JPS5827304A - Rare-earth material for permanent magnet - Google Patents

Abstract

PURPOSE:To increase coercive force and to obtain a high energy product without lowering the density of a residual magnetic flux by a method wherein magnetic material of two-phase separate type R2T17 series is allowed to contain 0.005- 0.35wt% of carbon. CONSTITUTION:Traces of carbon cause coercive force IHC to sharply increase, to reach its maximum when C=0.05wt% and to gradually decrease when 0.05wt% or more of carbon is contained. On the other hand, Br tends to slightly decrease as the amount of C added is increased. Consequently, the amount of C contained within the range of 0.005wt% to 0.35wt% is discovered suitable according to the observation of the (BH)max curve. Thus, because of the carbon contained in the magnet of two-phase separate type R2Co17 series, carbonic compounds are educed in metal magnetic phases and crystalline grain boundaries and this helps coercive force to increase and the two-phase separation to be properly brought about without reducing the density of a residual magnetic flux, causing a magnet to be provided with a high energy product.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is typified by a samarium cobalt magnet. Regarding rare earth permanent magnet materials, which are intermetallic compounds of yttrium and rare earth metals (6) and transition metals (T'),
This invention relates to the improvement of phase-separated R2T1γ permanent magnet materials.

A rare earth cobalt magnet using copal (Co) as the transition metal will be described below.

Rare earth cobalt alloys are ROos, R20o7
, R20oz7, etc. is known to take several compound forms. By the way, in terms of magnetic properties, ROo
5 is the best, and TLOoB permanent magnet materials are in practical use.

By the way, since RzOoty has a small coercive force (IHO), it cannot be used as a permanent magnet material. However, the saturation magnetic flux density (Bs) and the Kiley temperature (T
Regarding c), RC! higher than o5 (e.g. Sm
At 20o17, Bs = 12K Gauss, Tc =
For Sm0o5, Bs=10.
7K Gauss, Tc = 724°C).

Moreover, the crystal anisotropy constant also shows a fairly high value of 5×10 7 erg/.3. Therefore, R2001? is R.O.
It is expected to be used as a permanent magnet material following o5.

As mentioned above, R20o17 has a small coercive force.

In order to use it as a permanent magnet, it is urgently necessary to improve the coercive force.

So far, R20o17-based permanent magnet materials.

The R20o17 phase was finely precipitated in the ROo5 matrix. Although it is a two-phase separation type material, some of the co is
It has been found that the coercive force can be improved by substituting with . Therefore, currently with R20o17 magnets,
Partial replacement of Co by O has become the mainstream for improving its properties.

The coercive force is improved by substitution with Cu because O is R
This is thought to be due to promoting the refinement of the 20017 phase.

An object of the present invention is to provide an inexpensive two-phase separation type R20o17 magnet with improved coercive force.

The present invention is a two-phase separation type R20o17 magnet containing carbon, and due to the presence of this carbon.

Carbon compounds precipitate within the metal magnetic phase and at grain boundaries, improving coercive force IHC and properly performing two-phase separation. As a result, the coercive force IHC is improved without substantially reducing the residual magnetic flux density Br.

A magnet with a high energy product is obtained.

The magnet material of the present invention is manufactured by a method for manufacturing a nine-piece magnet. That is, melting of raw materials, pulverization (coarse and fine pulverization), magnetic field orientation, compression molding, and sintering.

Manufactured through various steps of solution heat treatment (aging). Melting is a levitation arc9. It is carried out in an inert atmosphere by means such as radio frequency. In some cases, it is performed in a vacuum. Coarse grinding is done in an iron mortar, brown mill, etc.
Fine pulverization is performed using a ball mill, vibration mill, jet mill, etc. Orientation in a magnetic field and compression molding are usually performed at the same time when using a mold, and the orientation magnetic field is
25 to 6e, and the molding pressure is 0.4 to 10 ton/Fu. Sintering is carried out in an inert atmosphere such as Ar or He or in vacuum at a temperature range of 1150 to 1250''C. Solution treatment generally proceeds simultaneously with sintering.

If necessary, the two steps may be separated.

Heat treatment is performed at 700-900°C.

Example Sm is 25.8 wt%, O is 9 wt%, Fe is 1
5wt%.

The alloy was melted by high frequency heating in an argon atmosphere so that Zr was 1.6 wt%, Ti was 0.15 wt%, C was 0.002 to 0.5 wt%, and the balance was Co. Next, this alloy was coarsely ground, and then finely ground to an average particle size of about 4 μm using a ball mill. These alloys were molded in a magnetic field of 10 to 6 e or more with a power of +1 tonl,.2. The molded product was sintered at 1210° C. for 1 hour in an Ar atmosphere, and then solution-treated at 1180° C. for 1 hour. This sintered body was heat treated at 800° C. for 1 hour, and then cooled to 300″G at a cooling rate of 5° C./min or less.

The magnetic properties of this sample are shown in the figure.

As is clear from the figure, if even a small amount of carbon enters, IHC
increases rapidly and reaches a maximum at +c-0.05 wt%, and gradually decreases at C content of 0.05 wt% or more. On the other hand, Br decreases little by little as C is added. Therefore, it can be seen from the curve of (BH)may that the content of C is suitably in the range of 0.005 wt% to 0.35 wt%.

As described above, according to the present invention, by adding carbon,
Significant improvements in IHC and (BH)max are achieved.

[Brief explanation of drawings]

The figure is a graph showing the relationship between carbon content and magnetic properties. (F (N (Ni) 1 (C content (wtγ.)

Claims (1)

[Claims] 1. A two-phase separation type R2T17-based magnet material (wherein R represents yttrium, a rare earth element, and T represents a transition metal), and is characterized by containing o, oos to 0.35 wt% of carbon. Rare earth permanent magnet material.