Helium ion irradiation-induced damage of powder metallurgy-hot isostatic pressed Ni-based alloy GH3535 for molten salt reactor applications

Abstract

Powder metallurgy-hot isostatic pressing (PM-HIPing) is a promising technology for the manufacturing of components for nuclear reactors. In this study, Ni-based alloy GH3535 for molten salt reactor applications, was processed via PM-HIPing, and irradiation damage behaviors of the PM-HIPed GH3535 along with its forged counterparts were studied with He+ ions irradiation and microstructural characterization. The irradiation-induced defects in the samples, such as helium bubbles and dislocation loops, were characterized using transmission electron microscope (TEM). The mechanical responses of irradiated specimens were studied by nano-indentation. The results show that the PM-HIPed GH3535 exhibits a comparable irradiation resistance to its forged counterparts. Size of the helium bubbles and dislocation loops are larger for samples irradiated at high temperature than those irradiated at room temperature, irrespective of processing methods. However, number density of these defects is smaller for the high temperature irradiated samples than those irradiated at room temperature, which is particularly evident for the forged sample. The samples show significant hardening after irradiation, evidenced by the nano-indentation hardness test results. The experimental results and the calculations based on dispersed barrier hardening (DBH) model are in general agreement. This study will provide important data to support the application of the PM-HIPed materials or components in the nuclear reactors.