Effect of trace silicon addition on microstructure and properties of a Cu–0.26Cr–0.14Mg alloy

Abstract

In this study, Cu-0.26Cr-0.14Mg and Cu-0.26Cr-0.14Mg-0.02Si (wt.%, nominal composition) alloys were used to study the effect of adding a small amount of Si on the comprehensive properties, microstructure by thermo-mechanical treatment. The properties results showed that the Cu–0.26Cr–0.14Mg–0.02Si alloy had a higher strength and electrical conductivity than Cu–0.26Cr–0.14Mg alloy. After 80% cold rolling and aging at 500 °C for 20 min, the hardness, tensile strength, and electrical conductivity of Cu–0.26Cr–0.14Mg–0.02Si alloy reached 162.8 HV, 523 MPa, and 82.0 %IACS, respectively. The microstructure results showed that Cr particles existed in the form of G.P zones in the early stage of aging, and there were three forms of existence in the later stage of aging: coffee-beans, Moiré fringes, and rod-like precipitates. The addition of Si greatly promoted the precipitation of the alloying elements, increased the fraction of the precipitates, refined the size of the precipitates, and thus improved the Orowan-Ashby strengthening and dislocation strengthening effects.