Abstract
Chi-phase precipitation was observed by transmission-electron microscopy (TEM) in Mo-30at.%Re and Me-27at.%Re specimens that had been irradiated with 1·8 MeV He ions at temperatures from 750°C to 1075°C. The precipitates formed at the rhenium-rich external surface and adopted both parallel and (111) twin orientations with respect to the matrix. Details of precipitate morphology and crystallogaphic orientation are reported.