High-energy x-ray diffraction microscopy study of deformation microstructures in neutron-irradiated polycrystalline Fe-9%Cr

Abstract In this study, we used far-field high-energy x-ray diffraction microscopy (FF-HEDM) to measure in 3D the spatial distributions of the sizes, orientations, and residual strains of grains and subgrains formed by room-temperature tensile deformation in a neutron-irradiated (450 °C, 0.01dpa) Fe-9Cr specimen and its unirradiated counterpart. We found that neutron irradiation under this condition alone had no effect on the grain size distribution. After deformation, grains fragmented into subgrains in both unirradiated and irradiated specimens: the irradiated specimen contained a few large subgrains which co-existed with many smaller subgrains, while the unirradiated specimen contained small subgrains with a relatively uniform size distribution. Prior to deformation, the irradiated specimen had higher residual strain spread compared to its unirradiated counterpart, while after deformation to the maximum uniform elongation, the strain distributions among subgrains were similar between the unirradiated and irradiated specimens. The FF-HEDM measurements provide new insight into the effects of neutron irradiation on the mechanical response of Fe-Cr ferritic alloys.