Heat-resistant alloy

A series of alloys designed to have sufficient strength, oxidation resistance, and corrosion resistance at high temperatures for use at high temperatures. For example, gas turbines are often operated at temperatures of over 700 °C, and jet engines at over 1000 °C, and are often operated under high stress or in a severe corrosive environment. For these reasons, heat-resistant steels with increased amounts of Cr, Ni, Co, etc. have been developed and are used as their constituent materials. Furthermore, heat-resistant alloys with Ni or Co as the main components and Mo, W, Nb, Ti, Al, Ta, C, B, Zr, Hf, Re, etc. added alone or in combination with other elements have been developed. Representative examples include Fe-based or Fe-Ni-based alloys such as Timken 16-25-6, A-286, N-155, Incoloy-based alloys, Ni-based alloys such as CMSX-based, Inconel-based, Nimonic-based, Hastelloy-based, René-based alloys, and Co-based alloys such as S-816, X-40, L-605. Of these, alloys with particularly high high-temperature strength are difficult to form by forging, so they are manufactured in the form of precision casting alloys or sintered alloys using powder metallurgy. Heat-resistant alloys whose main components are high-melting point metals such as Mo, W, Nb, and Ta are also being developed, but these are often called refractory alloys.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

高温度で使用することを目的として，高温で十分な強度と耐酸化性，耐食性とを備えるようにつくられた一連の合金．たとえば，ガスタービンは約700 ℃ 以上，ジェットエンジンでは1000 ℃ 以上というような高温度で，しかも大きな応力あるいははげしい腐食性環境のもとで運転されることが多いため，それらの構成材料として耐熱鋼のCrやNi，Coなどの添加量を増し，さらにはNiやCo自体を主成分としてMo，W，Nb，Ti，Al，Ta，C，B，Zr，Hf，Reなど種々の元素を単独にあるいは多数組み合わせて添加した耐熱合金が種々開発され使用されている．代表的なものとしては，Fe基ないしFe-Ni基のTimken 16-25-6，A-286，N-155，Incoloy系などの各種合金，Ni基ではCMSX系，Inconel系，Nimonic系，Hastelloy系，René系などの各種合金，Co基ではS-816，X-40，L-605などがあげられる．これらのうち，とくに高温強度の大きい合金は鍛造による成形加工が困難なため，精密鋳造合金や粉末冶金による焼結合金の形で製造される．なお，Mo，W，Nb，Taなどの高融点金属を主成分とする耐熱合金も発展しつつあるが，これらは耐火合金(refractory alloy)とよばれることが多い．

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