Tensile properties and transformation temperatures of Pd added Ti-Ni alloy dental castings.

The effect of palladium (Pd) addition to Ti-Ni alloy as the third element was investigated to improve the super-elasticity of the alloy castings at body temperature for dental application. Ti-50.8Ni (at %) alloy, which exhibited super-elasticity at 310 K in castings, was used for comparison. 5.0, 7.5, 10.0 and 15.0 at % Pd was added to Ti-50.0Ni alloy by the substitution for Ni. The change in the proportion of Ti and Ni was also examined at the fixed Pd addition of 7.5 at %. The properties of the alloys were investigated in tensile test and differential scanning calorimetry (DSC). Ti-42.5Ni-7.5Pd alloy castings showed good super-elasticity among the examined alloys from the viewpoint of residual strain and elongation. Moreover, apparent proof stress could be changeable by the proportion of Ti and Ni with residual strain being kept low. Ti-42.5Ni-7.5Pd alloy castings exhibited better super-elastic flexibility than Ti-50.8Ni alloy, which is proven by lower apparent proof stress and larger elongation. This flexibility appears to be caused by its relatively high martensitic transformation starting temperature point. It is suggested that this flexibility with super-elasticity could widen the clinical application of the alloy casting in dentistry.