EFFECTS OF MA AND SI ADDITIONS ON MICROSTRUCTURAL DEVELOPMENT IN TIALINTERMETALLIC COMPOUNDS IRRADIATED WITH HE-IONS

A Ti-47 at.% Al intermetallic alloy and three TiAl alloys containing s imilar to 2.0 at.% Mn and/or similar to 0.4 at.% Si were prepared by p owder metallurgical processing. When the samples were irradiated with Ne-ions to 3 dpa at 773 K, formation : of defect clusters and cavities in TiAl alloys were remarkably suppressed by the addition of Mn. In M n-added TiAl, although no loops, which were observed in pure TiAl and Si-added samples, were formed, the defect clusters with large strain f ield were found. It was suggested that the defect clusters were formed by the migration of mixed dumbbell type Mn atom-interstitials. The ad dition of Si showed no beneficial effects on suppression of radiation damage in TiAl alloys. (C) 1998 Elsevier Science B.V. All rights reser ved.