Effects of Si addition on properties and microstructure of CuCrZr alloy

Abstract

In order to develop high-strength and high-conductivity copper alloys with better comprehensive properties, the effects of Si addition on the mechanical properties, electrical conductivity and microstructure of CuCrZr alloy were investigated in this paper. The addition of Si element can improve the hardness, strength and ductility of CuCrZr alloy. The optimal peak aging parameter for CuCrZrSi alloy is 430 °C for 3 h, the hardness 228.92 HV, the tensile strength 646.76 MPa, and the elongation after fracture 10.67%. Compared with the CuCrZr alloy under the same process, the mechanical properties are increased by 10.3%, 11.9% and 16.9%, respectively. The conductivity is 4 ± 1%IACS lower than that of the sample without Si addition. The addition of Si element refines the deformation substructure and produces more Σ3n (n = 1, 2, 3) grain boundaries, thus providing more nucleation sites and higher driving forces for the precipitation phases. In both CuCrZr and CuCrZrSi alloys, the fine precipitation phases (<10 nm) fcc-Cr phase and orthorhombic-Cu8Zr3 phase, together with coarse precipitation phases (>100 nm) bcc-Cr phase and hcp-Zr phase can be observed. The orientation relationship among the two fine precipitation phases and the matrix is (1¯1¯1)[11¯0]Cu∥(1¯1¯1)[11¯0]Cr∥(133)[01¯1]Cu8Zr3. The Si element tends to precipitate together with the Cr phase and Zr phase, and acts to refine and spheroidize the precipitation phases.