JPH0362775B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a rare earth cobalt-based permanent magnet alloy. [Prior art] Rare earth cobalt magnets made of rare earth element R and cobalt are roughly divided into two types: RC ₀₅ series and two-phase separated type R ₂ (CoFeCuM) ₁₇ series containing Cu and Fe. Energy product (BH) _nax is RCo ₅ series
25MGOe, R ₂ (CoFeCuM) ₁₇ series reaches 33MGOe, which is extremely high compared to 10MGOe for alnico magnets and 4MGOe for Ba ferrite magnets, so it is especially used in equipment that requires miniaturization and equipment that requires a strong magnetic field. There is. However, the temperature coefficient of magnetic flux is large, for example, approximately -0.04%/°C for SmCo ₅ system, approximately -0.03%/°C for two-phase separated Sm ₂ Co ₁₇ system, and -0.022 to 0.016%/°C for alnico magnets. Because of their comparative inferiority, it was difficult to use them in environments with rapid temperature changes. Incidentally, recently, various electric measuring instruments and communication devices are required to be more and more compact, lightweight, high performance, and highly reliable. To make devices smaller and lighter, magnets with high (BH) _nax are required.
In particular, in order to make the magnet thinner, there is a need for a magnet that also has _a high coercive force _IHC . For example, rare earth cobalt magnets have been used as periodic magnets in traveling wave tubes for communication satellites to make them smaller and lighter, and in recent years, traveling wave tubes have also become smaller and have larger capacities. increasingly high (BH) _n
AX and _{high IHC} magnets are in demand. Furthermore, in order to improve the performance and reliability of devices, there is a need for magnetic flux that exhibits small changes even when the temperature of the environment in which the device is used changes. For example, the temperature environment that satellites are exposed to in space is extremely harsh, ranging from -50 to +150 degrees Celsius, and in order to improve the performance and reliability of traveling wave tubes, there is a strong need for magnets whose magnetic flux changes little with temperature. . To meet these demands, permanent magnets in which a portion of Sm is replaced with heavy rare earth elements such as Gd, Er, Ho, Tb, and Dy have been proposed as rare-earth cobalt magnets with improved temperature coefficients of magnetic flux. 1977
-75919, 50-81914, 51-52319). but,
These are essentially magnets based on RCo ₅ ,
Although its reversible temperature coefficient is small at 0 to -0.03%/°C, its (BH) _nax is low at 8 to 13 MGOe, making it unable to adequately cope with miniaturization of various devices. Therefore, in order to develop a magnet with high (BH) _nax and a small temperature coefficient of magnetic flux, it is necessary to consider the use of a two-phase separated R ₂ (CoFeCuM) ₁₇ alloy with high magnetization. By the way, two-phase separated R ₂ (CoFeCuM) _17- based magnets are manufactured by aging an alloy containing Cu and Fe to separate the two phases into RCo ₅ phase and R ₂ Co ₁₇ phase, and then magnetically harden the magnet. However, its _I H _C is generally low, and therefore it cannot be used in a shape with a low permeance coefficient _.
It is necessary to increase H _C. [Object and Structure of the Invention] The present invention has been made in view of the above circumstances, and its object is to provide a permanent magnet with a small temperature change in magnetic flux and a high coercive force _I H _C9 maximum energy product (BH) _nax . An object of the present invention is to provide a method for manufacturing a magnetic alloy. In order to achieve such an objective, the present invention
Alloy powder A having a composition represented by Sm(Co _1-abc Fe _a Cu _b M _c ) _z is mixed with alloy powder B having a composition represented by X(Co _1-abc Fe _a Cu _b M _c ) _z , It is compression molded and then sintered. Here, M is at least one of Ti, Zr, and Hf;
X is a heavy rare earth element Gd, Tb, Dy, Ho, Er,
Any one of Tm, and 0.05≦a≦0.35,
0.03≦b≦0.15, 0.005≦c≦0.05, 7.0≦z≦8.3
It is. As a permanent magnetic alloy with such a small magnetic flux temperature coefficient and high _I H _C and (BH) _nax , the applicant previously proposed (Sm _1-x X _x Gd _y ) (Co _1-abc Fe _a Cu _b M _c ) general formula (wherein, X is one of Pr, Ce, and Mitsushi metal; M is at least one of Ti, Zr, and Hf; ≦
a≦0.35, 0.03≦b≦0.15, 0.005≦c≦0.05, 7.0
≦z≦8.3) (Patent application 1987-146468)
and the general formula of ((Sm _1-x X _x ) (Co _1-abc Fe _a Cu _b M _c ) _z (wherein, At least one of Zr and Hf, and
0.05≦x≦0.7, 0.05≦a≦0.35, 0.03≦b≦0.15,
0.005≦c≦0.05, 7.0≦z≦8.3) (Japanese Patent Application No. 146467/1983). The development principle of these permanent magnet alloys was as follows. That is, in general, when R in an R ₂ Co ₁₇ alloy is made of a light rare earth element, the magnetic flux of the alloy decreases as the temperature rises, similar to a normal magnetic alloy. However, in a Gd ₂ Co ₁₇ alloy in which R is a heavy rare earth element, the magnetic flux of the alloy increases as the temperature rises over a wide range including room temperature. The invention according to the above application provides that the relationship between the magnetic flux and temperature of these alloys is
Sm (Co _1-abc Fe _a Cu b M _c ) _z alloy containing Cu, Fe, and M (M is at least one of Ti, Zr, _and Hf), and X (Co _1-abc Fe _a Cu _b M _c ) Focusing on the fact that the same holds true even when _{a z} alloy (X is at least one of the heavy rare earth elements Gd, Tb, Dy, Ho, Er, and Tm) is subjected to two-phase separation treatment and magnetized,
(Sm _1-x X _x ) ( _{Co 1-abc} Fe _a Cu _b M _c ) Sm (Co _1-abc Fe _a Cu _b
This was based on the discovery that a temperature coefficient of magnetic flux intermediate between the M _c ) _z alloy and the X(Co _1-abc Fe _a C _b M _c ) _z alloy was obtained. Regarding the manufacturing method of such a permanent magnet alloy,
The applicant states that in the specification of the above application, Sm and heavy rare earth elements (Gd, Tb, Dy, Ho, Er, Tm
(one or more types of) were adjusted to obtain the desired magnetic flux temperature coefficient (Sm _1-x X _x ) (Co _1-abc Fe _a Cu _b M _c )
All components of the _z alloy are melted to make an ingot, and the powder obtained by crushing this is molded in a magnetic field, the molded product is sintered, homogenized, and rapidly cooled to room temperature. It is stated that the product is manufactured by continuous cooling aging. However, when manufacturing magnets with various temperature coefficients of magnetic flux to suit the design of various devices, this method always requires melting elemental raw materials whose composition has been adjusted in advance to suit each desired temperature coefficient. There are significant problems with productivity. On the other hand, with the recent diversification of equipment designs, magnets with various magnetic flux temperature coefficients are being required more than ever. For this reason, as a result of studying a method for manufacturing the above permanent magnet alloy with a desired magnetic flux temperature coefficient with high productivity, we found that Sm containing only Sm as a rare earth element
(Co _{1 - abc} Fe _{a Cu b M c )}
By manufacturing _alloy powder B separately and mixing at least one of the alloy powders represented by B with alloy powder A, a magnet having a desired magnetic flux temperature coefficient corresponding to the mixing ratio can be created. It was discovered that it is possible to produce That is, according to the present invention, if alloy powder A containing only Sm as a rare earth element and alloy powder B containing heavy rare earth element X as a rare earth element are produced in advance, they can be mixed and homogenized as necessary. By performing treatment and then performing cooling aging to cause two-phase separation, it becomes possible to manufacture magnets with various desired magnetic flux temperature coefficients.
Moreover, by precisely changing the mixing ratio of A and B, it is possible to precisely change the magnetic flux temperature coefficient. According to the present invention, permanent magnet alloys are generally manufactured as follows. First, raw materials for each element are mixed to have the compositions A and B described above and melted to obtain an ingot. These ingots are separately coarsely ground and then finely ground using a ball mill, jet mill, etc. to produce alloy powders shown by A and B.
Among these alloy powders, the alloy powder indicated by A is sufficiently mixed with at least one of the alloy powders indicated by B so as to obtain the desired magnetic flux temperature coefficient, and then this mixed fine powder is ~15KOe
The molded product is press-molded in a magnetic field of about 1150 ~
Sinter at a temperature of 1230℃ for about 15 minutes to 2 hours.
Sintering is performed at a high temperature of 1150 to 1230℃, so
Diffusion of each element progresses sufficiently, which has the effect of increasing the density and making the composition of each element uniform. For this reason, even though the manufacturing method according to the present invention mixes two or more types of powder, the composition of each element after sintering is uniform, and the subsequent processing steps are performed when starting from one type of powder. can be treated in the same way. After this, solution treatment is performed at 1100 to 1190°C for 1 hour or more. By performing this solution treatment for a long time, it is possible to increase _I H _C after aging, which will be described later. In particular, by performing this solution treatment for 5 hours or more, a very high _I H _C of 15 KOe or more can be obtained. After this solution treatment, initial aging is performed at 750 to 950℃ for more than 1 hour, and then at a cooling rate of 1 to 50℃/min.
Two-phase separation treatment with continuous cooling to 450-300°C is performed. Multistage aging may be performed instead of continuous cooling. By carrying out the initial aging for a long time, a fine two-phase separated structure can be obtained, so that _I H _C can be increased, and it is preferable to carry out the aging for 5 hours or more. These melting, crushing, sintering, solution treatment, and aging are
It can be carried out in a variety of atmospheres, including inert,
It is preferable to carry out the reaction in a vacuum or in a non-oxidizing, reducing atmosphere. The limitations on each component and the component ratio of the permanent magnet alloy according to the present invention are due to the following reasons. First, Sm(Co _1-abc Fe _a Cu _b M _c ) _z and X
In the general formula represented by (Co _1-abc Fe _a Cu _b M _c ) _z , Sm is an element necessary to obtain excellent (BH) _nax . As described above, the heavy rare earth element represented by X has the effect of increasing the magnetic flux of the alloy when the temperature rises over a wide temperature range including room temperature. For this reason,
By mixing alloy powder B containing only heavy rare earth element X as a rare earth element with alloy powder A containing only Sm as rare earth element, it has the effect of reducing the magnetic flux temperature coefficient of the alloy. If the ratio z of the total amount of other elements to the total amount of these rare earth elements is less than 7.0, _I H _C decreases and the saturation magnetization decreases, so the residual magnetic flux density Br also decreases. Also, when z exceeds 8.3, _I H _C decreases rapidly, so 7.0≦z≦
8.3 is appropriate. Fe has the effect of increasing saturation magnetization and increasing Br, but the effect is small when a is less than 0.05, and when it exceeds 0.35, _I H _C decreases, so 0.05≦
A≦0.35 is appropriate. Cu is an element necessary for causing a two-phase separation reaction, and has the effect of increasing _I H _C. However, if b is less than 0.03, the two-phase separation reaction will not proceed sufficiently, making it impossible to obtain sufficient _I H _C as a magnet, and if b exceeds 0.15, the saturation magnetization will decrease and Br will decrease. ≦b≦0.15 is appropriate. Adding at least one of Ti, Zr, and Hf as M has the effect of increasing _I H _C.
However, if c is less than 0.005, this effect will not be noticeable, and if c exceeds 0.05, _I H _C will decrease rapidly, so 0.005≦c≦0.05 is appropriate. Hereinafter, the present invention will be explained in detail using Examples. [Example] Example 1 Raw materials prepared to form an alloy of the components shown in Table 1 were arc melted, coarsely ground in an iron mortar, and then
Each alloy powder with an average particle size of 10 to 15 μm was produced by finely pulverizing it in petroleum benzine using a stainless steel ball mill.

[Table] Next, (weight of alloy 2) / (weight of alloy 1 +
The mixing ratio expressed by the weight of Alloy 2 is 0, 0.2,
After blending the powder of Alloy 1 and the powder of Alloy 2 so that the powder is 0.4, 0.6, 0.8, 1.0, thoroughly mixed,
Compression molding was performed using a mold in a magnetic field of 13 KOe at a pressure of 2.5 ton/cm ² . These green compacts are placed in an Ar air stream.
Sintering was carried out at 1210°C for 30 minutes, followed by solution treatment at 1160°C for 6 hours and quenching. Next, initial aging was performed at 850℃ for 10 hours in an Ar flow, and then aged at 350℃.
The sample was continuously cooled at a rate of 1.5°C/min to 350°C for 1 hour. The magnetic properties of the permanent magnet alloy thus obtained are shown in Table 2. The figure also shows the reversible temperature coefficient α of the magnetic flux in the temperature range of -50 to +150°C, which was measured with a permeance coefficient of 2.0.

[Table] First, as can be seen from Table 2, as the mixing ratio of Alloy 2 increases, Br, _I H _C , and (BH) _nax tend to decrease. 13~ if the mixing ratio is 0.6 or less
A high (BH) _nax of 25MGOe has been obtained, which decreases to 9MGOe or less when the mixing ratio is 0.8 or higher.
Therefore, a practical guideline for this mixing ratio is 0.7 or less. On the other hand, as can be seen from the figure, as the mixing ratio of Alloy 2 increases, α decreases, becoming -0.021%/°C at a mixing ratio of 0.2 and almost 0 at a mixing ratio of 0.5. As the mixing ratio further increases, the sign of α turns positive and its value increases. In this way, by mixing alloy powder 1 containing only Sm as a rare earth element and alloy powder 2 containing only Gd, α can be significantly improved and the desired magnetic flux can be achieved by adjusting the mixing ratio. Magnets with temperature coefficients can be manufactured. Example 2 Using raw materials prepared to form an alloy with the components shown in Table 3, the average particle size was 10 to 10, as in Example 1.
Each alloy powder of 15 μm was produced.

【table】

[Table] Next, each alloy powder was mixed to have the mixing ratio shown in Table 4, and then thoroughly mixed to obtain 13KOe.
Compression molding was performed using a mold in a magnetic field of 2.5 tons/cm ² at a pressure of 2.5 tons/cm 2 . These green compacts were heated at 1210℃ in an Ar flow.
The material was sintered for 30 minutes at 1160°C, and then solution treated at 1160°C for 6 hours and rapidly cooled. Then heated to 850℃ in Ar flow.
The first stage aging was performed for 10 hours at
It was continuously cooled at a rate of °C/min and held at 350 °C for 1 hour.

[Table] The magnetic properties and permeance coefficient of the permanent magnet alloy thus obtained were measured with a setting of 2.0 -50
Table 5 shows the reversible temperature coefficient α of the magnetic flux in the temperature range of ~+150°C.

【table】

〔Effect of the invention〕

As explained above, according to the present invention, a two-phase separated Sm ₂ (CoFeCuM) ₁₇ alloy powder and a two-phase separated type
X ₂ (CoFeCuM) ₁₇ series alloy (X is heavy rare earth element Gd,
By mixing Tb, Dy, Ho, Er, Tm) powder, we can improve the magnetic flux temperature coefficient and create a permanent magnet that has the desired magnetic flux temperature coefficient and also has high _I H _C and (BH) _nax . It can be manufactured with high productivity, and can fully meet the demands for magnets with high _I H _C , high (BH) _nax , and various magnetic flux temperature coefficients accompanying the diversification of communication equipment.

[Brief explanation of drawings]

The figure shows the relationship between the reversible temperature coefficient of magnetic flux and the mixing ratio of alloy powder.

Claims (1)

[Claims] 1 Sm(Co _1-abc Fe _a Cu _b M _c ) _z and at least one kind of alloy powder having the composition X(Co _1-abc Fe _a Cu _b M _c ) _z (In each formula, M is at least one of Ti, Zr, Hf,
is one of the heavy rare earth elements Gd, Tb, Dy, Ho, Er, Tm, and 0.05≦a≦0.35, 0.03≦b≦
0.15, 0.005≦c≦0.05, 7.0≦z≦8.3), compression molded in a magnetic field, sintered the molded product, and then subjected to solution treatment by heating at 1100 to 1190°C for 5 hours or more. After the solution treatment, 750 to 950
Initial aging at 1 hour or more at ℃, then further aging at 1 to 50℃/
A method for producing a two-phase separated permanent magnet alloy, characterized by continuous cooling or multistage aging at a cooling rate of 450 to 300°C.