Local softening behavior accompanied by dislocation multiplication accelerates the failure of Ti-6Al-2Sn-4Zr-2Mo-0.1Si alloy under dwell fatigue load

摘要

In the present study, the dislocation characteristics and stress-strain curves of Ti-6Al-2Sn-4Zr-2Mo-0.1Si (Ti6242s) alloy under low-cycle fatigue and dwell fatigue at room temperature were analyzed. Ti6242s alloy exhibited local softening behavior under cyclic fatigue load as the dislocation density increased. The dislocation morphology showed that a large number of banded dislocations formed in the primary alpha-phase, which were not hampered by grain boundaries, phase boundaries, and other dislocations. The dislocation mobility difference in multiphase microstructure further enhanced inhomogeneous plastic deformation in local areas, which had a negative effect on the failure behavior of Ti6242s alloy under dwell fatigue. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.