Investigation on microstructure evolution of a new disk superalloy under different hot process

Abstract

Over the course of this paper, a FGH100L nickel based alloy, which was prepared by spray forming, had been treated by hot isostatic pressing, followed by an optimized heat treatment. The microstructure evolution of gamma prime phase under different conditions was systematically analyzed. In conclusion, both the temperature and cooling rate during the heat treatment can affect gamma prime phase on its morphology, size and distribution. By varying solution treatment temperature, size variation of γ′ phase and fine-grain microstructure was obtained at a relatively low solution treatment temperature. As for changing cooling rate, a doublet morphology of splitting γ′ phase appeared at a relatively slow cooling rate under hot isostatic pressing progress. Based on microstructural characterization of γ′ phase, the reasonable heat treatment regime of FGH100L alloy was determined. The deformation recrystallization occurred when the as-deposited alloy was treated by hot isostatic pressing, which results in grain morphology changing from spherical or sphere-like to polygon. It can be obtained multi-sized γ′ precipitates for the hot isostatic pressing alloy which treated by optimized heat treatment regime. The results indicate that the multi-sized γ′ phase microstructure is beneficial to obtain ideal comprehensive mechanical properties.