Measurements of interstitial concentrations were performed on (α2 + γ) two-phase TiAl alloys and on γ single-phase TiAl alloys. This study allowed the determination of the maximum solubility of oxygen and carbon in the γ phase. The influence on this solubility of various parameters such as temperature, α2 and γ phase stoichiometry and the alloying addition of a third element will be discussed. This paper also presents an explanation for the higher solubility of oxygen in α2 phase compared to γ phase. From our results it is shown unambiguously that the better ductility of (α2 + γ) two-phase alloys can no longer fit with the widespread idea of a scavenging effect of the α2 phase which would lower in that way the interstitial level in γ phase.
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