Effect of Silver Content on the Martensite Transformation Temperature in NiTiAg Shape Memory Alloys for Biomedical Applications

Since 2005, when the ternary NiTiAg shape memory alloy was first proposed, this promising biomaterial has not been properly studied in terms of alloy-melting and thermomechanical processing. The aim of this study is to evaluate the influence of silver content on the microstructure of this ternary alloy in as-cast, solution-treated and cold deformed states. The alloys, with silver content varying from 0.25 to 4% in weight, will be vacuum arc melted from high purity Ni, Ti and Ag, seeking a near-equiatomic Ni/Ti relationship. The solution-treatment will be done in an Argon atmosphere at 800°C for 1h, and the thermomechanical processing by rotary swaging. The martensitic transformation temperatures will be determined by DSC and the shape recovery will be analyzed by tensile test. The microstructure will be explored by optical and scanning electron microscopy.