Effects Of Alloying Element And Rolling Technology On The Microstructure And Properties Of High-Strength And High-Conductivity Cu-Mg-Te Alloys

As a kind of functional materials with excellent comprehensive physical properties and mechanical properties, high-strength and high-conductivity copper alloy is the material of IC lead frame and high-speed locomotive contact lines. Compared with other strengthening elements, the density of Mg and Te is very light, that could help to reduce specific gravity of copper alloy. We can obtain strengthened and high conductivity copper alloy with low cost by adding small amount of Mg and Te. The development of Cu-Mg-Te alloy has drawn wide attention.The effects of Mg and Te on the cast microstructure, mechanical properties and electric conductivity of high strength and good conductivity copper alloy were studied by using component analysis, optical microscope, electron probe, XRD, tensile test, scanning electron microscope and electrical conductivity test et. The results show that Te has very little influential to the mechanical property of copper alloy, because Cu2Te particle compounded by addition of Te is soft phase, which has little resistance for dislocation gliding. Mg can remarkably improve the mechanical property of as-cast copper alloy, the average of tensile strength is greater than 200MPa, and the average of elongation is greater than 30%. While the content of Mg is higher (0.556%), although the tensile strength reaches 213.9MPa, the electric conductivity reduces to 56.00% IACS. The mechanism of action is considered as solution strengthening of Mg, but electric conductivity reduces with the increasing of solid solubility. So it is better to control the content of Mg with a low value. Then we added Y to Cu-Mg-Te alloys. The effects of Y on the cast microstructure, mechanical properties and electric conductivity of Cu-Mg-Te alloys were studied. The results show that Y can improve slightly electrical conductivity in proportion to its content, when the content of Y is less than 0.050%. While the content of Y reached 0.052%, the tensile strength raises 15MPa, the elongation get remarkable improvement, but the electrical conductivity decreases a lot.The as-cast copper alloy with composition of MgO.509%, Te0.166%, Y0.032% were processed by hot rolling, cold rolling and heat-treatment of solution and ageing, which are aimed at improve combination property of Cu-Mg-Te alloy. The research shows that hot rolling can remarkably improve the tensile strength. The strengthening mechanism is considered as deformation strengthening and fine grain strengthening caused by hot rolling, work hardening caused by cold rolling, and grain refinement caused by recovery and recrystallization during ageing process. The strengthening effect of hot rolled & cold rolled bonding process is the best, and the tensile strength reaches the highest of 457MPa. The elongation is improved greatly through ageing treatment after hot rolled & cold rolled bonding process, which reaches up to 70%. But the tensile strength decreases. Basically, the electrical conductivity of rolled copper alloys is about 60%, which decreases a little compared to as-cast copper alloys.