Microstructural degradation after thermal exposure of a Re-containing single crystal superalloy

Abstract

Microstructural degradation after thermal exposure of a 5% Re -containing single crystal (SX) superalloys has been studied. The alloy was subjected to thermal exposure at temperature of 1100 °C for periods of 100, 500, and 1000 h. The microstructure of the alloy was degraded after long-term thermal exposure, mainly in γ' coarsening, the precipitation topologically close packed (TCP) phases. Moreover, the stress-rupture properties of the samples before and after long-term thermal exposures were characterized. The results showed that the γ' coarsening and TCP formation after exposed for 500 h, which led to a damaged of the stress-rupture life time. Besides, the growth of pores during exposure also influences the stress-rupture life. • γ' coarsening and TCP phase precipitation are characterized after long-term exposure. • The TCP phase does not embrittle the alloy. • The severe γ' coarsening is the main factor in the degradation of the life time.