Phase transformation temperatures and pseudoelasticity behavior of NiTi-Cu ternary shape memory alloys: A molecular dynamics simulation study

NiTi alloy is an attractive alloy particularly in biomedical, aerospace and heat pump applications due to its biocompatibility in addition to its unique properties such as excellent shape memory (SME) and its pseudoelasticity effects (PE). These properties come from the ability of this alloy to show phase transformation during heating/cooling and during loading/unloading. The phase transformation temperatures and pseudoelasticity behaviour strongly depend on the composition of the alloy. For instance, the replacement of Ni and Ti by the transition elements such as V, Cr, Mn, Fe, Co could lower the Martensite start (Ms) temperature while substitution of Hf, Zr, Ag and Au for Ni and substitution of Sc, Y, Hf, Zr for Ti could increase Ms temperature. Thus, it’s important to fully understand the third alloying elements’ effects on the properties of these alloys from atomic point of view. Molecular dynamic as an atomic-level simulation can be helpful to investigate the effect of different compositions including the addition of a third element on the properties of these alloys to improve their performance. To provide a real-time insight during phase transformations at the atomic scale, an MD simulation has been implemented for the Ni-Ti binary system doped with Copper (Cu) element with different Cu concentration. The cooling/reheating and loading/unloading processes will be applied to the system to simulate temperature-induced and stress-induced phase transformations respectively.