Effect of aging heat treatment on microstructure of Ni-based single crystal superalloys

The precipitation and evolution of γ′ precipitates for various aging heat treatment regimes are studied experimentally in Ni-based single crystal superalloys for both standard heat treatment and long-term aging samples. The focus of this paper is to explore the influence of aging heat treatment on the evolution of the morphology and the distribution of γ′ precipitates. It is demonstrated that the splitting and shrinkage phenomena appear at low aging heat treatment temperatures, and the passivation phenomenon occurs at a high aging temperature of 1200°C. The uniform cubic γ′ particles can be obtained at 1100°C/4 h for the standard heat treatment samples and 1150°C/8 h for the long-term aging ones. This research is beneficial for the study of the rejuvenation aging heat treatment in re-service nickel-based superalloys.