The influence of high-temperature oxidation resistant titanium aluminide coating on low-cycle fatigue behaviour of titanium alloy IMI 834 at 600 °C

Abstract

The low-cycle fatigue behaviour of titanium alloy IMI 834 was comparatively studied in bare condition and with titanium aluminide (Al₂Ti) coating at 600 °C in air. Results revealed that at higher values of total strain amplitudes (Δε_t/2), Al₂Ti-coated IMI 834 alloy has longer fatigue life (N_f) compared to the bare IMI 834 alloy, which appears to be due to load shifting to the coat. At lower values of Δε_t/2, Al₂Ti coating on IMI 834 alloy seems to have no effect on N_f. Higher values of cyclic strength coefficient (K′) and cyclic hardening exponent (n′) for coated IMI 834 alloy indicate that coating offers resistance to cyclic plastic deformation at 600 °C in air, and hence it is beneficial. The coating adheres well to the substrate and is also fairly resistant to high-temperature corrosion in sea water atmosphere at 600 °C.