Evolution of Surface Morphology of Oxide Formed During Initial-Stage Oxidation of γ-TiAl Alloy Using In Situ Environmental SEM

Initial-stage oxidation characteristics of a γ-TiAl alloy were investigated by using in situ environmental scanning electron microscopy for both heating and isothermal oxidation processes. Selective oxidation led to primary nucleation and growth on the aluminum-rich γ phase. Under different isothermal oxidation times, the oxide morphology changed to a linear structure between 750 °C and 774 °C and to an acicular structure at 800 °C. The initial oxidation process of γ-TiAl alloy could be divided into three stages: nucleation; growth; and morphological transformation and subsequent growth stages.