A consistent micromechanical model of deformation of shape memory alloys for both forward and reverse thermoelastic phase transformations. It is assumed that the direct thermoelastic transformation reduced to the processes taking place at the same time the origin and development of martensitic elements, and, in this model, in contrast to known analogs, both components of the process are rigidly connected to each other in terms of the volume fraction of the martensite phase. Targeting emerging martensitic element is determined by acting in this microvolume stresses with regard to the internal microstrain. In the development of martensitic element does not change its orientation, and the increase of its volume is proportional to the current value of this amount. The process of reconversion is to reduce to zero volume of martensite elements. Derived from these assumptions defining relations allowed qualitatively correctly describe the accumulation of strain direct conversion taking into account the volume effect of the reaction, a phenomenon oriented transformation, monotonous and reversible shape memory.