In-situ observation of solidification process in β-solidifying γ-TiAl-based alloy

•Peritectic solidification of a binary β-solidifying γ-TiAl alloy, Ti-40Al, was in-situ investigated.•The formation of peritectic α phase in Ti-40Al alloy solidification is attributed to Al segregation at low cooling rates.•The peritectic α phase forms in TNM alloy due to Al segregation during directional solidification at 5 μm/s. The solidification process of Ti-40Al alloy, a representative β-solidifying γ-TiAl-based alloy, is investigated in-situ using high-temperature laser scanning confocal microscopy (HTLSCM). During the heating process, Ti-40Al alloy exhibits a complete β phase microstructure; however, peritectic α phase is observed during solidification. The occurrence of peritectic α phase is discussed and attributed to the segregation of Al under certain solidification conditions. This finding is further confirmed in the directional solidification of another β-solidifying γ-TiAl-based alloy, TNM alloy, and it provides valuable guidance for controlling the microstructure of β-solidifying γ-TiAl-based alloys.