Differential effects of Zn and Co solutes on the properties of Cu–Ni–Sn alloys

Abstract

In order to solve the segregation and discontinuous precipitation of Cu–Ni–Sn alloys and explore the influence mechanism of solid soluble microelements on the microstructure and properties. Herein, based on the cluster-plus-glue-atom model, Zn or Co, with different solubilities in Cu, was selected as the fourth element in the way of replacing a small portion of Sn for the composition design of Cu–Ni–Sn–Zn (Co) series alloys. The solid solution forms and positions of Zn and Co solutes were revealed according to EPMA composition analysis and variation of the lattice parameter of the Cu matrix in solution treated alloys, and form atomic site occupation point of view, the influence of Zn or Co on solidus-liquidus temperature range were discussed. Furthermore, phase transformation and resistivity thermal stability with temperature rising were investigated and discussed utilizing results of variable temperature resistance. These results show that Zn solutes dissolve in the form of clusters, resulting in a strong solid solution strengthening, existing less effect on conductivity, and increasing comprehensive properties after long-term aging, which indicates that Zn can be a good candidate for the multi-component design of Cu–Ni–Sn alloys. These findings may offer new insights on composition optimization of Cu–Ni–Sn alloy.