VOID FORMATION AND SOLUTE SEGREGATION IN TI-14.4 AT PERCENT-AL

An alloy of Ti-14.4 at% Al was irradiated with 3.0 MeV 58Ni ions at temperatures near 600°C and to damage levels from 1.3 to 14.7 dpa. TEM examination of these specimens showed the damage produced voids, dislocation loops and network dislocations. The undersize aluminum solute atom segregated to the voids, grain boundaries and the irradiated surface, causing enhanced precipitation of γ'-Ti3Al at these sinks for point defects. Shells of α2 ~ 75 A ̊ thick coated the voids and a continuous film of γ' was observed on the irradiated surface and on some grain boundaries. The surface film of α2 contained 1 3a 〈11 2 ̄0〉 antiphase boundaries. Voids have not been previously observed in irradiated hcp Ti and this is the first observation of substantial irradiation-induced segregation in an hcp alloy. © 1979.