铜箔抗拉强度及延伸率的尺寸效应研究

Research of size effects on tensile strength and elongation of copper foil

为了研究尺寸参数对金属箔材的抗拉强度和延伸率的影响规律,采用不同厚度和晶粒尺寸的铜箔进行室温单向拉伸试验.试验结果表明:铜箔的抗拉强度和延伸率同时受厚度和晶粒尺寸的影响,这种尺寸效应的描述必须引入无量纲的厚度晶粒尺寸比(T/D)作为比较参数.抗拉强度在不同厚度晶粒尺寸比区间内的变化规律不同;而延伸率在厚度晶粒尺寸比相同时都随厚度的减小而降低.拉伸断口的扫描电镜分析显示箔材的延伸率随着厚度的减小出现的突降和断裂机制的变化有关.

Tensile tests of copper foil with various thickness and grain sizes were performed at room temperature to investigate the size effects on tensile strength and elongation.The results show that the tensile strength and elongation are affected by the thickness and grain size together,and then the ratio of thickness to average grain diameter（T/D ratio） must be introduced to represent the size effects rightly.The relationships between the tensile strength and T/D ratio are different in distinct T/D ratio intervals.The elongation decreases with the decreasing thickness while the T/D ratio is constant.The tensile fracture surface was observed by SEM.The analyses indicate that the sharp decline of elongation with the decreasing thickness is attributed to the transformation of fracture mechanism.