A new developed Re-containing β-solidified TiAl alloy with superior strength and plasticity at 800 °C

In this study, the tensile properties of a novel Ti-43Al-1.5Cr-0.5Re Alloy is studied. The near lamellar microstructure was architected through hot-rolling in α + β regio and the alloy sheet exhibited ultra-high tensile strength (≈821 MPa) compared to present TiAl alloys at 800 °C, while an advantaged elongation of 22 % was still maintained. The ultra-high strength in Ti-43Al-1.5Cr-0.5Re attributed to multiple deformation mechanisms: Firstly, the occurrence of novel lamellar kinking induced by α twining facilitated the fragmentation of large lamellar colonies, leading to significant grain refinement strengthening effect. Secondly, the occurrence of Dislocation-Jogged Dislocation (DJD) effect significantly improved the total dislocation density, which brought about remarkable dislocation strengthening effect. Moreover, the presence of discontinuous twin boundaries provides strain gradients that limit overall dislocation motion, thereby enhancing the strength furtherly. This study provides a novel approach for fabricating high-performance TiAl alloy sheets.