The formation of Cu precipitates in Fe-1wt%Cu alloy specimens, as enhanced by deformation, was studied by using positron annihilation techniques, coincidence Doppler broadening and the positron lifetime method. In specimens which had been quenched, and rolled by 20% at room temperature, formation of Cu-vacancy clusters was observed; which explained the enhanced diffusion of Cu atoms by deformation-induced excess vacancies which were mobile at room temperature. By annealing at up to 400C following deformation, vacancies and vacancy clusters were dissociated from the Cu-vacancy clusters, and from ultra-fine Cu precipitates which were coherent with the Fe matrix.

Deformation-Enhanced Cu Precipitation in Fe-Cu Alloy Studied by Positron Annihilation Spectroscopy. T.Onitsuka, M.Takenaka, E.Kuramoto, Y.Nagai, M.Hasegawa: Physical Review B, 2002, 65[1], 012204 (4pp)