Microstructural evolution and hardening of GH3535 alloy under energetic Xe ion irradiation at room temperature and 650 °C

The GH3535 alloy was irradiated with 7 MeV Xe26+ ions to a dose of 10 dpa at room temperature (RT) and 650 degrees C, and subsequently examined using Transmission Electron Microscopy (TEM) and nanoindentation. High numbers of nano-sized black dots, identified as dislocation loops were observed in both irradiated samples. The dislocation loops detected at the high temperature irradiated sample (size/number density: 9.5 nm/1.9 x 10(21) m(-3)) were found to be larger in size but less in amount as compared to that of the case of RT irradiation (6.9 nm/18.7 x 10(21) m(-3)). In addition, the large-sized Mo-Cr rich precipitates (16.4 nm/3.7 x 10(21) m(-3)) were observed in the sample irradiated at 650 degrees C. Moreover, the Xe bubbles, with smaller size (2.9 nm) but higher number density (77.8 x 10(21) m(-3)) among the irradiated induced defects, were also detected in the case of high temperature irradiated sample via the diffusion and aggregation of Xe atoms. Nanoindentaion measurements showed a hardening phenomenon for the irradiated sample, and the hardness increment is higher in the case of high temperature irradiated sample. Dispersed barrier-hardening (DBH) model was applied to predict the hardening produced from the irradiation induced defects. The yield strength increment calculated based on TEM observations and the nanohardness increment measured using nanoindentation are in excellent agreement. (C) 2017 Elsevier B.V. All rights reserved.