Using a rational approach of thermodynamics formulated a complete system of defining relations, describing the thermomechanical behavior of shape memory alloys such as NiTi, undergo two-stage (rhombohedral and martensitic) phase transitions. Sufficient conditions for the fulfillment of the dissipative inequality for such processes. Obtained connected heat equation, which takes into account the absorption and release of latent heat for both phase transitions and dissipative phenomena. Under this system, it formulated and solved numerically simple one-dimensional problem of two connected deformed state, the phase composition and temperature distribution of such materials. It is shown that the effect of dissipation increases with the applied voltage.