) calculated from the analysis results are shown in table 5. As shown in Table 5, samples No.30 and 31 have the exception thatThe composition was substantially the same except for the amount of B.
[ TABLE 5 ]
For the obtained sintered magnet, heat treatment was performed in which the magnet was kept at 900 ℃ for 2 hours and then cooled to room temperature, and then kept at 500 ℃ for 2 hours and then cooled to room temperature. The sintered magnet after heat treatment was machined to prepare samples having a length of 7mm, a width of 7mm and a thickness of 7mm, the samples were magnetized with a pulsed magnetic field of 3.2MA/m, and B of each sample was measured by a B-H plotterrAnd HcJ. The measurement results are shown in Table 6. In addition, for the measurement of BrAnd HcJAs a result of analyzing the composition and gas of the R-T-B sintered magnet of (1), the composition and gas analysis results of the R-T-B sintered magnet material shown in Table 5 were the same. The measurement results are shown in Table 6.
[ TABLE 6 ]
As shown in Table 6, Δ H of the samples of examples of the present inventioncJPer 0.01B changed only 21kA/m and had a high Br and a high HcJ。
< Experimental example 4 >
Nd metal, Pr metal, Dy metal, ferroboron alloy, iron-carbon alloy, Ga metal, Cu metal, Al metal, electrolytic Co, Ti metal, and electrolytic iron (all metals having a purity of 99% or more) were mixed so as to have the composition shown in Table 7, and these raw materials were melted and cast by a belt casting method to obtain a sheet-like raw material alloy having a thickness of 0.2 to 0.4 mm. The obtained flake-like raw material alloy was subjected to hydrogen pulverization, and subjected to dehydrogenation treatment in which it was heated to 550 ℃ in vacuum and cooled to obtain a roughly pulverized powder. Then, 0.04 parts by mass of zinc stearate as a lubricant was added to 100 parts by mass of the obtained coarse pulverized powder, and after mixing, the mixture was dried in a nitrogen stream by a jet millPulverizing to obtain particle diameter D50A 4 μm fine powder (alloy powder). Further, the particle diameter D50Is a value (volume-based median particle diameter) obtained by a laser diffraction method based on an air-flow dispersion method.
The finely pulverized powder was mixed with zinc stearate as a lubricant in an amount of 0.05 part by mass per 100 parts by mass of the finely pulverized powder, and then molded in a magnetic field to obtain a molded article. The molding device used is a so-called right-angle magnetic field molding device (transverse magnetic field molding device) in which the magnetic field application direction and the pressing direction are orthogonal to each other.
The obtained compact was sintered by holding it at 1090 ℃ for 4 hours in vacuum, and then quenched to obtain a sintered magnet.
The density of the sintered magnet was 7.5Mg/m3The above. The composition and gas analysis (O (oxygen amount), N (nitrogen amount), and C (carbon amount)) of the obtained sintered magnet are shown in table 7. The components in table 7 were measured by high frequency inductively coupled plasma optical emission spectrometry (ICP-OES). Further, O (oxygen amount) was measured using a gas analyzer based on a gas melting-infrared absorption method; n (nitrogen amount) was measured using a gas analysis apparatus based on a gas melting-heat transfer method; the C (carbon amount) was measured using a gas analyzer based on a combustion-infrared absorption method. The results of the formulae (a) and (B) calculated from the analysis results are shown in table 7. As shown in Table 7, samples No.32 and 33 had substantially the same composition except that the amount of B was different.
[ TABLE 7 ]
For the obtained sintered magnet, heat treatment was performed in which the magnet was kept at 900 ℃ for 2 hours and then cooled to room temperature, and then kept at 500 ℃ for 2 hours and then cooled to room temperature. The sintered magnet after heat treatment was machined to prepare samples having a length of 7mm, a width of 7mm and a thickness of 7mm, the samples were magnetized with a pulsed magnetic field of 3.2MA/m, and B of each sample was measured by a B-H plotterrAnd HcJ. The measurement results are shown in Table 8.In addition, for the measurement of BrAnd HcJAs a result of analyzing the composition and gas of the R-T-B sintered magnet of (1), the composition and gas analysis results of the R-T-B sintered magnet material shown in Table 7 were the same. The measurement results are shown in Table 8.
[ TABLE 8 ]
As shown in Table 8, Δ H of the samples of examples of the present inventioncJPer 0.01B changed only 25kA/m with high Br and high HcJ。