Deformation mechanisms and analysis of a single crystal nickel-based superalloy during tensile at room temperature

Abstract

By means of measuring the yield and ultimate tensile strength at room temperature, microstructure observation and contrast analysis of dislocation configuration, the deformation features of a single crystal Ni-based superalloy during tensile are investigated. The results show that the ultimate tensile strength (σb) and yield strength (σ0.2) of the single crystal nickel-based superalloy at room temperature are measured to be 1023 MPa and 958 MPa, respectively. During tensile at RT, the <110> super-dislocations in γ′ phase may decompose on the {111} plane to form only configuration of (1/2)<110> partials plus APB. no configuration of (1/3)<112> partials plus SISF in the alloy is attributed to the dislocation decomposing on {111} plane to form the APB needing a smaller energy than to form the SISF. And the reason of decomposed width with about 20–30 nm keeping in the alloy is attributed to the lower stacking fault energy of alloy and a few deformed heat released during tensile at RT. The <110> super-dislocation in γ′ phase may cross-slip form the {111} to {100} plane to form the K-W locks during tensile at RT, no decomposed feature in K-W locks is attributed to the dislocation decomposing on {100} plane needing a bigger energy. The <110> super-dislocation of shearing into γ′ phase may be also decomposed on the {111} plane to form the Giamei dislocation locks consisting of (1/3)<112> partial loops plus SISF, which is attributed to the combined role of applying a big normal stress and a few deformed heat during tensile.