Hardening effects of He irradiation on Fe-Cu alloy

To study the effects of ion irradiation on hardening and microstructural evolution of solute clusters in Fe-based alloys, Fe-Cu alloy was irradiated with 2.0 MeV He ions to a fluence of 1.0 x 10(17) ions cm(-2) at 563 K. Nanoindentation and atom probe tomography (APT) were used to characterize the hardness and solute distributions, respectively. Correlation between the mechanical property and microstructure was also discussed. Nanoindentation results showed that the irradiation-induced hardening quickly increased as irradiation depth/damage increased at first and then slowly reached saturation at shallower depth. APT results also showed that well-defined Cu clusters were precipitated after irradiation and grown to a clear saturation at about 0.05 dpa, but the precipitation was suppressed slightly at higher damage/damage rate due to cascade mixing. The good agreement between calculated strength and measured strength demonstrates that the Cu culsters are the dominant feature for hardening.