# US RE31,317 E · Rare earth-cobalt system permanent magnetic alloys and method of preparing same

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- Number: US RE31,317 E
- Document ID: USRE31317E
- Status: Granted
- Kind: E
- Application number: 06/209,664
- Filed: 1980-11-24
- Granted: 1983-07-19
- Earliest claimed: 1978-02-03
- Assignees: Namiki Precision Jewel Co., Ltd.
- Inventors: Nobuo Imaizumi; Kazuo Wakana
- Web page: https://patentgrep.com/patent/USRE31317E

## Abstract

Permanent magnetic alloys comprising 11.5-12.5% rare earth components of which 6.3-12% is samarium and 0.5-6.2% is yttrium; 0.2-2.5% hafnium, [19.5-26.5%] 10.5-26.5% iron, 7-10.5% copper, and 52-70.7% cobalt, the ranges of the components being in atomic ratios. The alloys are prepared by obtaining 1-50 .mu.m. powders of the components, compacting the powder after mangetic field orientation sintering the compacted powders at 1160.degree.-1220.degree. for 1-10 hours, cooling the sintered body at a rate of at least 1.degree. C./second until the temperature is about 900.degree. C., and then annealing the body at 750.degree.-900.degree. C.

## Claims

### Claim 1

Permanent magnetic alloys comprising 11.5-12.5% rare earth components of which 6.3-12% is samarium and 0.5-6.2% in yttrium; 0.2-2.5% hafnium, [19.5-26.5%] 10.5-26.5% iron, 7-10.5% copper, and 52-[70.7%] 70.8% cobalt, the ranges of the aforesaid components being in atomic ratios.

### Claim 2 (depends on 1)

A method of preparing the alloys of claim 1 comprising the steps of melting raw material containing said components, solidifying the resulting melt, pulverizing the resulting ingot into powders having a grain size of 1-50 .mu.m, compacting the powders after magnetic field orientation thereof, sintering said compacted powders at 1160.degree.-1220.degree. C. for 1-10 hours, cooling the sintered body at a rate of at least 1.degree. C./second at least until the temperature is about 900.degree. C., and then annealing the resulting bulk at 750.degree.-900.degree. C.

### Claim 3 (depends on 2)

The method as in claim 2 where said annealing occurs at about 850.degree. C. for about 1/2 hour.

### Claim 4 (depends on 2)

The method as in claim 2 where said melting is effected in an inert atmosphere with a high frequency induction furnace or an electric arc furnace.

### Claim 5 (depends on 2, 4)

The method as in claims 2 or 4 where said cooling is effected by quenching the sintered body.

### Claim 6 (depends on 2)

The method as in claim 2 where said grain size of the powders is 1-5 .mu.m.

### Claim 7 (depends on 2)

The method as in claim 2 where the sintered body is cooled to room temperature.