Influence of copper on the deformation behavior of NiTi shape memory alloys in isothermal compression

Abstract

NiTi alloys are more commonly employed in engineering and medical applications because of its appealing shape memory and superelastic qualities. Recent efforts have been made to increase their thermal memory, mechanical capabilities, and corrosion resistance by alloying, heat treatment, and other means. NiTiCu alloys are the most often utilised ternary alloy in actuator applications. However, there is a scarcity of literature on the hot deformation properties or deformation process maps of NiTiCu shape memory alloys. To make cylindrical ingots, elemental forms of high purity nickel, titanium, and copper were melted in a vacuum induction melting furnace. These ingots were homogenised at 900 °C, quenched in water to room temperature, then machined to achieve a length-to-diameter ratio of 1.5, which is appropriate for doing hot deformation tests in a Gleeble thermo-mechanical simulator. The samples were exposed to strain rates of 0.01, 0.1, 1, and 10 s−1, respectively, and the data acquired was used to build a deformation processing map. The zones of instability were defined, and the dominating operational mechanisms in various regimes were projected and reported.