Characterization of microstructure and microhardness of Neutron irradiated Inconel X-750

Abstract

In this study, we characterized the microstructure evolution and hardness of Inconel X-750 samples that were irradiated in-reactor at several different dose rates and temperatures and at doses up to 84 dpa. The irradiation induced lattice defects, the stability of γ’ precipitates, and the formation of helium bubbles were studied. Detailed statistics regarding the size and density of those features were obtained. The combined effects from irradiation dose, dose rate, and temperature on the disordering and dissolution of precipitates and the formation of bubbles were discussed. The isolated contributions of those microstructural features to the total material strength were calculated based on the Dispersed Barrier Hardening (DBH) model. The spatial distribution of He bubbles, especially the visible large ones (>2 nm), were also found to either correlate or anti-correlate with the spatial distribution of solute elements, e.g., Ti, Fe, and Cr, at doses higher than 75 dpa.