US2027996A - Strong permanent magnet with cobalt - Google Patents

Description

Patented Jan. 14, 1936 UNITED STATES STRONG PERMANENT MAGNET WITH COBALT Tokushichi Mishima, Ochiai-machi, Toyotama-gori, Tokyo, Japan No Drawing. Original application January 20,

1932, Serial No. 587,822.

Divided and this application May 31, 1933, Serial No. 673,796. In

Japan August 27, 1931 4 Claims. (01. 175-21) The invention relates to a strong permanent magnet and forms a divisional application to Serial No. 587,822 filed January 20, 1932.

In my co-pending application No. 587,822, I

5 fully explained a new permanent magnet comprising 5 to 40% Ni, 7 to 20% Al and the remainder substantially iron, with or without the addition of other metals, and carbon below 1.5% and also small impurities. The subject matter of the 10 invention is a division from the above mentioned application.

It is described in the above mentioned application No. 587,822, that an irreversible nickel steel can be changed into a "reversible steel by adding aluminum, yielding a strong magnetic al- 10y. According to the invention it has been found that an addition of cobalt in a proper amount can also improve the magnetic properties of the alloy. In addition, its tenacity and ductility are much improved and the mechanical working is made very easy.

It is knownthat the more minute the microstructure of magnet, steels is the more increases the number 01' the molecular magnets arranged irregularly at the boundaries of the crystal grains, so that consequently the coercive force and the residual magnetism also increase. The invention is also based on this principle, and it is found that the addition of 0.5%-40% cobalt to the new alloy containing nickel, aluminuim and iron in the proportion as mentioned above. will make the crystal grains minute, and in consequence increase the coercive iorce and residual magnetism.

The actual examples for carrying out the invention thus modified are given below:

' Ohemicol composition (percent). Magnetic properties Coercive Residual 40 Iron Nickel g Cobalt loroe (He) magnetism (saw) r (s w) 00 0 17. 0 9. 0 5. 0 9, 400 65 0 16. 0 9. 0 10. 0 185 10, (III 50 4 12. 4 7. 0 80. 0 9, mo 5 oo o 24.8 10.0 5.0 200 9,800 I 52 8 30. 5 12 0 4. 5 510 0, M

That is to say, the cobalt added in proper proportions named, besides giving to the alloy the above mentioned characteristics, also serves to make crystal grains minute, thereby improving the magnetic properties of the alloy. It is also 5 given a high coercive force and a strong rmidual magnetism without being quenched after casting, and the mechanical working of the alloy is made easy. In this case also it is noted that the presence of carbon of below 1.5% and/or a small 10 amount of impurities does not materially affect the magnetic properties of the alloy.

What I claim is:--

1. A permanent magnet comprising 5 to 40% nickel, 7 to 20% aluminum, 0.5 to 30% cobalt and 15 the remainder iron.

2; A permanent magnet comprising 5 to 40% nickel, '7 to 20% aluminum, 0.5 to 30% cobalt and the remainder substantially iron.

3. A permanent magnet comprising 5 to 40% 20 nickel, 7 to 20% aluminum, 0.5 to 30% cobalt, from trace to 1.5% carbon and the remainder iron.-

4. A permanent magnet comprising 5 to 40% nickel, 'I to 20% aluminum, 0.5 to 30% cobalt, 25 from trace to 1.5% carbon and the remainder substantially iron.

' TOKUSHICHI MISHIMA.