| The production of biomedical devices from Nitinol requires precise control of the transformational and mechanical properties of the material. Heat treatments can be utilized to tailor the properties and optimize performance. The effect of heat treatments of 300 ∼ 550°C for-2 ∼180 minutes on Ti-50.8%Ni (at.%) wire of 30% and 50% cold work was investigated. Transformational and mechanical properties were characterized through the BFR method and tensile testing. Thermally activated precipitation and annealing processes occurred. Annealing processes reduced the curvature and increased the slope of BFR plots. The R-phase was present with greater frequency and prominence in the 50% cold-worked wire than the 30% cold-worked wire. Two TTT diagrams were constructed illustrating the trends in Af of the wires. A maximum precipitation rate occurred at approximately 450°C. The trends in UTS, UP, and LP are outlined for all heat treatment conditions. Recrystallization began at 450°C for both wires. |
