Influence of composition and purity on tensile properties of Ni-Ti alloy castings.

The influence of composition and purity of titanium on the mechanical properties and the transformation temperatures of Ni-Ti alloy dental castings was investigated by tensile testing and differential scanning calorimetry (DSC). The compositions of the ingots were 49.0-49.2 at% of titanium content. Three grades of titanium of relatively high purity were used as starting materials. The result showed Ni-49.0Ti to be a somewhat brittle property, and Ni-49.2Ti to have low apparent proof strength and large elongation. Residual strain increased with increasing titanium content. Even small reductions of titanium purity influenced the tensile properties and the transformation temperatures, causing high apparent proof strength, low residual strain and low elongation because of the reduction in transformation temperatures.