Effect of Burst-Type Martensitic Transformation on Superelastic and Elastocaloric Properties in a 〈116〉 Oriented Cu70.5Al17.5Mn12 Single Crystal

We report the occurrence of stress-induced burst-type martensitic transformation in a 〈116〉A oriented Cu70.5Al17.5Mn12 single crystal. The burst-type transformation is observed in the reverse transformation of unloading from 250 K to 370 K in tension, showing strong coupling with plastic deformation in the temperature range between 310 K and 370 K. Such coupling greatly exacerbates the stress hysteresis and energy dissipation in association with the stress-induced transformation, resulting in a significant enhancement in the mechanical damping and degradation in the elastocaloric response. In particular, the merit index for damping exhibits a remarkably high value of 0.903 at 370 K, demonstrating the huge potential of coupled burst-type transformation and plastic deformation in manipulating damping properties. Moreover, it is evidenced that the microstructural evolution of burst-type transformation greatly deviates from that of the thermoelastic transformation.