In order to study the effect of He atoms upon the formation and annealing of defect clusters, a 47at%Al intermetallic compound was electron-irradiated and bombarded with He ions. It was found that the He-ion bombardment enhanced the nucleation of defect clusters (especially interstitial loops), at temperatures ranging from 623 to 773K, in both -TiAl and 2-Ti3Al grains of the sample. However, there was little difference between the annealing temperature ranges of the defect clusters, in TiAl grains, which had been formed by He ion-bombardment or electron irradiation at 623K. The dot-like clusters and interstitial loops hardly grew during annealing, but were annihilated during annealing at up to 923K. Cavities were formed, after bombardment with He ions to less than 10dpa at 773K, but no cavities were formed by electron irradiation to up to 30dpa. The cavities in both types of grain survived annealing at 1053K for 0.5h, with their number density and diameter being nearly the same as in as-irradiated grains.

K.Nakata, K.Fukai, A.Hishinuma, K.Ameyama: Journal of Nuclear Materials, 1997, 240[3], 221-8