Magnetic after-effect study of the Cu-precipitation in thermally aged Fe-1%Cu alloys

A magnetic after-effect setup is developed and used to study the Cu-precipitation process in thermally aged Fe-1%Cu alloys, as a complementary process to the irradiation induced hardening due to Cu-precipitation in iron-based alloys used as structural materials in the nuclear industry. The magnetic relaxation spectra, measured in the temperature region from 200K to 500K, show the existence of two relaxation processes centered at 260K and 330K, which are assigned as the Snoek-carbon relaxation process and thermal activation of dislocation motion, respectively. The behavior of both processes are influenced by copper precipitation. The growth of copper precipitates by increasing the aging time influences the carbon kinetics, which is manifested by a strong decrease of the Snoek peak intensity. On the contrary, the peak intensity related to dislocation relaxation exhibits an increase by increasing the aging time as a consequence of the decrease of Cu-precipitate number density and dislocation pinning.