Effects of silicon and thermo-mechanical process on microstructure and properties of Cu-10Ni-3Al-0.8Si alloy

10Ni-3Al-0.8Si alloy with ultra-high strength was designed and its microstructure was studied using optical microscopy, scanning electron microscopy, transmission electron microscopy. The alloy went through a set of thermo-mechanical process: solution treated at 950 degrees C for 4 h, then cold-rolled by 50% and aged at 450 degrees C for 8 h, followed by 60% cold-rolling and aging at 450 degrees C for 8 h. After these treatment, the tensile strength was 1180 MPa, yield strength was 1133 MPa and electrical conductivity was 18.1% IACS, respectively. The comprehensive properties, especially the electrical conductivity of the designed alloy, were much higher than those of traditional Cu-Ni-Al alloys. The addition of silicon in the designed alloy hindered the precipitation of large-scale NiAl phase and improved the strength of the alloy. The orientation relationships between delta-Ni2Si, Ni3Al precipitates and copper matrix were: [001](Cu)parallel to[001](Ni3Al)parallel to[001](delta), (110)(Cu)parallel to(110)(Ni3Al)parallel to(010)delta, (1 (1) over bar 0)(Cu)parallel to(1 (1) over bar 0)(Ni3Al)parallel to(100)delta, respectively. (C) 2014 Published by Elsevier Ltd.