Published online by Cambridge University Press: 26 February 2011
The effect of hydrogen on the phase stability of γ-TiAl and α2-Ti3Al phases was studied, with emphasis on the investigation of decomposition of a metastable α2 phase to a stable γ phase in gamma alloy powders. In this work, progressive decomposition of α2 → γ was observed to occur during aging with increasing temperatures or time under vacuum and under H2. The microstructural analysis indicated that hydrogen may facilitate such decomposition to occur at lower temperatures and shorter aging time.