Microstructural stability of the intermetallic Ti–45Al–2W–0.5Si–0.5B in the 800–980 °C temperature range

γ-TiAl intermetallic Ti–45Al–2W–0.5Si–0.5B was exposed in the temperature range of 800–980 °C, well over its intended application range, for up to 1000 h to test its thermal stability limit. It was found that, the fine α2 laths could be broken down by growth of equiaxed γ grains, transformation of α2 to B2 phase, and coalescence of α2 laths. With increasing of temperature, needle-like B2 phase became spheral, and its volume fraction increased due to the transformation of α2 to B2 phase. Addition of boron was demonstrated to be beneficial to the thermal stability of the lamellar structure, by the way of comparison to its boron-free counterpart ABB-2 alloy. Subsurface evolution during long-term aging was also investigated.