Interstitial solubility in gamma and alpha(2) phases of TiAl-based alloys

Measurements of interstitial concentrations were performed on (alpha(2) + gamma) two-phase TiAl alloys and on gamma single-phase TiAl alloys. This study allowed the determination of the maximum solubility of oxygen and carbon in the gamma phase. The influence on this solubility of various parameters such as temperature, alpha(2) and gamma phase stoichiometry and the alloying addition of a third element will be discussed. This paper also presents an explanation in the higher solubility of oxygen in alpha(2) phase compared to gamma phase. From our results it is shown unambiguously that the better ductility of (alpha(2) + gamma) two-phase alloys can no longer fit with the widespread idea of a scavenging effect of the alpha(2) phase which would lower in that way the interstitial level in gamma phase. Copyright (C) 1996 Acta Metallurgica Inc.