Softening and compressive twinning in nanosecond ultraviolet pulsed laser-treated Ti6Al4V

Ti6Al4V was surface treated in ambient conditions with nanosecond pulse ultraviolet laser, using fluences of 539 and 123 MW/cm(2). Transmission electron microscopy of nanoblades revealed modified layers of 1.26 mu m and 750 nm respectively. Nanoindentation revealed softening of Ti6Al4V, which can be related to the formation of martensite in the region closest to the surface. Unusual compression {10 (1) over bar1} twins are formed in the region adjacent to the unmodified parent phase, which can be related to the nanosecond pulse-induced shock wave. The modified region exhibits characteristic features of heat treated and mechanically deformed Ti6Al4V, suggesting a thermomechanical effect of laser treatment. (C) 2015 Elsevier Ltd. All rights reserved.