A Ti-47at%Al alloy, and 3 samples of TiAl which contained some 2.0at%Mn or 0.4at%Si, were prepared by using powder metallurgical techniques. When the samples were irradiated with He ions to 3dpa at 773K, the formation of defect clusters and cavities in TiAl alloys were found to be markedly suppressed by the addition of Mn. In Mn-containing TiAl, the loops which were observed in pure TiAl and Si-containing samples were absent, but defect clusters with large strain fields were found. It was suggested that the defect clusters formed via the migration of mixed dumb-bell type Mn interstitials. The addition of Si had no beneficial effects upon the suppression of radiation damage in TiAl.

Effects of Mn and Si Additions on Microstructural Development in TiAl Intermetallic Compounds Irradiated with He Ions. O.Okada, K.Nakata, K.Fukai, A.Hishinuma, K.Ameyama: Journal of Nuclear Materials, 1998, 258-263, 1750-5