JPH0248616B2 - - Google Patents

Description

[Detailed Description of the Invention] Background Technical Field of the Invention The present invention relates to R ₂ Co _17- based Cu substitution precipitation hardening mainly consisting of an intermetallic compound of Co and a rare earth element R consisting of one or more of the cerium group and the yttrium group. The present invention relates to a method for heat treatment of permanent magnet materials of molds. Prior art and its problems By weight percentage, 22 to 28% of R (R is one or more rare earth elements), Co, Cu, one or more of Fe, Ni, Mn and Cr, Zr, Ti, Hf, Nb,
A rare earth cobalt based R ₂ Co ₁₇ based Cu substitution precipitation hardening permanent magnet having a composition consisting of at least one of V and Ta is known. This magnet has large residual magnetic flux density (Br), coercive force (bHc, iHc), and energy product (B・H)
It is a permanent magnet with a large max, a high Kyrie temperature, and excellent temperature characteristics. In order to manufacture such permanent magnets, a compound is prepared by a known reduction-diffusion method or dissolution method, and then subjected to solution treatment, aging treatment, pulverization, and magnetic field orientation to form a rubber compound. or plastic resin as a binder to make powder molded magnets, or after crushing the compound and molding it in a magnetic field,
After that, sintering and solution treatment are performed, followed by aging treatment to form a sintered magnet. In such cases, the aging treatment of R ₂ Co ₁₇ -based Cu-substituted magnets uses spinodal decomposition to disperse and precipitate fine precipitates in the matrix, and controls this phase separation to increase the holding force. This is a heat treatment for Since the state of this precipitation and phase separation greatly influences the performance of the magnet, performing this aging treatment under optimal conditions is an extremely important point in manufacturing. Conventionally, aging treatments for R ₂ Co ₁₇ -based Cu substitution precipitation hardening magnets include multi-stage aging from 700 to 900°C to around 400°C (Japanese Patent Application Laid-open No. 133106/1983); A method of slowly cooling from a temperature of 10°C to around 400°C is known (Japanese Patent Application Laid-open No. 106624/1983). However, with these conventional aging treatments, it is still difficult to obtain sufficiently satisfactory magnetic properties in terms of coercive force, residual magnetic flux density, energy product, hysteresis curve squareness, magnetization properties, etc. In particular, it is desired to improve the magnetic properties in low-cost practical magnet material compositions with low Cu content of 10wt% or less, especially 8wt% or less, and high Fe content of 6wt% or more, especially 10wt% or more. ing. In other words, to explain more specifically, with these practical magnet material compositions with low Cu content and high Fe content, by applying conventionally known aging treatment, approximately 12KG of Br can be obtained, and more than 30MGOe (B・H) max
Despite the expected value, the squareness is poor;
The expected (B・H) max value cannot be obtained. In this case, for a composition with a Cu content slightly less than 10 wt%,
Although it is possible to obtain a (B・H) max value that is only about 1 to 2 MGOe smaller than the desired (B・H) max value, conventional aging treatment cannot achieve an increase in the energy product of 1 to 2 MGOe. This is not possible, and this poses a major practical problem. In addition, when the amount of Cu is reduced to about 2 to 3 wt%, Br is also extremely reduced by the conventional aging treatment method, and a magnet that can withstand practical use cannot be realized. Furthermore, the conventional aging treatment of rare earth cobalt-based materials requires a long holding time at the aging start temperature and end temperature, and has the disadvantage that the aging time is long. In addition, in the conventional aging treatment of rare earth cobalt-based materials, attention is focused only on the method of controlling cooling, and there is no example of repeated heating and cooling multiple times. Furthermore, JP-A-57-161044 discloses that primary sintering and secondary sintering are performed, and after isothermal treatment, cooling is performed from a higher temperature. However, this method is extremely complicated in that sintering must be performed twice, which increases the cost of the product. Also, the squareness ratio of the demagnetization curve is insufficient. Furthermore, the aging treatment method is different from the aging treatment method of the present invention in that after isothermal treatment at a low temperature, the next aging treatment is performed at a raised temperature. Purpose of the Invention The present invention has been made in view of the above circumstances, and its main purpose is to improve magnetic properties such as coercive force, residual magnetic flux density, energy product, squareness ratio, and magnetization characteristics with high Fe. R ₂ Co ₁₇ -based Cu substitution significantly improves the amount and low Cu content compared to conventional aging treatment, resulting in a practical magnet with magnetic properties that are sufficiently satisfactory for practical use, and also shortens the aging treatment time. An object of the present invention is to provide a method for heat treatment of molded permanent magnet materials. These objects are achieved by the invention described below. That is, the present invention includes, in weight percentage, 22 to 28% R (R is one or more rare earth elements), 2 to 10% Cu, 6 to 35% T (T is Fe,
one or more of Ni, Mn and Cr), 0.5 to 6%
M (M is a combination of Zr and/or Hf and one or more of Ti, Nb, V and Ta), the balance being Co
After sintering and solution treatment of a rare earth cobalt-based intermetallic compound having a composition mainly consisting of This is a heat treatment method for a permanent magnet material, which is characterized by repeating heat treatment for cooling at a high speed two or more times. Note that the permanent magnet manufacturing method described in Japanese Patent Application Laid-Open No. 58-219704, which is an earlier application of the present application, involves multi-stage aging of the same type as the present invention, but the R ₂ Co _17- based material is / or Hf as the only constituent element, and in addition to Zr and/or Hf, Ti,
This is different from the present invention, which contains one or more of Nb, V, and Ta as an essential component. Furthermore, JP-A-58-25403 discloses a heat treatment method in which an R ₂ Co ₁₇ alloy is heated to 800 to 900°C, cooled to 400°C or less, and this annealing is repeated at least twice. . However, this method has a drawback that the squareness ratio is low because the cooling rate during repeated annealing is as high as 2° C./sec, that is, 120° C./min. Specific Configuration of the Invention The specific configuration of the present invention will be described in detail below. In the heat treatment method of the present invention, the sintered alloy is subjected to solution treatment prior to multiple heat treatments for aging. The solution treatment may be performed either after sintering or at the same time as solution treatment and sintering. Sintering and solution treatment are preferably performed at 1000°C or higher. This is because the squareness of the hysteresis curve and the coercive force decrease below 1000°C. In such cases, solution treatment is typically carried out at 1000°C.
It is applied at ~1200℃ for about 0.5 to 10 hours. After solution treatment, the material is rapidly cooled. This rapid cooling is generally performed at a cooling temperature of about 1 to 300°C/min. Then, the first rapid cooling
The cooling may be carried out to any temperature below the cooling start temperature of 750 to 950°C. Thereafter, heating is performed to a cooling start temperature for a predetermined heat treatment, if necessary, and then heat treatment is performed a plurality of times. In other words, each heat treatment performed multiple times is
It consists of a cooling process from a cooling start temperature of 750 to 950°C to a cooling end temperature of 700°C or less. By repeating such heat treatment two or more times, the desired effects of the present invention can be achieved. In this case, the number of repetitions may be any number of times as long as it is two or more times, but from the viewpoint of shortening the aging treatment time, it is preferably 2 to 4 times. The cooling start temperature each time may be different from each other, but is preferably 750 to 950°C, preferably 780 to 950°C.
It is 920℃. If the cooling start temperature is less than 750°C, precipitation hardening will be insufficient, and if it exceeds 950°C, the precipitated particles will become coarse and the coercive force will decrease, which is unsuitable. The cooling end temperature for each round may be different, but is 700°C or less. If the cooling end temperature exceeds 700°C, the precipitated particles may become coarse, or precipitation hardening may become insufficient, resulting in a decrease in coercive force, which is not preferable. In this case, when the cooling end temperature is set in the range from 600° C. to room temperature, particularly in the range from 500° C. to room temperature, more favorable results can be obtained in terms of improved magnetic properties. Note that such improvement in characteristics becomes greater as the cooling end temperature is lowered, but the effect remains almost unchanged below 400°C. The cooling rate each time is 0.05 to 15°C/min, more preferably 2 to 10°C/min. In this case, the cooling profile may be multistage cooling in which the temperature is temporarily maintained, or continuous cooling in which the cooling rate is changed midway as necessary. However, in order to shorten the aging treatment time, continuous cooling is preferable, and it is particularly preferable to reduce the cooling rate in the final stage compared to the initial stage. The optimum conditions for the cooling profile vary depending on the composition, etc.
It can be easily determined through experiments. Furthermore, although the heating profile for each heat treatment time is arbitrary, it is usually about 2 to 10°C/min. Note that it is preferable to provide a holding time at the cooling start temperature. Holding time is usually 5 minutes ~
The time is about 20 hours, but preferably 10 minutes to 6 hours. This holding time is determined empirically based on a combination of the number of repetitions, cooling rate, etc. On the other hand, at the cooling end temperature, it is not necessarily necessary to provide a holding time. The composition of the permanent magnet material subjected to such heat treatment multiple times is as described above. In this case, the rare earth element R contained in the range of 22 to 28 wt% may be one or more of cerium and yttrium, but it is particularly preferable to include samarium or cerium. Moreover, the content of Cu is 2 to 10 wt%. Otherwise, the effectiveness of the present invention will be reduced. In this case, the Cu content is 2.5 to 8 wt%, especially 3
When it becomes ~7.5 wt%, the rate of increase in magnetic properties compared to conventional aging treatment becomes extremely large. As a result, a magnet with extremely good magnetic properties is realized. Furthermore, T of one or more of Fe, Ni, Mn, and Cr is contained in an amount of 6 to 35 wt%. If T has a content value other than this, the effectiveness of the present invention will be reduced. In this case, T contains Fe as an essential element, and if necessary, contains one or more of Ni, Mn, and Cr to obtain more preferable results. When the Fe content is 10 to 25 wt%, particularly 14 to 25 wt%, the rate of increase in magnetic properties compared to conventional aging treatment becomes extremely large, and a magnet with extremely good magnetic properties is realized. In addition, the permanent magnet material in the present invention includes:
Zr and/or Hf with Ti, Nb, V and Ta
M is a combination with at least one or more of the following.
is contained in an amount of 0.5 to 6 wt%. If the M content is higher than this, the magnetic properties will deteriorate. In addition to Zr and/or Hf, at least one of Ti, Nb, V and Ta
By containing more than 1 species, a magnet with a large residual magnetic flux density (Br), coercive force (bHc, iHc), large energy product ((B・H) max), high Curie temperature, and excellent temperature characteristics can be created. It becomes possible. In order to produce a permanent magnet using the heat treatment method of the present invention, the compound is pulverized, subjected to magnetic field molding, then subjected to sintering and solution treatment, rapidly cooled, and then subjected to multiple heat treatments of the present invention. administer. This forms a sintered magnet. Specific Effects of the Invention According to the present invention, magnetic properties such as coercive force, residual magnetic flux density, energy product, squareness ratio, and magnetization properties are improved compared to when conventional aging treatment is performed. That is, in a practical magnet material composition with a low Cu content of 10 wt% or less and a high Fe content, magnetic properties that are sufficiently satisfactory for practical use can be obtained. In this case, in a Cu content range relatively close to 10 wt%, for example 4 to 10 wt%, especially 4 to 8 wt%, squareness can be improved while keeping Br at the same level or higher compared to conventional aging treatment. , the coercive force improves, so
The desired (B·H)max value was obtained, and the characteristics were sufficiently satisfactory for practical use. In addition, at lower Cu compositions, such as 2 to 4 wt%, especially 2.5 to 4 wt%, which could not withstand practical use with conventional aging treatment, both Br and coercive force increase at an extremely high rate, which is still impractical for practical use. Shows sufficiently satisfactory characteristics. Furthermore, in each cooling process, the holding time at the cooling start or end temperature can be made shorter than before, and overall the aging treatment time can be made shorter than before. Furthermore, there is no need to perform sintering twice. Specific Examples of the Invention The present invention will now be described in more detail with reference to Examples. Example 1 Weight percentage: 24.5% Sm, 5% Cu, 15% Fe,
An alloy consisting of 1.0% Zr, 0.5% Hf, 0.5% Ti, and residual Co was fabricated by high-frequency induction melting. Next, this was coarsely pulverized with a geo crusher and finely pulverized with a jet mill. This was molded in a magnetic field, sintered and solution treated in vacuum at 1200°C for 1 hour, and cooled to room temperature. The heat treatment was repeated twice by changing T ₁ and t ₁ with a cooling start temperature T ₁ and a cooling end temperature t ₁ in a profile as shown in FIG. 1. Figure 3 shows the relationship between iHc and T ₁ , and Figure 4 shows the relationship between iHc and T 1.
The relationship with t ₁ is shown by a solid line. In addition, in FIGS. 3 and 4, in the profile of the conventional multi-stage aging treatment shown in FIG. 2, the holding times are a=2Hr, b=1Hr, c
The result when =1Hr is shown by the broken line. From these results, it is clear that the present invention is effective in performing predetermined aging heat treatment two or more times. It can also be seen that T ₁ is preferably 750 to 950°C, and t ₁ is preferably 700°C or less. Furthermore, it can be seen that the total aging treatment time is also shortened. Example 2 Similar to Example 1, alloy No. 1 ~ shown in Table 1
I got 8. After crushing, sintering, and solution treatment in the same manner as in Example 1, the following heat treatments A, B, and C were performed to obtain samples 1A to 10C. A: In the profile shown in Figure 1, T ₁ = 850°C, t ₁ = 400°C. B: In the three profiles in Figure 5, T ₁ = 900°C, T ₂ = 850°C, T ₃ = 800°C, t ₁ = 500°C, t ₂ = 450°C, t ₃ = 400°C. C: In the one-time profile shown in Figure 2,
T ₁ = 850℃, t ₁ = 400℃, a = 6Hr, b = 1Hr,
When c=4Hr. Magnetic properties of samples 1A to 10C, Br, iHr,
Table 2 shows (B·H)max and magnetization rate. In this case, the magnetization rate is the value of Br when magnetized by applying 15KOe,
This is the value divided by Br when fully magnetized. Further, Table 2 shows the increase rate of each of these characteristics with respect to treatment C.

【table】

【table】

[Table] From the results in Table 2, the effects of the present invention are clear. In addition, the samples obtained by subjecting alloys No. 1 to 7 of the present invention to treatments A and B are alloy No. 8 in which Zr was added alone.
It shows magnetic properties comparable to those of the samples treated with A and B. Comparative Example The powder of Alloy No. 1 of Example 1 was molded using a magnetic field press, and then heated at 1180 to 1210°C for 30 minutes in an argon stream depending on the Cu content, and then at 1190 to 1210°C for 30 minutes.
It was sintered at 1220°C for 1 hour. Next, isothermal treatment at 650℃ for 1 hour, followed by 800℃
The starting temperature was 3°C to 400°C at a cooling rate of 0.1°C/min. The alloy thus obtained according to JP-A-57-161044 is designated as sample 1D. Furthermore, using this alloy No. 1, after crushing, sintering, and compacting treatment in the same manner as in Example 1, heat treatment A,
In B, the same heat treatment was performed except that the cooling rate was changed to 120° C./min. These respective heat treatments are referred to as heat treatments E and F, respectively, corresponding to heat treatments A and B, and the samples obtained in this manner are referred to as samples 1E and 1F. Squareness ratio and iHc were measured for these samples. Squareness ratio is expressed as Hk/iHc (%), where Hk is 90%
This is the value of H at the intersection of the Br line and the demagnetization curve. The results are shown below along with the samples of the invention.

[Table] From these results, the effects of the present invention are clear.

[Brief explanation of drawings]

FIG. 1 is a temperature-time profile graph showing one example of the heat treatment method of the present invention. FIG. 2 is a graph of a temperature-time profile illustrating an example of a conventional heat treatment method. 3 and 4 are graphs of coercive force −T ₁ and coercive force _{−t 1 when} T ₁ and t 1 of the profiles of FIGS. 1 and 2 are changed, respectively. In this case, in FIGS. 3 and 4, the solid line corresponds to the profile in FIG. 1, and the broken line corresponds to the profile in FIG. 2. FIG. 5 is a temperature-time profile graph showing another example of the heat treatment method of the present invention.

Claims (1)

[Claims] 1. 22 to 28% R (R is one or more rare earth elements), 2 to 10% Cu, 6 to 35% T (T is Fe,
one or more of Ni, Mn and Cr), 0.5 to 6%
M (M is a combination of Zr and/or Hf and one or more of Ti, Nb, V and Ta), the balance being Co
After sintering and solution treatment of a rare earth cobalt-based intermetallic compound having a composition mainly consisting of A method for heat treatment of permanent magnet materials, characterized by repeating heat treatment for cooling at a high speed two or more times. 2. The method of heat treating a permanent magnet material according to claim 1, wherein the Cu content is 2.5 to 8%. 3. The method according to claim 1 or 2, wherein T is Fe or a combination of Fe and one or more of Ni, Mn and Cr, and the Fe content is 10 to 25%. Heat treatment method for permanent magnet materials. 4. The method of heat treating a permanent magnet material according to any one of claims 1 to 3, wherein the sintering and solution treatment temperatures are 1000°C or higher. 5 The quenching end temperature after sintering and solution treatment is
5. The method of heat treating a permanent magnet material according to any one of claims 1 to 4, wherein the temperature range is from the first cooling start temperature of 750 to 950°C to room temperature. 6. The method of heat treating a permanent magnet material according to any one of claims 1 to 5, wherein the cooling end temperature of each cycle is within a temperature range from 650°C to room temperature. 7. The method of heat treating a permanent magnet material according to any one of claims 1 to 6, wherein the heat treatment is repeated 2 to 4 times. 8 Claims 1 to 7 provide a holding time of 5 minutes to 20 hours at each cooling start temperature.
A method for heat treatment of a permanent magnet material according to any one of paragraphs.