Formation of Cu precipitates and vacancy clusters in neutron-irradiated Fe-Cu alloys.

Two Fe-Cu binary model alloys, Fe-0.3Cu and Fe-0.6Cu, were irradiated with fission neutrons at doses ranging from 4 × 10-6 to 0.16 dpa (displacements per atom) at ∼573 K to investigate the formation of Cu precipitates and microstructural evolution. The Cu content only affected the formation of Cu precipitates and microvoids at low doses. In Fe-0.3Cu, the formation of microvoids and Cu precipitates initiated at doses of 1.2 × 10-4 and 4 × 10-5 dpa, respectively. On the other hand, the formation of microvoids started at a dose of 4 × 10-4 dpa in Fe-0.6Cu, and Cu precipitates were formed even after irradiation to 4 × 10-6 dpa. On further irradiation, the difference in the formation of Cu precipitates and microvoids was small. Microvoids grew with increasing irradiation dose up to 3 × 10-3 dpa in both alloys. Prominent aggregation of Cu atoms occurred upon irradiation from 3 × 10-3 to 1.6 × 10-2 dpa and the microvoids shrank. The Cu precipitates no longer grew, and microvoids nucleated and grew in the matrix above a dose of 1.6 × 10-2 dpa in both alloys. The present studies clearly reveal the relationships between the formation and growth of Cu precipitates and microvoids with irradiation dose. [ABSTRACT FROM AUTHOR]