Abstract
This study investigated the elevated temperature properties and creep behavior of Y2O3-bearing Ti-48Al-6Nb alloy. Tensile and creep tests of Ti-48Al-6Nb and Ti-48Al-6Nb-0.05Y2O3 alloys were performed. The results show that the brittle-ductile transition temperatures (BDTTs) of both alloys are determined to be 825–850 ℃ by tensile tests at the strain rate of 5 × 10−4 s−1. And the BDTTs of both alloys are determined to be 800–825 ℃ by creep tests under a constant stress of 325 MPa, reducing about 25 ℃ due to the slower creep rates. Y2O3 improves the creep properties of the alloys by refining α2/γ lamellar spacing, decreasing segregation and preventing dislocation movement. Furthermore, creep deformation behavior of α2 phases at the BDTT was discussed. Deformation of α2 laths during creep is mainly provided by a→ type dislocations below the BDTT. While above the BDTT, 2c→+a→ type dislocations were activated due to the active thermal activation and decreasing Peierls-Nabarro stress. The presence of 2c→+a→ slip systems in α2 laths contributes to ductile deformation during creep.
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