Production of Ti-22Nb-6Zr Shape Memory Alloy by Powder Metallurgy 2012-36-0467

Shape Memory Alloys (SMA) are novel materials which have the ability to return to a predetermined shape when heated. SMA are useful as actuators which are materials that change shape, stiffness, position, natural frequency, and other mechanical characteristics in response to temperature or electromagnetic fields. Applications include engines in cars and airplanes, electrical generators and surgical implants that make use of the mechanical energy resulting from the shape transformations. Powder metallurgy allows the SMA production with savings of energy and time and with higher microstructural homogeneity than those obtained by conventional processes. In this work a new nickel-free titanium alloy Ti-22Nb-6Zr (%at) was produced in order to expand the application field of SMA. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering between 800-1600°C, in vacuum. Sintered samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively. Density was measured by Archimedes method. It was shown that the samples were sintered to high densities and presented homogeneous microstructure with complete dissolution of alloying elements in the titanium matrix.