Thermodynamics of stress-induced ferroelastic transitions: Influence of anisotropy and disorder

Abstract

Stress-induced stress-strain constitutive behavior has been studied in detail in ferroelastic martensites. It has been found that the weights of the long-range anisotropic interactions and of the disorder are important to determine the fine structure of the stress-strain curves. As experiments show, a wide variety of behaviors has been observed. A decrease of anisotropy and/or increase in the disorder results in changes in the temperature range where pseudoplastic and superelastic regimes are observed. Also, a smoothing of the stress-induced ferroelastic transition, accompanied with a decrease in the transition stress and the hysteresis area, is found. However, Clausius-Clapeyron slope has been observed not to depend on the specific values of anisotropy and disorder. This is in general agreement with experimental results in different alloy families, although some particular features differ from those in experiments. Elastocaloric effect has been studied as well. Varying the anisotropy slightly modifies the shape of the entropy change-temperature curve but the magnitude of the entropy change remains essentially constant.