Properties And Drawn Deformation Mechanism Of The Single Crystal Copper With Different Initial Orientation

In the present paper, a seed crystal method which is the improvement of Bridgman method had been used to produce single crystal coppers with initial orientation of<100>,<110> and <111> parallel to axis wire. The mechanical and resisitance properties of drawn single crystal copper with different orientations have been measured, and the evolution of microstructure of cold-drawing single crystal copper has been analyzed using TEM and EBSD. The density of dislocation of drawn copper has been calculated from the datum of DSC. Based on the evolution of microstructure, the property of drawn single crystal copper copper has been explained qualitatively. In order to compare with drawn single crystal copper wires, properties and microstructure of drawn polycrystalline copper by the continuous casting were analyzed.The results of the study show that the tensile strengthen of drawn single crystal copper would increase when the strain increasing. The tensile strengthen of<111> single crystal is the largest one of the three orientation single crystals,<100> single crystal is lowest, and<110> single crystal in the between. At low strain, the tensile strengthen of<100> close to<110>, and significantly lower than that of<111>. At the high strain, the tensile strengthen of<110> is close to that of<111>, and much higher than that of<100>. However, compared to tensile strengthening, the evolution of reduction of area of drawn single crystal varies in a contrary way with strain increasing.The resistivity evolution of single crystals with three orientations includes three stages with strain increasing. When the strain is less than 1.65, resistivity increases with the strain increasing. At the strains between 1.65 and 2.25, the resistivity decreases with the strain increasing. When the strains are increased to more than 2.22, the results of microstructure of drawn copper wires show that there is a critical strain of the formation of high angle boundaries (HABs) during cold drawing process. When the strain is lower than the critical strain, the HABs mainly corresponded to interface between different fiber texture components parallel to axis direction of wire, but when the strain is higher than the critical, the HABs also appears within one fiber texture component. The initial orientation affeets the evolution of microstructure and macro-texture resulting in the change of the property of drawn coppers. The analysis of the strengthen for drawn copper based on the parameters of microstructure shows that there is a good agreement between the calculated results by dislocation strengthening model and the experimental datum for polycrystalline copper and cold drawn<100>,<110>,but for<111> single crystal copper, there is a much deviation in the high strain.