Effect of high-temperature oxidation on mechanical properties of TC11 titanium alloy

This study systematically investigates the synergistic effects of high-temperature oxidation and subsequent high-cycle fatigue behavior on TC11 titanium alloy (Ti-6.5Al-3.1Mo-1.05Zr-0.35Si, wt%). Comparative analysis shows that exposure to high-temperature oxidation (at 500 °C/10 h) induces a reduction in yield strength and a decrease in fatigue life. Microstructural characterization reveals a critical transition in fatigue failure mechanisms: pristine specimens exhibit conventional surface crack initiation with transgranular propagation, whereas oxidized counterparts develop brittle oxygen-enriched layers that trigger interfacial delamination and accelerated crack growth. The embrittled oxide/matrix interface serves as a preferential site for stress concentration, accounting for the observed increase in fatigue crack propagation rate. These findings provide mechanistic insights into the degradation pathways of titanium alloys under thermo-mechanical coupling conditions, providing guidance for durability assessment and fatigue-resistant design in high-temperature aerospace applications.