The material characterization and mechanical behaviors of aluminum alloy (6063) were investigated using flat specimens and the butterfly specimens with a modified Arcan fixture. The butterfly specimens were tensile-loaded at various stress triaxiality by changing the loading angles of the Arcan fixture. The flat specimens were tensile-loaded at various strain rates. The results of tensile tests at various stress triaxiality showed that the curves of engineering stress-engineering strain are obviously different. The results of different strain rates tensile tests showed that the yield stress and fracture stress increased slightly with strain rates increasing, however the fracture strain decreased obviously with strain rates increasing, and the ultimate strength almost remained constant. The Johnson-cook constitutive model could be used to describe the dynamic axial crashing behavior of thin-walled 6063 aluminum alloy tubes under impact loading. The material constants of the Johnson-cook constitutive model and failure model were acquired to be used for FEM simulation through material characterization.
In this article a method of high speed scanning in Electron Beam Selective Melting (EBSM) technology is presented. Based on the conventional point-to-point vector scanning method, a scanning method nominated profile vector scanning was developed in cooperation with the existing manufacturing system. A scanning speed up to 200m/s was realized using the improved system. 3D parts from 316L metal powder were fabricated using this scanning system and the quality of the fabricated parts was evaluated.
The effects of inoculation on the damping property of Mg-8Zn-4Al-0.3Mn alloys have
been investigated. The results show that the damping property of ZA84 alloys reduces at room temperature after the addition of RE, whereas the damping property at high temperature increases obviously. The damping property of ZA84 alloys at room temperature and high temperature improves respectively after the addition of Al5TiB. It has reached Q-1=0.01 at room temperature with 0.25% Al5TiB. There exists a damping peak in all alloys at high temperature because of the viscous sliding of the grain boundaries and the inteneration of φ (Al2Mg5Zn2) phase at high temperature. It was found that the addition of RE could delay the temperature of damping peak occurs. The main damping mechanisms of ZA84 magnesium alloys with RE and Al5TiB additions are the dislocation damping and interface damping. The higher the movable dislocation density is, the finer the grains are and the more the grain boundaries and phase interfaces are, the better damping property of ZA84 alloys is.
The nano-scale indium tin oxide (ITO) particles are synthezed by liquid phase co-precipitation method under given conditions with solution of indium chloride, tin chloride and ammonia. The absolute ethyl alcohol or deionized water was used as solvent and the dodecylamine or hexadecylamine surfactant as a dispersant in the reaction system. The sample powder was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution electron microscopy (HRTEM). Based on the transmission electron micrograph, the influences of the two different solvents and the two different dispersants on the nanoparticle size and dispersion were studied respectively. The results shown that the ITO particles are finely crystallized body centered cubic structure. The particle size has distributed in 30nm to 90nm.
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