On the material characteristics of Ni modified Cu32Zn10Sn shape memory alloys: Mechanical and damping behaviour in consideration

The results from preliminary investigations on the mechanical properties and damping behaviour of Cu-32Zn-10Sn-xNi alloys (where x = 0.2 and 0.4) for potential application as thermo-responsive shape memory material is presented. The Cu-Zn-Sn alloys were produced through conventional liquid metallurgy route, subjected to homogenization treatment at 600 °C, and characterized using scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), hardness testing, tensile testing, and damping analysis. The results indicate that microstructures of the alloys were characterized with globular shaped grains, with marginal difference in the grain sizes and grain morphology. The alloys had in common Cu₃Zn, Cu₆Sn₅, and CuSn intermetallic phases, while Ni₃Sn₂ intermetallic phase was the only distinct phase present in the Ni modified CuZnSn alloy that was absent in the unmodified CuZnSn alloy composition. In contrast to the hardness trend, the strength of the alloys was slightly invariant to the Ni addition (maximum of 3.77% improvement), and exhibited towering improvement in % elongation (44.2% and 86.5% for 0.2 wt% and 0.4 wt% Ni additions, respectively). The damping capacities of the 0.4 wt% Ni modified CuZnSn alloy (0.016 – 0.031) for the range of test temperatures, was significantly higher compared to the range recorded for the unmodified and 0.2 wt% Ni modified CuZnSn alloys (0.004–0.017 for both). The study showed that micro-alloying CuZnSn alloy with maximum of 0.4 wt% Ni, resulted in the best balance of mechanical and damping properties.