Ni 基超合金の高温クリープにおけるγ′相による粒界析出強化

概要

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The creep resistance of Nimonic 80A subjected to prior aging at 1273K for various periods of time between 30 and 3000h was measured by a constant stress creep test at 1273K-49MPa, to confirm the existence of a so-called grain boundary precipitation strengthening due to γ′phase. The minimum creep rate increased with prior aging time : from 3.1×10^<-2>h^<-1> for 30h aging to 1.1×10^<-1>h^<-1> for 3000h aging. This increase in the minimum creep rate could not be correlated with a decrease in a density of intragranular precipitates of γ′phase. The minimum creep rate had a good correlation with the grain boundary area fraction covered with intergranular precipitates of γ′phase. The ratios of the minimum creep rate of the speciments subjected to prior aging to that of an idealized specimen without any intergranular precipitate were equal to the free grain boundary area fraction from the intergranular precipitates of γ′phase. This confirms the intergranular precipitation strengthening previously found in Ni-Cr-W based alloys due to α_2-W precipitates (T. MATSUO et al. : J. Mater. Sci., 22 (1987), p. 1901).
社団法人日本鉄鋼協会の論文
1990-05-01