Influence of cooling rate on microstructure formation during rapid solidification of binary TiAl alloys

•Rapid solidification studies with varying cooling rates were realized for Ti–Al.•Experiments were combined with finite element simulations of heat transfer.•The resulting microstructure of Ti–Al alloys is strongly dependent on the Al content.•The microstructure and phase transformation behavior can be predicted.•The method allows alloy development for processes involving rapid solidification.

Titanium aluminides as structural intermetallics are possible candidates for a potential weight reduction and increased performance of high temperature components. A method for the characterization of the microstructure formation in rapidly solidified alloys was developed and applied for binary Ti–(44–48)Al (at.%). The results show a strong dependency of the microstructure on the Al content at cooling rates between 6 ⋅ 102 and 1.5 ⋅ 104 K s−1. The formation of α → α2 ordering, lamellar α2 + γ colonies and interdendritic TiAl γ-phase were observed, depending on the Al amount. Based on thermodynamic calculations the observed microstructure can be explained using the CALPHAD approach taking into account the non-equilibrium conditions. The presented method provides a useful tool for alloy development for processing techniques involving rapid solidification with varying cooling rates.