The stability of gamma ' precipitates in a multi-component FeCoNiCrTi0.2 alloy under elevated-temperature irradiation

摘要

Precipitation hardening by gamma' precipitates is an effective strengthening mechanism for designing novel high-entropy alloys (HEAs). The stability of these gamma' precipitates under elevated temperature irradiation is a major concern for their application in nuclear industry. In the present study, a gamma'-strengthened FeCoNiCrTi0.2 HEA is irradiated using 6.4 MeV Fe3+ ions at 400 degrees C, 500 degrees C and 600 degrees C, respectively. After irradiation, transmission electron microscopy (TEM) and atom probe tomography (APT) has characterized the structural and compositional stability of the gamma' precipitates. The results show that the ordered L1(2) structure of gamma' precipitate is susceptible to the radiation damage, whereas their basic compositional features can sustain up to similar to 13 dpa at these temperatures. APT reveals that the dissolution of gamma' precipitates start from the surface of the precipitates at the early stage of irradiation. Dissolution and disordering of the precipitates are dependent on the irradiation dose and temperature. APT also shows that small Ni and Ti-rich clusters form after irradiation at elevated temperatures. The behavior of gamma' precipitates under irradiation is believed to be controlled by two competing factors, displacement damage and radiation enhanced diffusion. Both can influence the radiation induced disordering/dissolution and rep recipitation. (C) 2020 Published by Elsevier B.V.