Preparation Of Single Crystal Silver,Aluminumand And The Influence On The SFE Of Deformation Texture And Microstructure For Cold Drawing

Silver is an excellent conductor of electricity and heat, and has good signal transmission and thermal conductivity. As a conductor, aluminum has the charateristics such as cheap price also light weight and excellent conductivity. Both of them are widely used in the preparation of package leads. With the fast development of the semiconductor, integrated circuits and electronic component, the technology of package is more and more important. The materials of package are paid more attentions. However, a number of grain boundaries exit in the polycrystalline silver and aluminum, which will weaken the effect of transmitting signal. Therefore, single crystal silver and aluminum wires have a great advantage in signal transmitting by eliminating the grain boundary and the preparation of single crystal with high quality is paid widely attentions. The present paper focuses on the effect of solid liquid interface, drawing speed and temperature on the preparation of single crystal silver and aluminum. Meanwhile, because of the significant difference of the stacking fault energy (SFE) between silver and aluminum, SFE, as an intrinsic property, has a significant influence on the evolution of the deformation microstructure and texture. In practice, the metals wires must be cold drawn deformation to enhance their mechanical properties before the practical application in communication field. Therefore, it is very essential to investigate the effect of SFE on the evolution of cold drawn microstructure and texture. In the present paper, the evolution of microstructure and texture of cold drawn silver and aluminum was characterized by the electron back scatter diffraction (EBSD) and transmission electron microscope (TEM). Meanwhile, the relativity of deformation temperature on cold drawn aluminum with strong <100> original texture was also studied in this paper.The results show that the best preparation technological parameters of single crystals are shown as follows. For<111> single crystal silver, the distance between solid-liquid interface and insulation board is 2.7mm,1400℃ insulation, drawing rate 1 μm/s, and for<110> single crystal aluminum, the distance between solid-liquid interface and insulation board is 15.5 mm, 865℃ insulation, drawing rate 1 μm/s. The orientation of single crystal silver and aluminum were characterized by EBSD.The results of cold-drawn silver wires show that macro subdivision was obviously observed in cold-drawn silver, with fiber microstructure forming at high strains. With strains increasing, the grains are elongated along the direction of cold drawing, and the texture components of<111> and<100> have increased first and then decreased. As the strain up to 2.77, the stable texture component is<100>+<lll>. TEM analysis results show that discrete dislocation formed at low stains, at medium strains, high density dislocation walls and micro bands were observed in the microstructure. At the strain of 0.94, shear band appeared. As the strain up to 1.96, GNBs were parallel to the drawing direction. The results of cold drawn aluminum show that<100>+<111> are also the most stable texture component.SFEs have a significant influence on drawn texture of FCC metals.<100>+<111> are the most stable texture. However, lots of complex texture component also exists in silver at high strains. Meanwhile, deformation mechanisms in two metals are different. The predominant mechanism is dislocation slip in aluminum. However, for silver with low SFE, the predominant mechanism is dislocation slip at low strains and twinning is the predominant mechanism at high strains.The results of effect of deformation temperature on texture evolution of cold drawn aluminum with initial strong<100> original texture show that<100>+<111> double texture component formed at 80 ℃ and cryogenic temperature. However, the decrease in deformation temperature will enhance<111> orientation stability at high strains. The results of misorientation analysis show that a 5° peak forms at two deformation temperature, but the frequency of the 5° peak is difference. This illustrates that the decrease in deformation temperature will increase the dislocation density.