Size effects in the martensitic transformation hysteresis in Ni–Mn–Sn Heusler alloy films

Understanding the effect of small characteristic length scales on phase transformations requires microscopic observations to identify mechanisms which may influence the progression of the transformation. Here, we report thickness-dependent hysteresis in electrochemically deposited Ni–Mn–Sn Heusler alloy films, as observed by optical microscopy. This approach allows for analyzing size dependent phase transformation behavior within individual grains from films with decreasing thickness. Hysteresis is not correlated with grain size, but increases with decreasing film thickness following a power law relationship. This behavior is attributable to internal friction-induced energy dissipation at the film/substrate interface in microscale alloy films.