41.5Ni-40Fe-16Cr-2.9Nb-1.8Ti-0.2Al 合金におけるγ′相とγ″相の析出と成長

概要

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A 41.5Ni-40Fe-16Cr-2.9Nb-1.8Ti-0.2Al alloy is a superalloy strengthened by the precipitation of γ′and γ″phases. The knowledge of the nucleation and growth behaviors of the γ′and γ″precipitates is very important for a appropriate usage of the alloy. We investigated the precipitation characteristics of this alloy by micro-Vickers hardness test, X-ray diffraction and transmission electron microscopy. The hardness of the alloy aged in various conditions closely related to the size of the γ′and γ″precipitates. With increasing aging time, the lattice parameter of the alloy matrix decreases and reaches a constant value at each aging temperature after a certain aging time. The volume fractions of γ′and γ″phases precipitated in the alloy at 993K are 7.2% and 13.3%. respectively. The growth kinetics of the γ′and γ″precipitates followed the predictions of LSW theory of diffusion controlled growth at all aging temperatures. The activation energy values for the growth of γ′and γ″precipitates are estimated to be 278kJ/mol and 431kJ/mol, respectively. Some γ″precipitates contain γ′precipitates inside their bodies or are in contact with the γ′precipitates. It is considered that some γ′precipitates of this alloy act as preferential nucleation sites for the γ″precipitates.
社団法人日本鉄鋼協会の論文
1998-09-01