The mechanism of thermally driven shape recovery from a single variant of 2H-martensite to the parent austenitic phase is experimentally studied on a specimen of Cu–Al–Ni shape memory alloy (SMA). The formation and motion of the martensite-to-austenite transient interfaces is controlled by a thermal gradient, and recorded by a CCD camera. Independently, the moving boundaries are observed by an infrared camera to capture the temperature evolution accompanying the propagation. Both the velocity profiles of the propagation and the thermal images indicate that the shape recovery of SMAs is a complex dynamic mechanism, which cannot be described by a classical Stefan’s model of phase transitions, known from the thermal conductivity problem.
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