Influence of Al content on non-equilibrium solidification behavior of Ni–Al–Ta model single crystal alloys

• Solidification paths of five Ni–Al–Ta model single crystal superalloys were studied.
• Liquidus temperature first decreased and then increased with decreasing Al content.
• Microsegregation behavior was studied by experiment and simulation methods.
• The microsegregation of Al had obvious influence on last stage solidification path.

The non-equilibrium solidification behaviors of five Ni–Al–Ta ternary model single crystal alloys with different Al contents were investigated by experimental analysis and theoretical calculation (by JMatPro) in this study. These model alloys respectively represented the γ׳ phase with various volume fractions (100%, 75%, 50%, 25% and 0%) at 900 °C. It was found that with decreasing Al content, liquidus temperature of experimental alloys first decreased and then increased. Meanwhile, the solidification range showed a continued downward trend. In addition, with decreasing Al content, the primary phases of non-equilibrium solidified model alloys gradually transformed from γ׳ phase to γ phase, and the area fraction of which first decreased and then increased. Moreover, the interdendritic/intercellular precipitation of model alloys changed from β phase (for 100% γ׳) to (γ+γ׳)Eutectic (for 75% γ׳), (γ+γ׳)Eutectic+γ׳ (for 50% γ׳ and 25% γ׳) and none interdendritic precipitation (for 0% γ׳), and the last stage non-equilibrium solidification sequence of model alloys was determined by the nominal Al content and different microsegregation behaviors of Al element.