The effect of cobalt additives on martensitic transformations and deformation in sintered porous nickel titanium alloys

Porous nickel titanium (TiNi) shape memory alloys with cobalt additives have been obtained by reaction and diffusion sintering. Analysis of the experimental temperature dependence of the electric resistance and multiple shape memory effect leads to a conclusion that Co additives below 1 at% in reaction-sintered, and even more so in diffusion-sintered, alloys lead to a reduction in intrinsic internal stresses in the TiNi phase. Additives above 1 at% induce dispersion hardening of the alloy. At all concentrations, cobalt additives lead to obstacles for the martensitic phase transformations.