Void formation and solute segregation in ion-irradiated niobium-base alloys

The void-volume fraction in unalloyed Nb and Nb-base binary alloys containing either approx. 2.4 a/o Mo, Ti, Zr, Hf, Ni, Fe, V, or Ta has been determined following 3.0-MeV /sup 58/Ni/sup +/ ion irradiation at 1225 K to approx. 50 dpa. also, the thermal- and irradiation-induced segregation of these substitutional-atom solutes and the intrinsic, interstitial-O impurity (approx. 0.06 a/o) to the specimen surface and within the irradiation-damaged layer have been determined. The void-volume fraction and the segregation of solutes have been shown to be correlated by the solute diffusivity and the relative chemical affinity of the substitutional solutes for O. The correlated diffusion of vacancy defects and O atoms is postulated to explain the experimental results.