Observations of defect structure evolution in proton and Ni ion irradiated Ni-Cr binary alloys

Two binary Ni-Cr model alloys with 5 wt% Cr and 18 wt% Cr were irradiated using 2 MeV protons at 400 and 500 degrees C and 20 MeV Ni4+ ions at 500 degrees C to investigate microstructural evolution as a function of composition, irradiation temperature, and irradiating ion species. Transmission electron microscopy (TEM) was applied to study irradiation-induced void and faulted Frank loops microstructures. Irradiations at 500 degrees C were shown to generate decreased densities of larger defects, likely due to increased barriers to defect nucleation as compared to 400 degrees C irradiations. Heavy ion irradiation resulted in a larger density of smaller voids when compared to proton irradiations, indicating in-cascade clustering of point defects. Cluster dynamics simulations were in good agreement with the experimental findings, suggesting that increases in Cr content lead to an increase in interstitial binding energy, leading to higher densities of smaller dislocation loops in the Ni-18Cr alloy as compared to the Ni-5Cr alloy. (C) 2016 Elsevier B.V. All rights reserved.