Damage mechanisms and embrittlement kinetics in a β-rich Ti 17 alloy after long term aging

Abstract

The Ti 17 (Ti-5Al-2Sn-2Zr-4Mo-4Cr) alloy is used in the first stages of engine compressors, at temperatures up to 450°C. However, its use in structural parts such as engine pylons is more prospective and raises the question of damage tolerance. As the engine pylon environment involves prolonged exposures to high temperatures, the impact of aging on mechanical properties has also to be taken in account. In this work, the consequences of a long-term aging (up to 10 000 h at 450°C) on the mechanical resistance of a Ti 17 alloy are examined at different scales, from macroscopic fatigue crack growth tests to in-situ tensile tests performed on micro samples in a SEM. The detrimental effect of aging on the mechanical properties of the Ti 17 alloy was then discussed in the light of damage mechanisms analysis and embrittlement kinetics.