Deformation evolution of superelastic NiTi shape memory alloy microtube under quasistatic combined tension and torsion: I. displacement-proportional loading

Shape memory alloy is a thermomechanical coupling phase transformation material of multi-scale effect. Its deformation is path-dependent and may involve macroscopic instability. This paper reports the experimental results of deformation evolution of superelastic NiTi shape memory alloy mictotube subjected to displacement-proportional combined tension and torsion. We completed a series of tests focusing on both the stress-strain response and surface morphology of the microtube specimen. The experimental result comprehensively illustrates the deformation behavior of the material. This research is important for the study of the constitutive relation of this kind of material.