Hysteretic Behaviour of Ferroelasticity of NiTi in Shear

In the present work, the hysteretic behavior of ferroelastic deformation via martensite variant reorientation in a Ti-50.15at.%Ni alloy is studied with cycling in shear. The stress hysteresis and the irreversible work dissipated during a cycle are found to decrease with cycling. The stress hysteresis is found to be dependent on the strain span of the loop but to be independent of the apparent strain about which the loop is performed. The mechanical hysteresis is attributed to two contributions: frictional resistance to twin boundary movement and matrix resistance to shape change of polycrystalline matrices.