Migration behaviour of vacancies and damage structure recovery in a Fe-based Fe-Cr-Mn-Cu-Mo multi-component alloy.

A Fe-based multi-component alloy, 60Fe-12Cr-10Mn-15Cu-3Mo, which presents higher yield stress than typical stainless steels (such as 304, 316, and 340), was used to investigate the thermal stability of irradiation-induced defects. Neutron irradiation was carried out at approximately 323 and 643 K using up to 1.3 × 10⁻³ and 4.5 × 10⁻⁴ dpa (displacements per atom), respectively. While no defects were accumulated at the high temperature of 643 K, single vacancies were formed after irradiation at the low temperature of 323 K to 1.3 × 10⁻³ dpa, and the vacancies became mobile at 423 K. As a result, vacancy clusters were formed. However, as the annealing temperature increased the size of vacancy clusters decreased. Coincidence Doppler broadening measurements indicated that Cu precipitates were the sites of vacancy cluster formation, and the recovery of vacancy clusters became prominent while annealing the irradiated sample at temperatures higher than 423 K. Recovery of vacancy clusters at 573 K, which was not a high temperature, was also observed even in the sample that was irradiated using 2.5 MeV Fe ions at room temperature to 0.6 dpa at damage peak. [ABSTRACT FROM AUTHOR]