Microstructure evolution and deformation features of single crystal nickel-based superalloy containing 4.2% Re during creep

Abstract

By means of microstructure observation and measurement of creep properties, the high temperature creep behaviors of a single crystal nickel-based superalloy containing Re were investigated. Results show that the single crystal nickel-based superalloy containing 4.2% Re possesses a better creep resistance at high temperature. After being crept up to fracture, the various morphologies are displayed in the different areas of the sample, and the γ′ phase is transformed into the rafted structure along the direction vertical to the applied stress axis in the regions far from the fracture. But the coarsening and twisting extents of the rafted γ′ phase increase in the regions near the fracture, which is attributed to the occurrence of the larger plastic deformation. In the later stage of creep, the deformation mechanism of the alloy is that the dislocations with [ 0 1 ¯ 1 ] and [011] trace features shear into the rafted γ′ phase. The main/secondary slipping dislocations are alternately activated to twist the rafted γ′ phase up to the occurrence of creep fracture, which is thought to be the fracture mechanism of the alloy during creep.