Properties and precipitates of the high strength and electrical conductivity Cu-Ni-Co-Si-Cr alloy

Abstract

• The (Ni, Co) 2 Si and Cr nano precipitates uniformly distributed in the alloy provide good strength and conductivity. • Excellent ductility is provided because the small lattice mismatch strain between the precipitates and the Cu matrix. • The introduction of deformation twins improves the strength and ductility of the alloy. In this paper, a novel Cu-1.5Ni-1.1Co-0.6Si-0.1Cr (wt.%) alloy with high strength and electrical conductivity was designed. After aging, excellent properties of 857±12 MPa yield strength, 300±8 HV microhardness, 42.8 ± 2.5% IACS conductivity, and 7 ± 0.5% elongation were obtained. According to the atomic structure, part of Ni atoms in Ni 2 Si can be replaced by Co atoms to form nano-precipitates (Ni, Co) 2 Si. The alloy's high strength and conductivity are mainly attributed to the fine and uniformly distributed (Ni, Co) 2 Si and Cr nano precipitates. The alloy strength was also enhanced by twins, dislocations, and grain refining strengthening. Based on the investigations of deformation microstructure and the orientation relationship between the (Ni, Co) 2 Si precipitates and the Cu matrix, the main reason for elongation increase is attributed to the formation of deformation twins and the small lattice mismatch strain at the coherent interfaces of precipitates and the Cu matrix.