硼-铝复合材料断裂过程的SEM研究
Tensile Fracture Processes in B/Al Composites Studied by SEM
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摘要: 本研究用真空热压法制备了两种不同纤维体积分数的单向硼纤维增强铝(B/Al)复合材料,进行了动态拉伸试验。通过在备有拉伸台的扫描电镜(SEM)下缓慢加载,连续观察了各种偏轴角纤维外露试样的断裂过程。并测定了纤维外露试样及完整试样的强度及其载荷-位移曲线。结果表明:复合材料纵向,即纤维方向与拉伸轴的夹角(偏轴角)对断裂机制有极大影响,试样的破坏符合一定规律;复合材料强度与偏轴角的关系同最大应变能理论所揭示的规律相一致。由此提出了B/Al复合材料在小角拉伸时的正断模型和在大角拉伸时的剪断模型,阐明了B/Al复合材料裂纹萌生,扩展及连接的微观断裂过程。研究还表明,两种模型过渡的特征转折角与最优偏轴角之间可能存在某种相对应的关系。Abstract: The fracture mechanism of composite metallic materials and the strengthening function of fibres are the important subjects worth studing.Recently, much attention has been paid to the fracture processes of metallic matrix composites. However,due to the lack of observations made directly during the deformation and f racture processes, it has been difficult to know exactly The mechanism of initiation and propagation of microcracks.The purpose of this paper is to investigate the fracture processes in Boron fibre reinforced Aluminium (B/Al) composites by using the in-situ technique in a scanning electrow microscope (SEM) and on the basis of observations mentioned above to analyze the mechanism of microcrack initiation and propagation in these composites.
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