Deformation behavior of shape memory alloys in various temperature ranges

Introducing the phase interaction energy between austenite and detwinned martensite, the present authors studied pseudoelastic transformations of shape memory alloys and have analytically shown that the transformation is a thermomechanical process along a stable equilibrium path, as observed in experiments. To further exploit the phase interaction energy, here we present a unified approach for treating both shape memory effect and pseudoelasticity, taking into account another state of phase, i.e., twinned martensite. Analytical models formulated using experimental data will be compared with experimental constitutive relationships. A good curve-fitting to complicated experimental stress-strain curves is also presented through a higher-order polynomial representation of the interaction energy function.