Effects of cold work prior to aging on microstructure of AEREX™350 superalloy

The influence of different amounts of cold work on the evolution of microstructure during subsequent aging of AEREX™350 superalloy was investigated. Simple compression testing was used to impose desired plastic strain while microhardness testing, XRD, SEM and TEM techniques were used to characterize the response of the alloy following aging treatment. It was found that high levels of cold work followed by aging resulted in a drastic increase in the formation of Widmanstättan η phase and incidence of shear bands in the microstructure. Based on microstructural data, the effect of plastic strain on η phase formation and the physical origin of the localized shear bands are discussed.