Transformation of Co-Ni-Al single crystals in tension

We present for the first time pseudoelasticity and shape memory results on Co-Ni-Al single crystals in tension. The experimental transformation strains approached 6% in tension in the [1 1 5] orientation. Despite the considerable volume change (0.0447), the transformation exhibits remarkable pseudoelasticity and shape memory recoverability in tension. A theoretical treatment is presented to explain the tension compression asymmetry in the stress-strain response, the change in transformation hysteresis with stress, and the role of secondary phase on the transformation temperatures.