Achieving superior tribological resistance of Ti-6Al-4 V alloy via femtosecond laser shock peening

Ti-6Al-4 V alloy employed as compressor blade is commonly vulnerable to elevated temperature wear damage during service. To ensure longevity, substantial surface modification techniques have been developed, with femtosecond laser shock peening (FLSP) garnering significant attention owing to ultra-high strain rate and flexible controllability. This study systematically investigated the high temperature wear behavior of Ti-6Al-4 V subjected to FLSP through multiscale surface characterization and first-principles calculation. Results revealed that FLSP induced grain refinement and work-hardening, achieving 66.7 % decrease in wear rate. Such amelioration in wear resistance was tightly correlated to the combined evolution of tribo-induced recrystallization and tribo-oxidation. The potential mechanisms were detailed unraveled, via establishing the relationships between continuous dynamic recrystallization, inclusion dissociation, glazed layer cracking and debris discharge during wear at high temperature. Compared to untreated counterpart, FLSP-refined surface evolved into a thicker and more stable recrystallized layer composed of finer nano-grains during sliding, releasing inclusion with declined dimension into glazed layer under intergranular oxidation. Smaller inclusion leaved limited larger oxide grain domain around to alleviate the stress concentration due to plastic discrepancy, avoiding the catastrophic delamination caused by fatal cracking and inhibiting the matrix removal under sliding. The findings provided essential insights to well understand the high-temperature wear mechanisms of Ti-6Al-4 V alloy and guide their anti-wear designs.