Abstract
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The thickness size effect of asymmetric rolled and annealed copper foils at room temperature was studied. To study the influence of grain size, thickness, thickness/grain size ratio, dislocation density on mechanical properties, parts of the rolled sheets with different thicknesses were annealed at 600 ��� as comparison. Through uniaxial tensile experiment at room temperature and electron microscope observation, the mechanical properties and microstructure of foils were analyzed respectively. The results show that the ultimate tensile strength of the material is related to the grain size, thickness, thickness/grain size ratio and dislocation density. For the rolled samples, the grain size, thickness and dislocation density work together, so that as the thickness of material decreases, its ultimate tensile strength shows "the smaller, the stronger firstly", and then shows "the smaller, the weaker". For the annealed samples, it is only affected by the number of grains in the thickness direction. As the thickness of material decreases, its ultimate tensile strength shows the size effect of "the smaller, the weaker". In terms of elongation, it gradually decrease as the thickness of material decreases for both the rolled state and the annealed state samples.