Permalloy (English spelling)

Japanese: パーマロイ（英語表記）permalloy

A type of alloy steel for special purposes. In 1916, GW Elmen discovered that an alloy of nickel (Ni78.5%) and iron (Fe21.5%) exhibited an unusually high initial magnetic permeability (about 9000) and low coercivity (less than 0.05 Oersted) when it was rapidly cooled, and named it Permalloy. However, the cooling required delicate control, and if it was not done properly, the precipitation of the superlattice Ni ₃ Fe would cause deterioration of the magnetic property, so it was called Permalloy A and was never put to practical use. The practical products are Permalloy C or Mumetal, which contains copper and chromium, and Molybdenum Permalloy, which contains molybdenum (Mo), all of which have a more stable heat treatability than Permalloy A, with an initial magnetic permeability of 20,000 and a maximum magnetic permeability of 90,000. Supermalloy, an alloy of Ni79%, Mo5%, Fe15.5%, and manganese0.5%, has an even higher initial magnetic permeability of 120,000. These are used in communication devices in weak magnetic fields and as magnetic shielding materials. An iron alloy containing 30-40% Ni is called Permalloy D, and one containing 50% Ni is called Permalloy B, the latter having a higher saturation magnetic field (16,000 gauss) than other varieties. The former is used in small transformers, choke coils, and magnetic shunt alloys, while Permalloy B, which has been anisotropically treated by rolling after heavy processing (called Permalloy E), exhibits square hysteresis and is therefore used in medium magnetic field amplifiers and coil cores for magnetic memory devices (→Magnetic materials). The name Permalloy is a combination of the words permeability and alloy.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

特殊用途の合金鋼の一種。 1916年 G. W.エルメンがニッケル Ni78.5%，鉄 Fe21.5%の合金を急冷すると異常に高い初透磁率 (約 9000) と小さい保磁力 (0.05エルステッド以下) を示すことを発見し，パーマロイと名づけた。しかしこれは冷却の加減が微妙で，誤ると規則格子 Ni₃Fe の析出で磁性が劣化するのでパーマロイAといわれたまま実用にならなかった。実用品は銅，クロムを添加したパーマロイCまたはミューメタル，モリブデン Moを加えたモリブデンパーマロイで，いずれも熱処理性がパーマロイAより安定で初透磁率2万，最大透磁率9万に達する。 Ni79%，Mo5%，Fe15.5%，マンガン 0.5%の合金スーパーマロイは初透磁率 12万とさらに高い。これらは弱磁場の通信機器，磁場の遮蔽材などに使われる。別に Ni30～40%の鉄合金はパーマロイD，Ni50%のものはパーマロイBといい，後者は飽和磁気 (1万 6000ガウス) が他の品種より大きい。前者は小型変圧器，チョークコイル，整磁合金に使われ，またパーマロイBは強加工後の圧延で異方性処理をしたもの (パーマロイEという) が角型ヒステリシスを示すところから，中等の磁場の増幅器，磁気記憶装置のコイル磁心に用いられる (→磁性材料 ) 。パーマロイの名は，透磁率 permeabilityと合金 alloyの合字である。

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