In Situ Microtensile Testing for Ion Beam Irradiated Materials
Understanding the changes in mechanical properties and failure mechanisms as a function of radiation damage is important for long-term operation of structural components in nuclear reactors. Due to the expense, the activation of the sample, and the long duration of neutron irradiation, ion beam irradiations (proton-irradiation and, increasingly, heavy-ion irradiation) are used as surrogates for neutron irradiation. However, the shallow irradiation depths of ion-beam irradiation have restricted mechanical property measurements until the recent advent of small-scale mechanical testing. In previous studies, nano-hardness and yield strength of proton-irradiated 304SS were measured using nanoindentation and in situ microcompression respectively. This study develops an in situ microtensile testing method to provide direct stress-strain curves, including the strain to failure, which previous studies do not provide. In addition, a novel way of quantifying irradiation-induced susceptibility to slip band formation in microscale specimens was demonstrated. Lastly, the paper introduces a new technique for measuring grain boundary strength, demonstrated on an oxidized grain boundary of Alloy 600 exposed to primary water chemistry environment.
KeywordsRadiation damage Micro-tensile testing Yield strength Total elongation Stainless steel Localized deformation Slip band Primary water chemistry Stress corrosion cracking
The authors thank the Biomelecular Nanotechnology Center (BNC) at the University of California, Berkeley for providing access to its FIB instrument and the Electric Power Research Institute for funding this research.
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