Beryllium copper

An alloy mainly made of copper and beryllium. In the past, it was called beryllium bronze, but tin is usually not added, and cobalt is often added. When an alloy containing about 2% beryllium by weight is solutionized at about 800°C, quenched, slightly plastically worked, and heated to the low 300°C range, it hardens significantly, and has a tensile strength of about 130 kilograms per square millimeter, which is unparalleled in traditional copper alloys. There are various variations, broadly divided into high-strength alloys that utilize this fact, and low-beryllium alloys that are hardened only to the extent that can be obtained with a beryllium content of about 0.5% by weight, and silver is added to make them high-strength, high-conductivity alloys. In addition to the usual heat treatment, mill-hardened materials have also been produced in recent years, in which the material manufacturer performs the heat treatment and the user only needs to perform the molding process. There are also cast products, and they are used for undersea cable parts, plastic molding dies, explosion-proof tools, etc.

[Ryōtsugu Mishima]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

銅にベリリウムを加えたものを主体とする合金。昔はベリリウム青銅といったこともあるが、スズは普通加えず、コバルトを加えることが多い。ベリリウムを2重量％近辺入れた合金を800℃付近で溶体化して焼き入れたのち若干の塑性加工を加え、300℃台の前半に加熱すると著しく硬化し、昔からの銅合金に類をみない130キログラム／平方ミリメートル台の引張り強さをもつということを利用する高力合金と、0.5重量％近辺のベリリウムに抑えても得られる程度の硬化にとどめ、銀などを加えて高力高電導合金とする低ベリリウム合金とに大別され、各種の変種がある。また高力型でも本来の熱処理のほかに、素材製造者が行っておき、使用者は成形加工のみですませるミルハードン材も近年つくられている。鋳造品もあり、海底ケーブル部品、プラスチック成形金型、防爆工具などに使われる。

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