Low-frequency elastic and thermomechanical analysis of Ni-Mn-In(Co) single crystals

Martensitic transformation (MT) in Ni 45.0 Mn 36.7 In 13.3 Co 5.0 single crystals (SC) has been characterized by DSC and X-ray diffraction. Their elastic and thermomechanical properties have been investigated by a low-frequency dynamic-mechanical analysis in a tensile mode and by static mechanical compression made at different temperatures. The Young's modulus of the order of 10 GPa was measured in tensile tests along <100> crystallographic axis of austenite showing soft behavior in a broad temperature range whereby revealing a lattice instability similar to the classical Ni-Mn-Ga alloys. The compression tests along <100>, <011> and <111> directions have shown that despite a high brittleness the samples exhibit large martensitic plasticity, rubber-like behavior and superelasticity.