High-temperature deformation resistance and creep resistance of a TiAl-based alloy fabricated by cold crucible directional solidification technology

In order to improve the high-temperature deformation resistance and creep resistance of TiAl-based alloys, cold crucible directional solidification (CCDS) technology was employed. A β-type TiAl-based alloy with the nominal composition of Ti44Al6Nb1Cr2V was prepared using the optimized CCDS parameters of 45 kW input power and 0.5 mm·min⁻¹ solidification rate. Thermo-compression testing was utilized to evaluate the high-temperature deformation resistance and creep resistance of the CCDS Ti44Al6Nb1Cr2V alloy. Results show that the CCDS Ti44Al6Nb1Cr2V alloy billets contain aligned columnar grains and a high percentage of small-angle lamellae. Thermo-compression testing results in the radial direction of the CCDS alloy show a much higher peak stress than other reported results in similar conditions. The much higher hardening exponent and deformation activation energy are obtained, corresponding to the excellent high-temperature deformation resistance and creep resistance, which are because of the hard-oriented grains, weaker stress-strain coordination capability of lamella structure and relatively more hysteretic dynamic recrystallization. Thermo-compression testing results in the longitudinal direction of the CCDS Ti44Al6Nb1Cr2V alloy show the much higher peak stress than that in the radial direction, indicating the better high-temperature deformation resistance and creep resistance attributed to the hard-oriented lamellae in this condition.