Purpose here is to analyse the processes responsible for reversible change of shape in materials which are deformed mainly by phase-twinning mechanisms. The investigations were carried out on compositions 50Ti47,5Ni2,5Fe and 50Ti40Ni10Cu (at.%). The alloys were annealed in vacuo for 1 hr at 1073 K. The experiments were carried out in torsion. Conditions were such that the stress was never greater than the dislocation yield point. So the deformation developed either by phase transformation or twinning of the martensitic phase. X-ray structural analysis showed that compositions TiNiCu and TiNiFe are subject to martensitic transformations. These reports are important from the practical point of view, because they indicate the possibility of controlling the trajectories and motion of the working elements of the apparatus.