The Foundation: the Research Institute of Electric and Magnetic Alloys

Hiroshi Matushima, Executor

Kiyoshi Watanabe

Hakaru Masumoto, Deceased

The disclosed permanent magnet has a coercive force of larger than 500 Oe, a residual magnetic flux density of larger than 5 kG, and a maximum energy product of larger than 2 MGOe, and it consisting essentially of 48.about.66.9 Atm % of iron, 33.about.47 Atm % of platinum, and 0.1.about.10 Atm % of niobium. It includes a crystal structure of an incomplete single .gamma..sub.1 phase of a face-centered tetragonal system due to either the composition thereof or heat treatment applied thereto. The permanent magnet is made by heating an alloy of the above main composition at 900.degree..about.400.degree. for one minute to ten hours and quenching the alloy at a high speed of faster than 30.degree. C./minute but slower than 2,000.degree. C./sec.

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Tokyo, Japan

Hiroshi Matushima, Executor