Development and testing of microcompression for post irradiation characterization of ODS steels

For decades, the nuclear materials community has been interested in smaller tests for obvious benefits like in limited space or reduction in activity. In this work, we are presenting micropillar tests on ODS steel with a grain size of ∼450 nm and finely distributed oxides as a part of an attempt to use this method in evaluating the change in mechanical properties of nuclear materials after irradiation. Systematic works combining microcompression tests and TEM observations showed that there is no significant size effect on the measured strengths and the dislocation structures of the ODS alloy down to a pillar size of 1 μm. We used both circular and square pillars and discuss the effect of pillar geometry with the evaluated strength and errors. The measured strengths at half the pillar height were found to be in good agreement with the bulk strength measured from a miniature tensile test. The cross-sectional TEM observation of the deformed pillar showed that oxide particles act as strong internal constraining sources for dislocation movement and the formation of dislocation structure.