Martensite structure and phase transformation of quaternary ZrCuAlCo high temperature shape memory alloys

The effects of Al and Co co-doping on the microstructure and martensitic transformation of ZrCu alloys were investigated. It was found that the martensitic transformation temperatures and the temperature hysteresis decrease obviously in quaternary ZrCuAlCo alloys compared with that in equiatomic ZrCu binary alloy. Except for the usually observed (0 2 1) type I and (0 0 1) compound twins, a small amount of (111¯) type I and (201¯) compound twins were also observed as accommodation twins in the present study to reduce the shape change during the phase transformation. In addition, anti-phase boundary (APB) like structure was observed in the present alloys.