Microstructure and Properties of Cu-Ni-Co-Si-Cr-Mg Alloy by Multistage Thermomechanical Treatment

A Cu-1.3Ni-1.2Co-0.7Si-0.3Cr-0.1Mg alloy with high strength and high conductivity was designed and prepared in this work. The effects of multistage thermomechanical treatment on the microstructure and properties of the alloy and its strengthening mechanism were studied. The results showed that a large number of nanoscale β-Ni 3 Si, δ-(Ni,Co) 2 Si and Cr phase particles precipitated in the high-density dislocation region and sub-grain boundaries during aging, and submicron Cr 3 Si phase particles formed during solidification of the alloy. The β-Ni 3 Si, δ-(Ni,Co) 2 Si phases had the following orientation relationship with the Cu matrix: [112] Cu //[112] β //[001] δ , (11-1) Cu //(11-1) β //(220) δ and (2-20) Cu //(1-10) β //(4-20) δ . The tensile strength, yield strength and electrical conductivity of the alloy were 882 MPa, 857 MPa and 46.7%IACS, respectively. The main strengthening mechanisms of the alloy were precipitation strengthening, strain strengthening and sub-structure strengthening through the strengthening model calculation and measured strength