Shape memory effects in porous Ti – 45.0 at.% Ni alloy produced by self-propagating high-temperature synthesis

Abstract

One way and two-way shape memory effects were studied on heating and cooling of preliminarily deformed porous Ti – 45.0 at.% Ni alloy produced by self-propagating high-temperature synthesis. The porous samples were initially deformed to different strains at a temperature of 25 °C and then they were subjected to heating and cooling through the temperature range of the martensitic transformations. The maximum given strain during preliminary deformation was 16% because further deformation of the sample resulted in porous sample failure. The results obtained have shown that the functional behavior of porous TiNi alloys differs from the properties of cast TiNi alloy. A strain recovery on heating due to the realization of the one-way shape memory effect, and a strain accumulation on cooling caused by a two-way shape memory effect, were observed if the preliminary strain was equal to 10% or higher. The dependencies of the values of one-way and two-way shape memory effects on preliminarily strain were non-linear; the strain increased significantly when the given strain rose from 7 to 14%, and hardly changed if the given strain was larger than 14%.