Heat sink avalanche dynamics in elastocaloric Cu–Al–Ni single crystal detected by infrared calorimetry and Gaussian filtering

The physics behind the cooling process occurring in an elastocaloric Cu–Al–Ni wire during the martensite to austenite transition after stress release is studied. A previous experiment using infrared imaging determined the temperature map evolution of the sample surface and obtained the qualitative evolution of heat sinks by reversing the Fourier heat equation.

The results were only qualitative due to the data smoothing algorithm that was used to correct the experimental noise. We analyze the original data by using a more appropriate Gaussian filter to reject the noise without smoothing the sharp martensite-austenite interfaces. Results show a much better spatial resolution that enables us to obtain new physical variables characterizing the discontinuous, avalanche-like, cooling process: the sink width, the sink cooling power, and the sink velocity.