Effect of Sn and Zr addition on the martensitic transformation behavior of Ti-Mo shape memory alloys

The effect of Sn and Zr addition on the martensitic transformation temperature and lattice deformation strain of Ti-3 mol % Mo alloys was systematically investigated by differential scanning calorimetry and X-ray diffractometry. The addition of Sn and Zr to the Ti-3 mol % Mo alloy stabilized the parent β phase and decreased the temperature of the reverse martensitic transformation by 149 K/mol % Sn and 38 K/mol % Zr, respectively. Changes in the lattice deformation strains due to the Sn and Zr addition were evaluated from the lattice parameters of the β and α″ phases. Compared with β stabilizing elements, such as Nb, Mo, and Ta, Sn and Zr decrease the martensitic transformation temperatures without decreasing the lattice deformation strains.