Nano-scale superelastic response of laser-welded NiTi shape-memory alloys

ABSTRACT In this work, Ni-Ti shape-memory alloy (SMA) plates were laser welded using different laser powers. A systematic trend of decreasing deterioration in nanomechanical properties – including superelastic recovery – from the weld centre, through the interface region and the heat-affected zone to the base–metal regimes has been observed. The extent of the deterioration increases with increasing laser power. The observations are explained in terms of a decreasing cooling rate and increasing austenite finish temperature (Af ) with an increase in laser power.