Evolutions of microstructure, phase, microhardness, and residual stress of multiple laser shock peened Ni-based single crystal superalloy after short-term thermal exposure

In this work, evolutions of microstructure, phase, microhardness, and residual stress of multiple laser shock peened (LSP) Ni-based single crystal (SC) superalloy after short-term thermal exposure for 1 h at 950 degrees C and 1200 degrees C were investigated. The results showed that slipping systems of {1 1 1} <1 1 0> were activated by multiple LSP in [3 1 1] orientation, which resulted in the formation of dislocation slip bands along (1 (1) over bar 1) plane. The dislocation structures induced by LSP in gamma and gamma' phases had a vital influence on the lattice misfits of two phases as compared to the composition changes of gamma phase, which led to increased lattice misfits. Moreover, the decrease in microhardness and residual stress after thermal exposure was attributed to the decrease in dislocation density due to dislocation annihilation.