Orientation dependent compression behavior of Co35Ni35Al30 single crystals

The shape memory effect (SME) and superelasticity (SE) behavior of homogenized Co35Ni35Al30 single crystals were systematically characterized along the [100], [110] and [111] orientations under compression. The shape memory behavior of CoNiAl was found to be highly orientation and stress/temperature dependent. Maximum compressive recoverable strains were 3.98% in [110], 3% in [100] and 0.30% in [111] orientations, respectively. The Co35Ni35Al30 demonstrated a very high superelastic temperature window of more than 350 °C along the [100] and [110] orientations. Moreover, two-way shape memory effect with very low thermal hysteresis of about 6 °C was observed along the [110] orientation. The large decrease of recoverable strain and hysteresis with stress (or temperature) was mainly attributed to the difference of elastic moduli of transforming phases.