Manufacturing and characterization of dental shape memory alloy

A powder mixture of 55 wt% Ni and 45 wt% Ti was prepared by mixing in a ball mill. The samples were then compacted at 300, 400, 500 and 700 MPa, and sintered at 950 °C for 9 h under controlled atmosphere (argon) to decrease the oxidation process. The same thing was made for the samples with V and Cr additives. The samples after being sintered were found to consist of two phases (martensite and austenite) at room temperature. It was found that increasing of the compacting pressure (for all samples) increases the hardness, decreases the porosity but has little effect on the transformation temperatures. The sample with 0.3 wt% Cr compacted at 700 MPa had nearly the same properties (porosity, transformation temperatures and hardness) comparing to reference thermal archwires.