Xe Ion Irradiation-Induced Microstructural Evolution and Hardening Effect of Nickel-Base Superalloy

The nickel-base superalloy Hastelloy N was irradiated using 1 MeV Xe20+ and 7 MeV Xe26+ ions with displacement damage ranging from 0.5 dPa to 10 dPa at room temperature (RT). The irradiated Ni-based superalloy was characterized with transmission electron microscopy (TEM), XRD, and nanoindenter to determine the changes in microstructural evolution and nanoindentation hardness. The TEM results showed that ion irradiation induced a large number of defects such as black spots and corrugated structures and the second phase was rapidly amorphized after being irradiated to a fluence of 0.5 dPa. The XRD results showed that the Hastelloy N alloy sample did not undergo lattice distortion after ion irradiation. An obvious irradiation hardening phenomenon was observed in this study, and the hardness increased with Xe ion fluence. The pinning effect in which the defects can become obstacles to the free movement of dislocation may be responsible for the irradiation-induced hardening.