Grain ejection associated with thermocycling of Cu-Al-Ni shape memory alloy

The phenomenon of metallic grain ejection is for the first time explained. An evaluation of ejected grains was performed in Cu-Al-Ni shape memory alloy load-free cycled up to 500 times within the temperature interval of reversible martensitic transformation (RMT). An intergranular fracture mechanism related to RMT is proposed to this phenomenon. By image processing, 8 grains/cm2 after 500 cycles were measured. This is attributed to γ′1 martensite transformation at the grain boundaries.