Computational modelling of Ti50Pt50-xMx shape memory alloys (M: Ni, Ir or Pd and x = 6.25-43.75 at.%)

Abstract

The ab initio density functional theory approach was employed to study the effect of Ni, Ir or Pd addition to the TiPt shape memory alloy. The supercell approach in VASP was used to substitute Pt with 6.25, 18.75, 25.00, 31.25 and 43.75 at.% Ni, Ir or Pd in the B2 TiPt structure. The mechanical stability from elastic properties and phonon dispersion calculations of these alloys were then evaluated. Results suggest that Ni addition reduced the transformation temperatures of the TiPt alloy as indicated by an increase in shear modulus C'. Ir addition increased the martensitic transformation temperature of TiPt, since it gave the lowest shear modulus values at both 18.75 and 25 at.% Ir. However, a high addition of Pd (x = 25) decreased the transformation temperature of the B2 to B19 TiPt.