J. Japan Inst. Metals, Vol. 67, No. 4 (2003),
pp. 205-208

Creep Strengths of a Ni-Base Single Crystal Superalloy TMS-82+ and Its Tie-Line Alloys

Yutaka Koizumi¹, Toshiharu Kobayashi¹, Tadaharu Yokokawa¹, Makoto Osawa¹, Hiroshi Harada¹, Takehisa Hino² and Yomei Yoshioka²

Abstract:

The γ^′ fraction dependence of the creep properties of the second generation single crystal (SC) Ni-base superalloy, TMS-82+, and their γ/γ^′ tie-line alloys is presented. The γ^′ fraction is varied between 0 and 100%. The γ and γ^′ phases of the alloys are designed to have the same chemical composition so that γ^′ fraction dependence can be assessed independently. The γ single-phase alloy is weaker than the γ^′ single-phase alloy. The best creepproperty is obtained with the γ^′ fraction between 60 and 70%, depending on the creepcondition. The optimum γ^′ fraction decreases at higher temperature and lower stress. The SC alloys show larger γ^′ fraction dependence compared with the conventionally cast polycrystalline alloys previously reported.

(Received December 4, 2002)

Keywords:

nickel-base superalloys, single crystal, γ phase, γ^′ phase, creep, TMS-82+

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