Does the decoration of irradiation defects induce hardening?

Nano-sized irradiation defects are widely observed to aggregate and decorate the dislocation lines, which is believed to induce irradiation hardening and is mainly described by the cascade-induced source hardening model. In the current work, we demonstrate that dislocation decorated by sessile irradiation defects leads to hardening, which agrees well with the theoretical model prediction. However, no hardening or even softening is observed if the decorated irradiation defects are glissile. The reason for this observation is that the glissile irradiation loops move coordinated to the moving dislocation, and keep in the region where the interaction force between the irradiation defects and dislocation is zero. This work leads to a new understanding of irradiation defect decoration effect and irradiation hardening.