原位观察铜网格增强Al/Cu复合材料的断裂行为

将一种按正交法编织的铜网格作为增强体引入到铝基体中制备了Al/Cu复合材料,再借助原位拉伸扫描电镜(SEM),观察了铝铜复合材料的组织演变,研究了其断裂机理与力学性能之间的关系.结果表明:在相同轧制变形量下,25 ℃冷轧和400 ℃热轧均可破碎增强体铜网格,并使其均匀分布于基体铝板.复合板原位拉伸下的载荷-位移曲线均表现出明显的弹性阶段、塑性阶段和失效阶段,微裂纹在Cu颗粒周围和应力集中处萌生,主裂纹及其扩展主要是Cu颗粒周围界面分层开裂与微裂纹沿滑移线方向的扩展共同作用下形成的,并且最终沿滑移线的断裂路径与单轴拉伸方向呈45°.发生在Al层的塑性断裂和Al/Cu结合界面上的界面分层断裂是Al/Cu复合板两种主要的失效方式.

In-situ observation of fracture behavior of Cu mesh reinforced Al/Cu composite

A kind of copper mesh woven by orthogonal method was introduced into aluminum matrix as reinforcement phase to prepare Al/Cu composite. The microstructure evolution, the relationship between fracture mechanism and mechanical properties of the Al/Cu composite were both observed and investigated on line by means of in-situ tensile scanning electron microscope (SEM). It is found in this study that under the same rolling deformation, both 25 ℃ cold rolling and 400 ℃ hot rolling may break the reinforced copper mesh and make it uniformly distributed in the matrix aluminum plate. Recorded load-displacement curves of the composite plate under in-situ tension exhibit obvious elastic stage, plastic stage and failure stage. Microcracks initiate around the Cu particles or stress concentrations. The main crack and its propagation are mainly formed by joint action of delamination cracking of the interface around the Cu particles and propagation of the microcracks along the slip line. Finally, the fracture path along the slip line takes 45 °with the uniaxial tensile direction. The plastic fracture of Al layer and the delamination-induced fracture on the Al/Cu bonding interface are the two main failure modes of the Al/Cu composite plate.