JPH0146574B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a permanent magnet alloy and a method for manufacturing the same. More specifically, Cu, Fe and M (M is Nb, Zr, Ta, Hf,
R ₂ Co ₁₇ system (R is at least one rare earth alloy) added with at least one of Ti and V)
This invention relates to a permanent magnet alloy and its manufacturing method. It has been known for a long time that many intermetallic compounds exist between rare earth metals and Co. Then, it was discovered that when the rare earth element R forms an RCo _5- based ferromagnetic compound, it exhibits extremely large magnetocrystalline anisotropy, and this phenomenon led to the development of an RCo ₅ -based alloy as a permanent magnet material. It is progressing.
Among these RCo ₅ alloys, SmCO ₅ in particular
It has a high _I H _c of 30 KOe and a maximum energy product of 25 MGOe, and it can be said that RCo ₅ permanent magnet material is already becoming established as an industrial material. In contrast, R ₂ Co _14- based magnets have emerged as the next generation of rare earth magnets. this
The R ₂ Co ₁₇ alloy has a small ratio of R to Co, is inexpensive, has a high saturation magnetic flux density, and has a high energy product. As a result of the development so far, we have obtained a maximum energy product (BH) _n = 25MGOe, which is equivalent to that of RCo ₅ alloy, in a system in which Cu and Fe are added to R ₂ Co ₁₇ . However, the amount of Cu added necessary for precipitation hardening of RCo ₁₇ is 10 wt% or more, and the upper limit of the residual magnetic velocity density is about 10 KOe. On the other hand, in order to increase Br, it is sufficient to increase the amount of Fe added, but if this amount of Fe added exceeds a certain amount, the coercive force will decrease. Therefore, in order to eliminate such inconvenience,
Zr, Nb, Hf, Ti, V along with Cu and Fe in R ₂ Co ₁₇
Various proposals have been made, including those by the present inventors, for systems with the addition of
JP-A-53-82619, JP-A-53-56623, JP-A-53-132222, etc.). In R ₂ Co ₁₇ like this
Cu, Fe and M (M is Nb, Zr, Ta, Hf, Ti,
In a system containing V, etc.), a material has been found that has an extremely high energy product of (BH) _n =30MGOe, which exceeds that of RCo ₅ alloy. However, in such R ₂ Co ₁₇ alloys, despite the high energy product, the coercive force _I H _c is only 6.
~8KCe only. For this reason, they cannot be used at low permeance operating points, and are limited by material shapes, so the range of application of R ₂ Co ₁₇ alloys has been extremely narrow. On the other hand, the amount of R such as Sm is increased from 24 to 28 wt% to 23
When lowered to about %, even R ₂ (CoCuFeM) ₁₇ series
It has been reported that _I H _c shows a high value of about 20 KOe (Paper NO・XI−2 at the
Forth International Workshop on Rare Earth
−Cobalt Permanent Magnets and Their
Applications, Hakone, Japan・1979). However, in such a system, the squareness of the demagnetization curve is low and the energy product is small, making it impractical for practical use. Therefore, in order to make the R ₂ Co ₁₇ alloy compatible with various applications of rare earth magnets, it is necessary to provide it with even higher coercive force while maintaining the high energy product obtained in the past. The present invention was made in view of the above-mentioned circumstances.Cu, Fe and M (M is Nb, Zr, Ta,
Hf, Ti, V, etc.) has been improved to show an energy product (BH) _n that is comparable to conventional _alloys , and a coercive force _{I H c} that is comparable to RCo ₅ alloys.
The main purpose is to show the following. The present inventors have conducted extensive research for such purposes. By the way, R ₂ Co ₁₇ alloys change into Co ₅ R due to aging.
It is said that the two phases are separated into a Co ₁₇ R _phase and a Co 17 R phase, and are magnetically hardened. Under conditions that exhibit favorable magnetic properties, R ₂ Co ₁₇ alloys are known to have a so-called cell structure as a microstructure (Journal of Applied Physics,
Vo146, 5259, 1975). In this case, the cell structure is
The cell and the cell boundary are clearly distinguished, and as a result of electron beam diffraction, it is said that the inside of the cell has a 17:2 structure, and the cell boundary has a 5:1 structure. On the other hand, it is known that the coercive force of R ₂ Co ₁₇ -based alloys is due to the size of this cell structure. According to previous reports, in a system in which Cu and Fe are added to R ₂ Co ₁₇ , as the aging time becomes longer, the cell size becomes larger and the cell diameter reaches 500 Å.
When the coercive force reaches the maximum, if the aging time is increased further, as the cell diameter increases,
It is said that the coercive force decreases (Journal of
Applied Physics, Vol48, No.3, 1350, 1977). According to the research of the present inventors, R ₂ Co ₁₇
It was found that even in a system in which Cu, Fe, and Zr were added as M, a peak in coercive force was observed when the cell diameter reached approximately 500 Å, and this was reported (Paper No -1
at the Third International Workshop on
Rare Earth−Cobalt Magnets and Their
Applications, University of California San
Diego, 1978). However, according to the inventor's subsequent research,
In a system in which M such as Zr is added to R ₂ Co ₁₇ in addition to Cu and Fe, generally when the center distance between adjacent cells is about 500 Å,
A peak of coercive force is observed, but as the cell diameter further increases and the center distance between cells becomes 700 Å or more, the coercive force increases further, the energy product increases, and the temperature characteristics also change. It was found that the results were good. The present invention has been made based on such knowledge. That is, the permanent magnet alloy of the present invention is
In terms of weight percentage, 20 to 30 wt% of R (R is at least one rare earth metal), 5 to 10 wt% of Cu, and 1
~35wt% Fe and 0.5~6wt% M (M is Nb, Zr,
At least one of Ta, Hf, Ti and V)
and 19 to 73.5 wt% of Co, and has a cell structure as a microstructure, and the intercell distance of this cell structure is 700 Å or more. In this case, the inter-cell distance refers to the distance between the centers of adjacent cells. Therefore,
In the R ₂ Co ₁₇ system in which Cu and Fe are added without adding the above-mentioned M such as Zr, those with such an intercell distance are conventionally known to exhibit coercive force after the peak value. . However, in addition to Cu and Fe,
In the R ₂ Co ₁₇ system added with the above M such as Zr,
With such an inter-cell distance, higher _I H _c and (BH) _n can be obtained, and such a discovery can be said to be something that could not be predicted from conventional knowledge. The permanent magnet alloy of the present invention will be explained in detail below. The composition of the permanent magnet alloy of the present invention, when expressed in weight percentage, is 20 to 30 wt% R (R is the same as above), 5 to 10 wt% Cu, and 1 to 35 wt%
Fe, 0.5-6wt% M (M is the same as above), 19
~73.5wt% Co. In this case, specific examples of R consisting of one or more rare earth metals include:
In addition to Sm, Y, which has similar chemical properties,
La, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho,
Er, Tm, Yb, and Lu can be mentioned, and combinations of one or more of these can be used.
On the other hand, the weight percentage of R is 20 to 30 wt%,
When it is 24 to 28% by weight, the squareness of the demagnetization curve is high and a large (BH) _n is obtained, resulting in more favorable results. Further, M may be Nb, Zr, Ta, Hf, Ti, or V, or a combination of two or more thereof. In addition to these essential component elements, the permanent magnet alloy of the present invention contains one or more other additive elements such as Si, Cr, and Mo as impurities in a range of 3% by weight or less. Good too. The reason why the above-described range of components is limited for the permanent magnet alloy of the present invention is as follows. First, R consisting of one or more rare earth metals is
When it exceeds 30wt%, Br decreases. Also, 20wt%
If it is less than that, high coercive force cannot be obtained. In particular, R
When Sm is used alone or in combination with other rare earth metals, if the amount exceeds 28wt%, Br
At less than 24wt%, a certain degree of coercive force can be obtained, but the squareness of the demagnetization curve decreases,
(BH) _n decreases, which is not desirable. Moreover, when the amount of Fe becomes less than 1 wt%, Br decreases. Increasing the amount of Fe is effective in increasing Br, but Fe
If the amount exceeds 35wt%, _I H _c will decrease. On the other hand, when the amount of Cu exceeds 10 wt%, Br decreases. Furthermore, when the content is less than 5 wt%, _I H _c becomes low. Furthermore, if the content of M, which is one or more of Nb, Zr, Ta, Hf, Ti, and V, is outside the range of 0.5 to 6 wt%, _I H _c and energy product will decrease. The permanent magnet alloy of the present invention having such a composition has a cell structure, and the average distance between the cells in the cell structure (as described above, the distance between the cell centers of adjacent cells) is 700 Å or more. . In this case, if the inter-cell distance is less than 700 Å, _I H _c will only show a value equal to or lower than that in the conventional case. On the other hand, when the intercell distance is 700 Å or more, it becomes 10 KOe or more, and especially 1000 Å or more.
When it reaches Å or more, a high _I H _c of 20 KOe or 30 KOe or more can be obtained under the most favorable conditions. Therefore, it can be used even at low permeance operating points, and there are very few restrictions on material shape. On the other hand, the distance between cells is generally 6000
When the distance is larger than about .ANG., the squareness becomes particularly poor and disadvantages occur, so it is generally preferable that the inter-cell distance is 6000 .ANG. or less. Although the inter-cell distance is as described above, in order to obtain a sufficiently high coercive force, the cell boundary width is preferably about 50 Å to 100 Å or more. Whether or not it has such a cell structure can be easily verified using a transmission electron microscope. In addition, the permanent magnet alloy of the present invention is generally
It exhibits a high coercive force _I H _c of 10 KOe or more, a high energy product, and good temperature characteristics. The permanent magnet alloy of the present invention is generally manufactured as follows. First, each raw material element is mixed to have a predetermined composition as described above, and then this mixture is melted and cast. Next, this master alloy ingot is coarsely ground and then finely ground using a jet mill or the like. This powder is press-molded in a magnetic field of about 5 to 10 KOe, and then the molded body is
Sintering is carried out at a temperature of 1250°C, preferably 1150-1230°C. After this, 1100-1230℃, preferably 1130-1120
Solution treatment is performed at ℃ for about 0.5 to 3 hours. Note that these melting, sintering, solution treatment, etc. can be performed in various atmospheres, but inert, vacuum,
It is preferable to carry out the reaction under a non-oxidizing or reducing atmosphere. After that, the statute of limitations is imposed. Aging is generally preferably carried out under an inert atmosphere or in vacuum. In this case, aging consists of an initial aging performed by holding the material at a predetermined temperature for a predetermined time, and subsequent multi-stage aging or continuous cooling. Initial aging is generally carried out by holding at 700 to 950°C for more than 2 hours. Usually, this holding time may be about 2.5 to 500 hours. The multi-stage aging performed after such initial aging is performed until the temperature drops to at least 600°C, more preferably to about 400°C, for example, 100°C.
It is preferable to hold the temperature at ~200°C for about 0.5 to 20 hours. Also, when performing continuous cooling, the cooling temperature should be 0.2 to 5 ℃ until the temperature drops to at least 600℃, more preferably about 400℃.
It is preferable to cool at a cooling rate of °C/min. In addition, in the manufacturing method of the present invention, after such initial aging, multi-stage aging or continuous aging is performed, which results in a cell distance of 700 Å or more and an extremely high (BH) _n and _I H _c , and a permanent magnet alloy with good temperature characteristics can be obtained. On the other hand, performing isothermal aging at 700 to 950°C, or performing initial aging at 700 to 950°C for 2 hours or less, followed by multi-stage aging or continuous cooling, is not conventional for R ₂ Co ₁₇ alloys. This is a widely used statute of limitations, but when such a statute of limitations is applied, as in the present invention,
It is impossible to obtain an alloy that has an intercell distance of 700 Å or more, exhibits high values of (BH) _n and _I H _c , and has good temperature characteristics. In this way, a magnetically hardened permanent magnet alloy of the present invention is obtained.
As a result of having the above intercell distance, it exhibits a coercive force that far exceeds _{the I} H _c conventionally obtained with the corresponding composition, and also has a high squareness of the demagnetization curve and exhibits an extremely high (BH) _n . As a result, it can be used at low permeance operating points, and there are very few restrictions on shape. Furthermore, irreversible changes are small and exhibit good temperature characteristics. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 Sm25.5wt%, Cu8wt%, Fe15wt%, Zr3wt%
The raw materials were prepared to form an alloy consisting of Co and Co, and the mixture was melted by high frequency induction heating in argon, and then cast in an iron pan to obtain an ingot. This ingot was used as a master alloy and was coarsely ground and then finely ground in a jet mill to obtain a powder with an average particle size of 5 μm. This powder was press-molded in a magnetic field of 10 KOe to obtain a molded body. The molded body thus obtained was sintered in argon at about 1200°C for 1.5 hours, and then at 1200°C.
Solution treatment was performed at approximately ℃. Thereafter, first-stage aging was performed by heating and holding at 850° C. for the time shown in Table 1 below in argon, and then multi-stage aging was performed. In this case, multi-stage aging is performed at 700℃ for 1 hour, 600℃ for 1 hour,
This was carried out by holding at 500°C for 2 hours and at 400°C for 12 hours. When the average intercell distance (distance between cell centers) of the five types of permanent magnet alloys magnetically hardened in this way was measured using a transmission electron microscope, the values shown in Table 1 below were obtained. . Furthermore, when the coercive force _I H _c and the maximum energy product (BH) _n were measured for each permanent magnet alloy, the results shown in Table 1 below were obtained. Furthermore, irreversible changes were measured for each permanent magnet alloy. Irreversible changes were measured at a permeance of 1 by heating from room temperature to 200°C, then returning to room temperature, and measuring the change in magnetization (%). The results are also listed in Table 1.

[Table] From the results in Table 1, it can be seen that according to the present invention, the inter-cell distance is
It can be seen that when the thickness is 700 Å or more, _I H _c , (BH) _n , and irreversible change (temperature characteristics) are all significantly improved. Example 2 Each raw material was mixed to form an alloy with the composition of the 10 types shown in Table 2 below, and this mixture was melted by high-frequency induction heating in argon, and then cast in an iron pan to form the 10 types of alloy. Obtained an ingot. Each of these was used as a master alloy, and after coarsely pulverized, finely pulverized using a jet mill to obtain powder with an average particle size of 5 μm. This powder was press-molded in a magnetic field of 10 KOe to obtain a molded body. Each molded body was heated to 1150 to 1230 in argon.
Sinter for 1-2 hours at a temperature of 1130-
Solution treatment was performed at 1200°C. Next, first-stage aging was performed in argon at 850°C for 5 hours, and then multi-stage aging was performed up to 400°C using the same temperature profile as in Example I. As in Example 1, for the 10 types of permanent magnet alloys magnetically hardened in this way, the intercell distance _I
H _c and (BH) _n were measured. The results are shown in Table 2.

[Table] From the results in Table 2, permanent magnet alloys No. 6 to 15 belonging to the present invention have extremely high _I H _c values as a result of having intercell distances of 700 Å or more, and that value is higher than that of conventional RCo. It can be seen that this is comparable to that of the _5- series alloy, and in addition, it exhibits an extremely high (BH) _n value. Incidentally, when the irreversible change (%) of these permanent magnet alloys was measured in the same manner as in Example 1, all of them showed values of 2% or less, and it was confirmed that they exhibited good temperature characteristics. Example 3 Sm25.5wt%, Cu6wt%, Fe12wt%, Zr2.5wt
% and the balance was Co, casting, crushing, molding, sintering, and solution treatment were performed in the same manner as in Example 2. Next, after an initial aging at 850°C for 5 hours in argon, each permanent magnet alloy was cooled at a cooling rate of 1°C/min to the temperatures shown in Table 3 below, and thus magnetically hardened. _I H _c was measured for . The results are also listed in Table 3.

[Table] From the results in Table 3, to obtain a preferable _I H _c ,
It can be seen that after the first stage aging, it is necessary to perform multistage aging or continuous cooling to approximately 600°C. Note that the average intercell distance of these samples Nos. 18 to 21 was about 1500 Å. Example 4 Sm25.5wt%, Cu8wt%, Fe14wt%, Zr3wt%
The alloy consisting of Fe and the remainder was cast, pulverized, molded, sintered and solution treated in the same manner as in Example 2, and after aging at 850°C for 25 hours in argon, the alloy was exactly the same as in Example 1. Multi-stage aging was performed up to 400℃. The average intercell distance of the obtained permanent magnet alloy No. 22 is
1700 Å, _I H _c = 27 KOe, (BH) _n =
Obtained 27.2 MGOe.

Claims (1)

[Claims] 1. 20 to 30 wt% of R (R is at least one rare earth metal) and 5 to 10 wt% of Cu;
1 to 35 wt% Fe and 0.5 to 6 wt% M (M is Nb,
At least one of Zr, Ta, Hf, Ti and V
A permanent magnet alloy containing 19 to 73.5 wt% of Co and having a cell structure as a microstructure, characterized in that the distance between the cells of the cell structure is 700 Å or more. 2. In terms of weight percentage, 20 to 30 wt% of R (R is at least one rare earth metal) and 5 to 10 wt% of Cu;
1 to 35 wt% Fe and 0.5 to 6 wt% M (M is Nb,
At least one of Zr, Ta, Hf, Ti and V
seeds) and 19 to 73.5 wt% Co.
After sintering and solution treatment, the product is held at 700 to 950°C for more than 2 hours, and then subjected to multi-stage aging to 600°C or lower, or continuously cooled, with a weight percentage of 20 to 30 wt%. (R is the same as above), 5-10wt% Cu, and 1-35wt% Fe.
, 0.5~6wt% M (M is the same as above), and 19~
A method for producing a permanent magnet alloy containing 73.5wt% Co and having a microstructure with a cell structure in which the distance between cells is 700 Å or more.