Elevated temperature performance and creep behavior of Y2O3 reinforced Ti-48Al-6Nb alloy at the brittle-ductile transition temperature

This study investigated the elevated temperature properties and creep behavior of Y2O3-bearing Ti-48Al6Nb alloy. Tensile and creep tests of Ti-48Al-6Nb and Ti-48Al-6Nb-0.05Y(2)O(3) alloys were performed. The results show that the brittle-ductile transition temperatures (BDTTs) of both alloys are determined to be 825-850 degrees C by tensile tests at the strain rate of 5 x 10(-4) s(-1). And the BDTTs of both alloys are determined to be 800-825 degrees C by creep tests under a constant stress of 325 MPa, reducing about 25 degrees C due to the slower creep rates. Y2O3 improves the creep properties of the alloys by refining alpha(2)/gamma lamellar spacing, decreasing segregation and preventing dislocation movement. Furthermore, creep deformation behavior of alpha(2) phases at the BDTT was discussed. Deformation of alpha(2) laths during creep is mainly provided by a type dislocations below the BDTT. While above the BDTT, 2 (c) over right arrow + (a) over right arrow type dislocations were activated due to the active thermal activation and decreasing Peierls-Nabarro stress. The presence of 2 (c) over right arrow + (a) over right arrow slip systems in alpha 2 laths contributes to ductile deformation during creep. (C) 2021 Elsevier B.V. All rights reserved.