A-24 γ'相の結晶方位ミスオリエンテーションに着目したNi基超耐熱合金のクリープ劣化診断法(材料,一般講演)

概要

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The cost of the turbine blades for the gas turbine engines is increasing, because the latest superalloys for the turbine blades contain precious elements (i.e. precious metals, rare-earth metals) and the casting processes come to be complicated (i.e. directionally solidification, single crystal) to give higher creep resistivity against the increasing turbine inlet gas-temperature (TIT). Therefore, provision of a proper exchange period for the turbine blade can effectively reduce the life cycle cost in the gas-turbine engine operation. In this study, X-ray super-lattice reflections from the γ' precipitate with L1_2 type crystalline structure were carefully evaluated, and the full width at half maximum (FWHM) of ω rocking curves of them were increased as the creep life fraction. This increase in FWHM of the ω rocking curves was thought to reflect the degree of the misorientation among the γ' precipitates. It was also supported by the electron backscatter patterns (EBSP) analysis. Although the reason of the relationship between creep life fraction and the γ' misorientation must be revealed in further study, this evaluation method is expected as a non-destructive inspection to determine the creep damage level for the turbine blade.
2009-10-21