Fe-38Ni-13Co-4.7Nb 耐熱合金におけるγ'相の析出と成長

概要

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Fe-38Ni-13Co-4.7Nb base superalloy (alloy 909) is the latest low thermal expansion chromium-free superalloy with a good resistance to SAGBO (Stress Accelerated Grain Boundary Oxidation) embrittlement at elevated temperatures. This investigation was carried out to elucidate the relation between the age-hardening and the nucleation and growth behavior of γ' precipitates in alloy 909 by micro Vickers hardness test and transmission electron microscopy. The results obtained in this study are as follows : (1) The hardness of alloy 909 measured at aging temperatures was ca. HV100 lower than that measured at room temperature. (2) The hardness of specimens aged at 893-1033K for durations up to 720ks closely related to the mean size of γ' precipitates. (3) The growth kinetics of the γ' precipitates in ε phase free region was explained by Lifshitz-Slyozov-Wagner's theory of volume diffusion controlled growth at 943-1033K. The activation energy for the growth of γ' precipitates was estimated to be 254kJ/mol which was nearly equal to those of diffusion of Ti or Fe atoms in γ-iron or nickel.
社団法人日本鉄鋼協会の論文
1993-12-01