Surface roughness-controlled superelastic hysteresis in shape memory microwires

Superelasticity in Cu–Zn–Al shape memory alloy microwires is studied as a function of surface roughness. Wires with a rough surface finish dissipate more than twice as much energy per unit volume during a superelastic cycle than do electropolished wires with smooth surfaces. We attribute the increased damping in wires with large surface roughness to the increased density of surface obstacles where frictional energy is dissipated as heat during martensitic phase transformation.