JPS6247455A - Permanent magnet material having high performance - Google Patents

Abstract

PURPOSE:To provide ferromagnetism to an Fe-B-R type permanent magnet material by making the C and O2 contents in the material as low as possible, forming tetragonal principal phases of a specified grain size having body- centered cubic lattices of a specified uniform thickness in the surface part and holding a nonmagnetic phase between the principal phases. CONSTITUTION:The composition of a permanent magnet material is composed of 12-15 atomic% R (R is Nd and/or Pr and <=1 atomic% heavy rare earth element may be substituted for part of Nd and/or Pr), 5.5-8 atomic% B, <2,000ppm O2, <800ppm C and the balance Fe with inevitable impurities. The tetragonal principal phases of <=10mum grain size having body-centered cubic lattices of 5-500Angstrom uniform thickness are formed in the surface part of the material, and a nonmagnetic phase consisting of an R-rich metallic phase, a B-rich metallic phase and an oxide phase is held between the principal phases. The resulting permanent magnet material has sich high performande as >=40 MGO8 (BH)max.

Description

Detailed Description of the Invention Field of Application This invention relates to the improvement of Fa-B-R permanent magnet materials, including high-performance fJIFe B with a maximum energy product of (BH)maX≧45HGOe.
This invention relates to R-based permanent magnet materials.

Background technology Current representative permanent! 1nEI materials are alnico, hard ferrite and rare earth cobalt la'EJ.

Among these, rare earth cobalt magnets have extremely excellent magnetic properties and are used for a variety of purposes, but their main components, Sm and Co, are both scarce and expensive, and will continue to be used for a long time. It is difficult to stably supply large amounts of it. Therefore, there has been a strong desire for a permanent magnet material that has excellent magnetic properties, is inexpensive, and is composed of constituent elements that are abundant in resources and can be stably supplied in the future.

The present applicant previously proposed an FB-B-R type permanent magnet (R is at least one rare earth element including Y) as a new high-performance permanent magnet that does not contain expensive Sm (Japanese Patent Application Laid-Open No. 59-1993). -46008, JP-A-59-64733,
Japanese Patent Publication No. 1983. No.-89401, JP-A-59-13210
No. 4).

This permanent magnet uses resource-rich light rare earths mainly positive and circular as R, and has 15MGO with Fe as the main component.
It is an excellent permanent magnet that exhibits an extremely high energy product of 8 or more.

The composition that gives this FB-BR permanent 1a5 even higher magnetic properties is R (R is m, Pr, ki).

) 1o, at least one of Tb, or in addition, i
.

Ce, Sm, CcJ, Er, Eu, Dingm, Y
consisting of at least one of b, Li, Y)10
．． 0 atom% to 30 atom%, B2 atom% to 28 atom%, F
We have proposed a permanent magnet material whose main component is 60 atomic % to 83 atomic % e and whose main phase is tetragonal. In terms of crystal structure, this permanent magnet has a R2F1114B tetragonal magnetic phase of 5
0vo1% or more, non-magnetic phase consisting of R-rich metal phase, B-rich metal phase and R2O:1 phase consists of 50vo1% or less, 13r is 10.5kG or more, HC is 10ko
It is an excellent permanent magnet that exhibits an extremely high energy product of more than e and 25MGOs, and (BH)maX is 4
0) Reach IGOe.

In this way, permanent magnets have a high performance that cannot be compared with conventional magnets, but in order to meet the demands for smaller size and higher performance in today's equipment,
In general, a high performance permanent IA5 material with (BH)max of 408 GOe or more is required.

Purpose of the Invention The present invention aims to improve the magnetic properties of Fa-B-R permanent magnet materials, particularly the maximum energy product, so that (BHmax≧40) high performance of IGOe can be obtained. It is aimed at FB-BR-based permanent magnet materials.

Structure and Effects of the Invention In order to improve the magnetic properties of FaBR permanent magnet materials, especially (BH)ma: Regarding the correlation, especially Fe B I'! As a result of various studies on the J sintered Ia stone body, the specific phase relationship between the tetragonal magnetic phase having a specific surface layer and the non-magnetic phase interposed therebetween is as follows:
BH) max, etc., were found to be particularly significantly involved.

That is, in the FeBNd sintered magnet, the presence of a body-centered cubic phase in the surface layer of the R2Fe+4B tetragonal magnetic phase is essential for high coercive force. Furthermore, if the amount of non-magnetic phase consisting of R-rich metal phase, B-rich metal phase and R2O3 phase increases, the Br decreases due to HC, so it is thought that the absence of non-magnetic phase is effective. According to the results of an investigation using an electron microscope, this nonmagnetic phase has an important effect on the generation of coercive force at the grain boundaries of the sintered magnet, and is also greatly involved in the formation of grain boundaries.
In the B-Nd sintered magnet body, there is no non-magnetic phase C
If this occurs, FB will precipitate on the sintered magnet body, resulting in a rapid decrease in coercive force. However, if the specific phase structure of an R2F814B tetragonal magnetic phase having a surface layer of a body-centered cubic phase with a specific thickness and a nonmagnetic phase consisting of an R-rich metal phase, a B-rich metal phase, and an R2O3 phase is satisfied, It has been found that the magnetic properties of the sintered magnet body, especially the properties in which (BH)max exceeds 458 GOe, can be obtained.

In addition, we found that reducing the amount of oxygen contained within a specific range of Fe, B, and R is effective in improving the magnet properties, and reducing the amount of C improves the corrosion resistance of the magnet. Because it promotes the growth of crystal grains during sintering, there is a problem that it causes property deterioration.In response to this problem, adding boride is effective in suppressing the growth of crystal grains during sintering. Fa.

It has been found that when a specific range of B, R, I compounds e''e and a specific phase relationship between the magnetic phase and the non-magnetic phase are satisfied, the maximum value of (BH)max reaches 50 MGOs or more.

That is, this invention provides R12,0 at% to 15.0 at% to 15.0 at% (
R is M or one or two of the phylums, or a part thereof with 1 atomic % or less of DV, Di, Gd, Ho,
At least one of the heavy rarefied elements Er, chlorine, and yb
), B5.5 atomic% to 8.0 atomic%, 0220001) l) m or less, C800 ppm or less, as necessary, TL, Zr, HP, V, Nb,
Ta, Mo, W.

The grain size is 10.2 atomic % or less of at least one kind of N, the balance is Fθ and unavoidable impurities, and the surface portion has a body-centered cubic phase with a uniform thickness of 5 Å to 500 Å. A main phase consisting of tetragonal crystals of OIJm or less, an R-rich metal phase between the main phases, and B
It is a high-performance permanent magnetic material characterized by having a non-magnetic phase consisting of a rich metal phase and an oxide phase, and having a maximum energy product (BHmax≧45) of IGOs.

In this invention, R12.5 atomic% to 13.5 atomic% (R can be substituted with one or two moieties or groups, or a part thereof can be replaced with 1 atomic% or less of a heavy rare upper element), 36 .0 atomic%~7
．． 5 at.
Grain size 8 with body-centered cubic phase of uniform thickness of Å ~ 400
．． When a specific phase relationship is satisfied in which a main phase consisting of a tetragonal crystal with a term of 0 or less and a nonmagnetic phase consisting of an R-rich metal phase, a B-rich metal phase, and an oxide phase are interposed between the main phases, the resulting permanent magnet material ( B H) max is 468 GOa or more, maximum 5
2) Reach IGOa or higher.

Further, in a preferred composition range of the permanent magnet material 1 according to the present invention, a part of Fe is 2 atomic % or less of TFI ZY1'
r'+f, V, positive, Ta, Mo, W,
By replacing Aft with at least these species, the obtained permanent magnet material (BI-()maX is 46HG
Oe or more, reaching a maximum of 52 MGOe or more, and an excellent coercive force can be obtained.

Also, TiB2, E3N, ZyBz, ZrBtz
, HfB2, VB2, NbB, NbB2, TaB
, TaB2, CrB2, MoB, MOB2, t'b
0.05 at.% to 3.0 at.%, preferably 0.10 at.% of at least one type of boride such as 2 B, WB, W2B, etc.
Addition of from atomic % to 0.50 atomic % can suppress crystal grain growth during sintering and improve magnetic properties.

Reasons for limiting the composition of permanent magnets The rare earth element R of the permanent magnet material of this invention is ceramic.

At least one type of phylum, noura, or even Dy.

It can be replaced with at least one of the heavy rarefied elements Tb, Gd, Ho, Er, Tb, and Yb.

Also, normally one type of R is sufficient, but in practice two types are sufficient.
A mixture of more than one species (Mitushmetal, Didim, etc.) can be used for reasons such as availability.

Note that this R does not have to be a pure rare earth element, and may contain impurities that are unavoidable in production within an industrially available range.

R is an essential element in this Fe-BR permanent magnet IJI, and if it is less than 12 atomic %, the crystal MA structure will be α
-High magnetic properties due to the same cubic crystal structure as iron
In particular, if a high coercive force cannot be obtained and the content exceeds 15 at%, the R-rich nonmagnetic phase increases, and the coercive force remains at 10 kos or more, but the residual magnetic flux density Br decreases, resulting in a permanent magnet with excellent characteristics. is not obtained.

Therefore, the rare earth element is in the range of 12 atomic % to 15 atomic %.

B is an essential element in Fe-BR permanent magnets, and if it is less than 5.5 at%, it will cause a decrease in the coercive force and squareness of the sintered magnet, and if it exceeds 8.0 at%. , the B-rich nonmagnetic phase increases, the residual magnetic flux density Br decreases,
(BH) maX decreases and an excellent permanent magnet cannot be obtained. Therefore, B is 5.5 atomic % to 8. O[Child% range.

Oxygen contained in the water-based permanent magnet material is undesirable because it combines with the rare earth element that is most easily oxidized to form a rare earth oxide, which remains in the permanent magnet as an oxide R2O3.
□However, if it exceeds 2000 ppm, Br, Hc and (B
H) Since both maX decreases, the amount of 02 is 2000pp
m or less.

Moreover, if the content of carbon atoms exceeds 800 ppm, it is not preferable because it causes dull Hc and deterioration of squareness, making it impossible to obtain high magnetic properties.

Fe is an essential element in the above-mentioned permanent magnet material, and is the remaining content of other essential elements and addition 7] [1 element.

In the phase structure of the permanent magnet material according to the present invention, when a body-centered cubic phase with a uniform thickness of 5 Å to 500 A is formed on the surface of the main tetragonal phase, movement of the stone wall within the body-centered cubic phase is suppressed. , the coercive force is improved, but if there is no body-centered cubic phase in the structure, only an extremely low coercive force of about 0.2 to 0.3 kOe can be obtained, and a uniform thickness of at least 5 A is required. In order to obtain a high coercive force, a thickness of 808 to 4008 is preferable, and if it exceeds 500 A, the coercive force decreases again, which is not preferable.

Furthermore, if the thickness of the body-centered cubic product is non-uniform or if crystal defects, precipitates, or inclusions are present near the body-centered cubic phase, the magnetic properties will deteriorate dramatically. In addition, the non-magnetic phase consisting of the R-rich metal phase, B-rich metal phase and oxides interposed between the main phases forms a liquid phase when sintering the molded body of the water-based alloy powder, and the sintered body becomes high. It is effective for densification, and more particularly for promoting the formation of body-centered cubic products during aging treatment after sintering.

Further, it is preferable that the quantitative ratio of the R2F1314 B tetragonal magnetic phase and the non-magnetic phase consisting of the R-rich metal phase, the B-rich metal phase and the oxide is set to magnetic phase/non-magnetic phase = 15 to 300. This is because when the quantity ratio is less than 15, f3r decreases and the characteristic of (BH)max≧45HGOa cannot be obtained, and when it exceeds 300, it becomes very difficult to obtain a sintered magnet body, and This is because Fe becomes easier to sell and causes deterioration of magnetic properties.

Further, in the permanent magnet material according to the present invention, a part of Fe is replaced by 2 atomic % or less of Tj, Zr, Hf, V, N.
b.

By substituting with at least one of Ta, Mo, W, and M, an excellent coercive force can be obtained, but if the amount of substitution exceeds 2 atomic %, it is undesirable because it causes a decrease in B' (C).

0.05 atomic % to 3.0 at least one type of boride
When Ti is contained in atomic%, the growth of crystal grains during sintering of the magnet body can be suppressed when the 02 index is 2000 ppm or less.
B2, BN, ZrB2.2JB12, HfBz,
V B2 , NbB, NbB2 , rag, TaB2
, CrB2, MoB, MOB2, Mo2 BlWB
It is also good to add at least one type of boride such as , W2B, etc.

If m of this boride is less than 0.05 at%, the effect of suppressing crystal grain growth during sintering of the magnet body, that is, the effect of making the product finer, cannot be obtained, and if it exceeds 3.0 at%, The above effects are saturated at 3r.

(BH)max decreases rapidly, so 0.05 at%
~3.0 at%.

Further, in the permanent magnet material according to the present invention, replacing a portion of Fe with 15 atomic % or less can improve the temperature characteristics without impairing the magnetic properties of the resulting magnet.

The permanent IA stone material according to the present invention is manufactured using an alloy powder obtained by an ingot crushing method or a Ca reduction diffusion method as a raw material.
In particular, it is necessary to reduce ozffi as much as possible, and permanent rJ
High performance is ensured by storing and manufacturing i1 stone materials in an inert atmosphere to prevent oxidation during the entire manufacturing process.

Further, the permanent magnet of the present invention can be press-molded in a magnetic field to obtain a magnetically anisotropic magnet, and can be press-molded in a non-magnetic field to obtain a magnetically isotropic magnet.

Example u version Electrolytic iron with a purity of 99.9%, ferroboron alloy, and ceramic metal with a purity of 99.7% or more were used as starting materials. After mixing these, they were high-frequency melted in an Ar atmosphere, and then water-cooled with copper. Cast into a mold, 13. ONd 6.5 B Bo,
A tohg casting rule with a composition of 5Fe was obtained.

Thereafter, this ingot was coarsely pulverized in an Ar atmosphere using a stamp mill, and then finely pulverized using a ball mill to obtain powder with an average particle size of 1.674 m.

The obtained NdB-Fe alloy powder was stored so as not to oxidize, and then each fine powder was inserted into a mold in an Ar atmosphere, oriented in a magnetic field of 20.0 kOe, and perpendicular to the magnetic field. Molding was carried out at a pressure of 1.5 tJ.

The molded body with dimensions of 10 mm x 15 + y + m x 20 tnm was sintered at 1100°C for 1 hour in an Ar atmosphere, and then roughly sintered in Ar at 800°C for 1.5 hours and at 6008C for 1.5 hours. It was subjected to two-stage aging treatment and turned into a magnet.

The composition, magnetic properties, and corrosion resistance of the obtained sintered magnet body were measured, and the results are shown in Table 1. Corrosion resistance is at a temperature of 70℃
An accelerated test was conducted at a humidity of 95% x lo 00 hours, and the weight gain by oxidation (ppm) was evaluated.

Further, FIG. 1 shows an electron micrograph (magnification: 100,000 times) of the structure of the permanent magnet material according to the present invention. In the photo, (
1) is the main phase, (2) is the body-centered cubic product, and (3) is the M-rich phase.

For comparison, electrolytic iron with a purity of 99.9%, ferroboron alloy, and M metal with a purity of 99.7% or more were used as starting materials. After blending these, they were high-frequency melted in an Ar atmosphere, and then water-cooled copper Cast in a mold, 16.5Nd9, OB
1q of 10k (IU) of composition 74.5Fe was collected.

Thereafter, this ingot was coarsely ground in the atmosphere using a stamp mill, and then finely ground using a ball mill, with an average particle size of 1.
A fine powder of 8 μm was removed.

After that, each fine powder was inserted into a mold in the atmosphere, and the
koe oriented in the magnetic field and perpendicular to the magnetic field, 1.5j
It was molded at a pressure of 4.

The obtained molded body with dimensions of 10 mm x 15 mm x 20+r+m was sintered at 1120°C for 2 hours in an Ar atmosphere, and then sintered at 800°C for 1.5 hours and at 600°C for 1.5 hours. After 5 hours of two-stage aging treatment, F! 1
It became 15.

The composition, magnetic properties, and corrosion resistance of the obtained sintered magnet body were measured, and the results are shown in Table 1. Corrosion resistance is at a temperature of 70'C
An accelerated test of x humidity 95% x looo time was conducted and evaluation was made in terms of oxidation weight gain (ppm).

Further, FIG. 2 shows an electron micrograph (magnification: 50,000 i'8) of the structure of the comparative permanent magnet material.

As starting materials, electrolytic iron with a purity of 99.9%, ferroboron alloy, ceramic metal with a purity of 99.7% or more, metals, and ferroniobium are used as starting materials. After blending these, high-frequency melted and then cast into a water-cooled copper mold, 13.0
NdO, 25Dv 6.5F30.25 N080.0
An iokg ingot having a composition of Fe was obtained.

Thereafter, this ingot was coarsely pulverized by a stamp mill in a high-purity Ar atmosphere with a purity of 99.999%, and then finely pulverized by a ball mill to obtain a fine powder with an average particle size of 1.3 μm.

The obtained Nd Oy B -Nb Fe alloy powder was stored so as not to be oxidized, and then each fine powder was inserted into a mold in an Ar atmosphere, oriented in a magnetic field of 20.0 kOe, and then perpendicular to the magnetic field. , 1.5 iJ pressure.

The obtained compact with dimensions of 10 mm x 15 mm x 20 mm was sintered at 1100°C for 2 hours in an Ar atmosphere, and then sintered at 800°C for 2 hours and 600°C in Ar.
°Q, Two-stage aging treatment for 2 hours was performed to form a magnet.

The composition of the obtained sintered magnet body, f! The stone properties and corrosion resistance were measured and the results are shown in Table 2. Corrosion resistance at temperature 70
'CX humidity 95% x 1000 hours acceleration test 1 ~ was conducted and oxidation gain ffi (ppm) was evaluated.

The microscopic structure of the obtained sintered stone body was similar to that in FIG.

Next, for comparison, an ingot of the same composition produced under the above conditions was subjected to fine pulverization, molding, sintering and two aging treatments under exactly the same conditions except that it was pulverized in a 99% Ar atmosphere, and magnetized. The composition, 11-stone properties, and corrosion resistance of the sintered magnet bodies were measured, and the results are shown in Table 2.

Table 1 Table 2

[Brief explanation of the drawing]

FIG. 1 is an electron micrograph (magnification: 100,000 times) of the permanent 1a5 material according to the present invention, and FIG. 2 is an electron micrograph (magnification: 50,000 times) of a comparative permanent magnet material. Applicant: Sumitomo Special Metals Co., Ltd. 1' 1・dll

Claims (1)

[Claims] 1 R12.0 atomic % to 15.0 atomic % (R is Nd or P
one or two types of r, or a part thereof can be substituted with 1 at% or less of a heavy rare upper element), B5.5 at% to 8.0 at%, O_22000 ppm or less, C800 ppm or less, the balance being Fe and A main phase consisting of tetragonal crystals with a grain size of 10.0 μm or less, which is composed of unavoidable impurities and has a body-centered cubic phase with a uniform thickness of 5 Å to 500 Å on the surface, and an R-rich metal phase and a B-rich metal phase between the main phases. A high-performance permanent magnetic material characterized by having a non-magnetic phase consisting of an oxide phase and an oxide phase. 2 R12.0 at% to 15.0 at% (R is Nd or P
One or two types of r, or a part thereof can be substituted with 1 atomic % or less of a heavy rare element), B5.5 atomic % to 8.0 atomic %, Ti, Zr, Hf, V, Nb , Ta, Mo, W, and Al at least 2 atomic %, O_22000 ppm or less, C800 ppm or less, and the balance is Fe and unavoidable impurities, and has a body-centered cubic phase with a uniform thickness of 5 Å to 500 Å on the surface. A high-performance permanent magnet material characterized by having a main phase consisting of tetragonal crystals having a particle size of 10.0 μm or less, and a nonmagnetic phase consisting of an R-rich metal phase, a B-rich metal phase, and an oxide phase between the main phases.