Microstructure and properties of high-conductivity, super-high-strength Cu-8.0Ni-1.8Si-0.6Sn-0.15Mg alloy

A high-conductivity and super-high-strength alloy, Cu-8.0Ni-1.8Si-0.6Sn-0.15Mg, has been developed. The processing conditions of the alloy have been investigated. The evolution of microstructure of the alloy on aging has been examined by transmission electron microscopy. The processing condition giving the highest hardness and good electrical conductivity is as follows: solution treatment at 970 degrees C for 4 h, cold rolling to 60% reduction, and aging at 500 degrees C for 30 min. The processed alloy has an average tensile strength of 1180 MPa, 0.2% proof strength of 795 MPa, elongation of 2.75%, and average electrical conductivity of 26.5% International Annealed Copper Standard (IACS). Orthorhombic Ni2Si precipitates are responsible for the age-hardening effect. The orientation relationship between the precipitates and the matrix is (110)(m)//(211)(p) and [001](m)/[01 (1) over bar](p). DO22 ordering together with spinodal decomposition also contributed to the hardening.