Research On The Strengthening Process Of Cu-Mg-Te Alloys With High Strength And High Conductivity

Copper alloys with high strength and high conductivity, as a kind of functional materials with excellent physical properties and mechanical properties, could be used to be the material of preparing the lead frame of integrated circuit(IC), the contact wire of electrified railway, the electrode of resistance welding and so on. In recent years, the continuous progress in the field of electronic information of microelectronics, computers, communications, industrial automation and control not only puts forward higher requirements of copper and copper alloys but also promotes the development of copper and copper alloy industry.The process of adding micro-alloying elements, the introduction of electromagnetic fields in the continuous casting process, as well as the rolling deformation of alloy ingots and subsequent heat treatment can improve and enhance the properties of copper alloys. In this paper, Cu-Mg-Te alloy was chosen, through adding micro-alloying elements of Y and B, the introduction of electromagnetic fields in the continuous casting process, as well as the rolling deformation of alloy ingots and subsequent heat treatment, the changes in the organizational structure and mechanical properties were investigated to get the best strengthening composition and enhance the comprehensive mechanical properties of Cu-Mg-Te alloy.The addition of Y and B could the grains of Cu-Mg-Te alloy. The tensile strength and elongation could be improved by the addition of rare earth of Y. However, when the content of Y was higher than0.04%, the conductivity of Cu-Mg-Te alloy decreased. And by making a comparison, the best content of Y was0.04%, the Cu-Mg-Te alloy could attain better comprehensive mechanical properties. When the Y of0.10%and B of0.03%were added in the Cu-Mg-Te alloy, the tensile strength and elongation of Cu-0.6Mg-0.15Te-0.1Y-0.03B alloy could reach up to247Mpa and41.8%, respectively, which increased21.7%and2.2%compared to the cast state. In addition, when the addition of Y and B was0.10%and0.01%, respectively, the Cu-0.6Mg-0.15Te-0.1Y-0.01B alloy could achieve the maximum conductivity of59.6%, which increased4.2%than that of cast state.The introduction of the electromagnetic field in the continuous casting process could refine the casting microstructure of Cu-Mg-Te alloy and improve the surface quality of the ingot, and made magnesium element uniformly distribute in the matrix. As well, the second phase particle of Cu2Te was much smaller and distributed more uniformly, and the content of oxide decreased. The mechanical properties of electromagnetic continuous casting copper alloys were much better than that of ordinary continuous casting Cu-Mg-Te alloy. Furthermore, compared with the ordinary continuous casting Cu-Mg-Te alloy without magnetic field, the tensile strength increased by26.3%, reaching240MPa, and the elongation reached45%, increased by21.6%.When The hot-rolled deformed deformation of Cu-0.51Mg-0.13Te-0.08Y alloy reached up to70%at850℃, its tensile strength and elongation increased from original220MPa and33.7%to final283.1MPa and49.43%, respectively. After the hot-rolled and cold-rolled process, the tensile strength had a substantial increase from220MPa to520MPa which indicated that the effect of work hardening was very obvious. The electrical conductivity of Cu-0.51Mg-0.13Te-0.08Y alloy undergone the rolling process had a slight decline. After hot rolling process, Cu-0.51Mg-0.13Te-0.08Y alloy carried out the annealing treatment in the temperature range from360℃to390℃could obtain more satisfactory mechanical properties, the tensile strength and elongation were more than485MPa andf13%, respectively.Cu-0.49Mg-0.17Te-0.14Y alloy undergone the hot-rolling deformation of50%and cold-rolling deformation of70%at850, the Vickers hardness is gradually decreased with the increasing annealing time, and the hardness of the alloy had a considerable decrease with the increasing annealing temperature, while the tensile strength of the alloy was reduced, but the elongation increased. At the stage of return annealing, the conductivity of the alloy had a significant recovery, but the increasing annealing time, the conductivity was decreased due to the emergence of new grains and the increase of grain boundaries. According to the comprehensive comparison, the cold-rolled state Cu-Mg-Te-Y alloy could get the best performance at the annealing temperature of390℃for1h.