Tokushichi Mishima

Metallurgist. Inventor of MK steel. Born in Awajishima, Hyogo Prefecture. Graduated from the Department of Metallurgy, Faculty of Engineering, Tokyo Imperial University in 1920 (Taisho 9). Became an assistant at the same university, and became an associate professor in 1921, and a professor in 1938 (Showa 13), retiring in 1953. During this time, he received his doctorate in engineering in 1928 for his research on "Annealing Embrittlement of Nickel and Nickel Alloys". In 1931, he invented the famous MK steel. By adding an appropriate amount of aluminum to nickel steel, the physical properties were changed to create a powerful permanent magnet, and it was the first of the aluminum-nickel-cobalt permanent magnets widely used today. The K in MK steel is the initial of his birth family's surname Kizumi, and the M is the initial of his adoptive family's surname Mishima. For this achievement, he received the Imperial Academy Prize in 1945, and became a member of the Japan Academy in 1949. He was awarded the Order of Culture in 1950, and in the following year, in 1951, was designated a Person of Cultural Merit, and was also honored by the American and Italian Metallurgical Institutions. He achieved accomplishments in a wide range of fields, primarily in the field of magnetic alloy research, and served as president of the Japan Society for the Promotion of Science.

[Shin Watanabe]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

金属工学者。MK鋼の発明者。兵庫県淡路島生まれ。1920年（大正9）東京帝国大学工学部冶金(やきん)学科を卒業。同大学助手となり、1921年助教授、1938年（昭和13）教授となり、1953年に退職。この間、1928年「ニッケル及びニッケル合金の焼鈍脆性(ぜいせい)」の研究で工学博士。1931年、有名なMK鋼を発明した。これはニッケル鋼に適量のアルミニウムを添加することによって物理的性質が変化し、強力な永久磁石となったもので、今日、多用されているアルミニウム・ニッケル・コバルト系永久磁石の最初のものである。なおMK鋼のKは彼の生家の姓喜住(きずみ)の、Mは養家の姓三島の頭文字である。この業績により1945年帝国学士院恩賜賞を受け、1949年日本学士院会員。1950年文化勲章を受章、翌1951年には文化功労者となり、アメリカ、イタリアの金属学会からも顕彰された。磁性合金の研究を中心に広い分野で業績をあげ、日本学術振興会会長などを歴任した。

［渡辺　伸］

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