Solidification behaviour of TiAl-based alloys studied by directional solidification technique

Solidification behaviour of TiAl-based alloys with the nominal chemical composition Ti–46Al–8Ta and Ti–46Al–8Nb (at.%) was studied at steady- and unsteady-state conditions in Y2O3 moulds using Bridgman solidification technique. The effect of growth parameters (growth rate V and temperature gradient GL) on primary solidification phase, solidification path and microstructure parameters were determined. Directional solidification at unsteady-state conditions was applied to determine columnar to equiaxed transition (CET) in the studied systems.

► The solidification path and high temperature phase equilibria are determined for the intermetallic Ti–46Al–8Ta and Ti–46Al–8Nb (at.%) alloys.
►  The effect of growth parameters on columnar dendritic growth and microstructural parameters is defined.
► The columnar to equiaxed transition (CET) diagram is determined experimentally for the Ti–46Al–8Nb alloy and compared with available data of other alloys.