JPH0364902A - Permanent magnet and manufacture thereof - Google Patents

Abstract

PURPOSE:To enhance the mechanical strength of the title permanent magnet without impairing its magnetic characteristics by a method wherein, when the powder of the permanent magnet, which is an intermetallic compound of a rare-earth element and transition metal element, is sintered, the sintering is conducted by adding a sintering strength reinforcing metal powder. CONSTITUTION:A rare-earth element and a transition metal element are mixed with specific ratio and melt in a heating furnace, to produce an alloy and powder for sintered magnet material is produced by crushing said alloy ingot. It is desirable to form sintering strength increasing metal in such a manner that at least a kind of metal is selected from Fe, Co and Ni and mixed with specific ratio, then the mixture is melted in the heating furnace to produce an alloy, and the ingot of the alloy is crushes to produce the powder for sintering strength increasing material. Then, the sintering magnet powder material and the sintering strength increasing powder material are mixed, and after the mixture has been molded under a magnetic field, it is heated up and sintered in an inert gas atmosphere. Then, the above- mentioned material is heat-treated by heating it in the same inert gas atmosphere at the temperature lower than the sintering temperature in order to increase its coercive force, thereafter it is processed into the prescribed shape, and the molded body is magnetized. When the grain diameter of the sintered magnet material is sufficiently larger than the grain diameter of the sintering strength increasing powder material, magnetic characteristics are not impaired, and when the grain diameter is almost equal, mechanical strength is excellent.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a permanent magnet containing an alloy of a rare earth element and a transition metal element and having excellent mechanical strength, and a method for manufacturing the same.

(Prior Art) In recent years, permanent magnets made of alloys of rare earth elements and transition metal elements have been widely used. The permanent magnet is an intermetallic compound (R-M) of a rare earth element (R) and a transition metal element (M).
), rare earth elements (R) include cerium Ce, praseodymium Pr, neodymium Nd, samarium Sm, etc., and transition metal elements (M) include manganese Mn,
Iron (Fe), cobalt (Co), nickel (Ni), etc. are used.

The permanent magnet, which is an intermetallic compound (RM), has a maximum magnetic energy product (B - H) max compared to conventional permanent magnets such as ferrite magnets, alnico magnets, and iron/chromium/cobalt magnets. Because it is large, it is small and powerful. Therefore, by using a permanent magnet that is the intermetallic compound (RM), it is possible to downsize a device that uses a permanent magnet.

(Problem to be solved by the invention) A permanent magnet that is such an intermetallic compound (RM) is
Since it has low mechanical strength and poor toughness, it has the disadvantage that it will instantly break if the external stress applied to the permanent magnet exceeds a limit value. Therefore, there is a problem that its use is restricted to places that are constantly subjected to stress during operation, such as the rotor of a rotating electric machine.

(Means for Solving the Problems) The present invention has been made in view of the above points, and when sintering permanent magnet powder that is an intermetallic compound (RM),
Iron Fe, cobalt magnet, nickel N as sintering strength materials
The purpose of the present invention is to provide a permanent magnet whose mechanical strength can be increased without impairing its magnetic properties by adding and sintering powder made of one of these types or an alloy thereof, and a method for manufacturing the same. .

(Function) In the permanent magnet and its manufacturing method of the present invention, permanent magnet powder with a large maximum magnetic energy product is fired together with magnetic metal powder, so it has excellent magnetic properties and high mechanical strength. It is also possible to provide an excellent permanent magnet and its manufacturing method.

(Example) A method for manufacturing a permanent magnet according to the present invention will be described with reference to the drawings.

FIG. 1 is a flow diagram showing a method for manufacturing a permanent magnet according to the present invention.

Steps 1 to 4 are performed using conventional intermetallic compounds (FL-
M) Same as the manufacturing method of permanent magnets, a predetermined amount of rare earth element (R) and transition metal element (M) are mixed and melted in a heating furnace to form an alloy, and an ingot of the alloy is crushed to form a sintered magnet. Manufacture material powder.

In steps 5 to 8, a predetermined amount of at least Class 1A of iron Fe, cobalt Co, and nickel NL, which are sintering strength materials, are mixed and melted in a heating furnace to create an alloy, and an ingot of the alloy is made. Grind to produce powder of sintered strength material.

In the next step 9, the powder of the sintered magnet material produced in step 4 and the powder of the sintered strength material produced in step 8 are mixed.

In the next step 10, the mixed powder obtained in step 9 is molded in a magnetic field.

In the next step 11, the molded product in step 10 is heated and fired in an inert gas atmosphere such as argon.

In the next step 12, the material fired in step 11 is heated in an inert gas atmosphere to a temperature lower than the firing temperature to increase the coercive force.

In the next step 13, it is processed into a predetermined shape, and if necessary, the surface is subjected to anti-rust treatment.

In the next step 14, the molded product in step 13 is magnetized.

Then, in the final step 15, inspection such as flaw detection is performed to complete the permanent magnet.

The structure of the permanent magnet manufactured by the above manufacturing method will be explained.

FIG. 2 is a diagram showing the structure of the permanent magnet of the present invention.

This figure (a) is a diagram showing a case where the particle size of the powder of the sintered magnet material manufactured in step 4 is sufficiently larger than the particle size of the powder of the sintered strength material manufactured in step 8. .

Moreover, this figure (b) is a diagram showing a case where the particle size of the powder of the sintered magnet material manufactured in step 4 and the particle size of the powder of the sintered strength material manufactured in step 8 are almost equal. be.

In the case shown in (a), the spacing between the powders of the sintered magnet material is small, so the magnetic properties are not impaired, and in the case shown in (b),
Sintered strength: The powder of the material is well bonded to each other, so it has excellent mechanical strength.

Therefore, the relationship between the particle size of the powder of the sintered magnet material and the particle size of the powder of the sintered strength material can be arbitrarily set depending on the purpose of the permanent magnet, that is, whether emphasis is placed on strength or magnetic properties. can.

The embodiments of the permanent magnet and the manufacturing method thereof of the present invention have been described in detail above, but various different embodiments can be easily constructed without departing from the spirit of the present invention. Other than the limitations set forth in the scope, there are no limitations to the particular embodiments.

(Effects of the Invention) As explained above, according to the present invention, since permanent magnet powder with a large maximum magnetic energy product is fired together with magnetic metal powder, it has excellent magnetic properties and is mechanically It is possible to provide a permanent magnet with excellent physical strength and a method for manufacturing the same.

[Brief explanation of drawings]

FIG. 1 is a flow diagram showing the manufacturing method of the present invention, and FIG. 2 is a diagram showing the structure of the permanent magnet of the present invention.

Claims (8)

[Claims] (1) A step of mixing a magnetic powder made of an alloy of a rare earth element and a transition metal element with a powder of a metal element for increasing sintering strength, and a step of molding the mixture in a magnetic field;
A method for manufacturing a permanent magnet, comprising the steps of heating and firing the molded product and magnetizing the fired product. (2) The method for producing a permanent magnet according to claim (1), wherein the powder of the metal element for increasing sintering strength is made of an alloy of one or more of iron, cobalt, and nickel. . (3) The method for manufacturing a permanent magnet according to claim (2), wherein the particle size of the magnetic powder and the particle size of the metal element powder for increasing sintering strength are approximately the same. (4) The method for manufacturing a permanent magnet according to claim (2), wherein the particle size of the magnetic powder is larger than the particle size of the powder of the metal element for increasing sintering strength. (5) A permanent magnet comprising a sintered body of a magnetic powder made of an alloy of a rare earth element and a transition metal element and a powder of a metal element for increasing sintering strength. (6) The permanent magnet according to claim (5), wherein the powder of the metal element for increasing sintering strength is made of one or an alloy of two or more of iron, cobalt, and nickel. (7) The permanent magnet according to claim (6), wherein the particle size of the magnetic powder and the particle size of the metal element powder for increasing sintering strength are approximately the same. (8) The permanent magnet according to claim (6), wherein the particle size of the magnetic powder is larger than the particle size of the powder of the metal element for increasing sintering strength.