US2105658A - Permanent magnet - Google Patents

Description

MAGNET Kotaro Honda, Sendai, Japan No Drawing. Application November 19, 1935, Serial No. 50,618. In Japan May 1, 1933 3 Claims.

This applicationforms a continuation in part of my copending application Ser. No. 735,898 filed July-18, 1934 and also of the parent application Ser. No. 697,874, filed November 13, 1933, both pending.

This invention relates to improvements in permanent magnets and more particularly to a permanent magnet made of an alloy consisting of nickel, titanium, cobalt and iron, and has for its object to provide a permanent magnet which has steels are greatly aiiected by temperature variations and mechanical shocks and show unstable magnetic properties.

This invention is to obviate the above mentioned defects and to provide a permanent magnet pf comparatively small dimension-ratio having stable magnetic properties for temperature changes and mechanical shocks and particularly high coercive force.

The alloy used in this invention can be obtained by melting together nickel, titanium, co-

balt and iron-in the proportion of 20 to of nickel, 3 to 10% of titanium, 0.5 to of cobalt and the remainder iron and a small amount of impurities. The molten product may be cast in 35 a suitable mold or sucked up into a tube. or refractory material to give a desired shape. The cast products are preferably annealed at a. suitable temperature such as 500? to 800 C. to give it stability. 40 The above alloy may be more conveniently obtained in practice. by melting together iron or mild steel, nickel, cobalt and. ferro-titanium.

As for example, the following alloy shows magnetic properties as follows:-

Such magnetic properties are obtained by casting the alloy and afterwards annealing it at about 670 C. for two hours. It will be recognized that the above alloy shows particularly high coercive force. v

The above alloys may also contain aluminium, copper, manganese, molybdenum, arsenic and vanadium in the proportion of less than 6% each for further increasing of the residual magnetic induction and-the coercive force. a 10 The inventor has found out that the above alloy is specially well adapted for the manufacture of permanent magnets and more especially of smaller dimension-ratio and it has very stable structureat a temperature below about 700 C. 15 and its magnetic properties are not substantially affected by the change of temperatures and thus the inventor has made use of the above alloy for the manufacture of permanent magnets for fine instruments and also for heat resisting 20 purposes.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A permanent magnet made of an alloy con-' 25 taining 20 to 40% of nickel, 3 to 10% of titanium, 0.5 to 60% of cobalt vanadium in an amount less, than 6% and at least 20% iron and a small amount of impurities, characterized by a-coercive force in the neighborhood of 250 gausses or 30 more.

2. A permanent magnet having a small ratio of length to diameter formed of an alloy containing as essential ingredients 20 to 40% of nickel, 3 to 10% of titanium, .5 to 60% of cobalt vanadium 35 in an amount less than 6% and at least 20% iron and a small amount of impurities, characterized by a coercive force in the neighborhood of gausses or more, long durability and magnetic w stability with respect to mechanical shocks and temperature below about 700 C.

, 3. A permanent magnet formed of an alloy containing as essential ingredients about 21% nickel, about 7% titanium, about 9% cobalt va- 5 KOTARO HONDA. 60