Method for Evaluating Irradiation Effects on Flow Stress in Fe-9%Cr ODS Using TEM In Situ Cantilevers

Transmission electron microscopic (TEM) in situ mechanical testing has become a widely utilized tool for simultaneously measuring mechanical properties and understanding fundamental deformation mechanisms in irradiated and nuclear materials. Although tensile and compression specimen geometries are among the most common, opportunities remain for investigating alternative geometries that could provide unique insights into the plasticity of irradiated materials. This work demonstrates a new TEM in situ cantilever beam configuration. Cantilevers are produced from as-received and proton-irradiated (1 dpa, 500°C) Fe-9%Cr oxide dispersion-strengthened steel. Flow stress is measured using a TEM in situ depth-sensing mechanical testing holder. A 200-MPa increase in flow stress is measured due to irradiation. Size effects arise when the intrinsic (i.e., microstructural) size approaches the extrinsic (i.e., external dimensions) size and can be described using a power law relationship as a function of the material microstructure and cantilever dimensions.