Modeling tensile response and flow localization effects in selected copper alloys

Radiation-induced defect structures are known to elevate material yield strength and reduce material ductility. Together, these changes substantially reduce uniform elongation compared to the unirradiated material condition so that the small strains induce plastic instability. This process, commonly known as flow localization, is examined here for selected copper alloys and compared to similar response in 316SS. It is found that uniform elongation levels are limited by a critical material strength which is independent of the irradiation damage state. This result establishes that the details of the post-yield flow and strain hardening processes are less important than the critical stress for controlling plastic instability. In the case of OFHC Cu, post-irradiation heat treatment restores some initial ductility, but also reduces the critical stress for incipient flow localization.