Hysteresis and Anomaly in the Elastic Properties of the Shape Memory Alloy Ni0.507Ti0.493

Abstract

We report a clear demonstration of thermal hysteresis and elastic anomaly in the elastic constant, C T , of a shape memory alloy Ni 0:507 Ti 0:493 . The observed hysteresis and anomaly closely match the experimental data from the structural phase transition, the resistivity and the thermoelectric power measurements previously reported. The elastic anomaly was explained using a theory based on the band Jahn-Teller mechanism. The theory allows to predict the detailed nature of the structural transitions and also the symmetry of the Fermi levels.