Calculation of Poisson's ratios of TiNi shape memory crystals through their elastic constants.

Extreme and average Poisson's ratios of TiNi shape memory alloy crystals were calculated. The calculations were performed using formulas that determine the Poisson's ratio through the lattice elastic constants of alloys obtained either from the first principles or experimentally and taken from the literature. It was found that TiNi alloys can be considered as auxetics (materials with a negative Poisson's ratio µ<0). [ABSTRACT FROM AUTHOR]