Kinetics of Thermoelastic Martensitic Transformation in TiNi

The kinetics of the thermoelastic martensitic transformations of types В2 ↔ В19′ and В2 ↔ R ↔ В19′ in cast and powder Ni55–Ti45 alloys is studied. A way of calculating temperature dependence n(T) of the relative amount of transformed phase from measurements of the martensitic peak of internal friction is proposed. Experimental dependences n(T) at various amplitudes of deformation and heating rates are obtained. Based on the thermodynamics of equilibrium processes, a theoretical model of thermoelastic transformation is developed and a formula for calculating dependence n(T) is obtained. Theoretical dependence n(T) agrees with the experimental data.