Hardening of Fe–Cu alloys by swift heavy ion irradiation

Two kinds of model alloys, Fe–0.6 wt.% Cu and Fe–1.2 wt.% Cu, are irradiated with GeV heavy ions at 250 C and at room temperature. Vickers microhardness test at room temperature shows that the change in hardness due to irradiation strongly depends on the irradiation temperature and the copper content. For Fe–1.2 wt.% Cu alloy irradiated at 250 C, the hardness change is much larger than that for 2.5 MeV electron irradiation at the same dpa (displacements per atom through elastic collisions). The experimental result implies that the electronic excitation by GeV ions enhances the copper precipitation. This effect is, however, hardly observed for Fe–0.6 wt.% Cu alloy or for the irradiation at room temperature. 2002 Elsevier Science B.V. All rights reserved.