P/6061Al的变形断裂特征和塑性

为了更清楚地认识颗粒增强铝塑性差的细微观机制, 进行了(Al₂O₃)_P/6061Al的拉伸和三点弯曲变形实验,并用扫描电镜观察了变形与断裂的细微观特征。发现: (1) 在加载过程中,总是基体先发生变形局部化,形成变形带; 变形带内较大的Al₂O₃颗粒优先开裂,形成颗粒尺度的微裂纹; 变形带内的集中变形和Al₂O₃颗粒的继续开裂交互作用,导致微裂纹沿着变形带连接与扩展进而发生宏观低塑性断裂;(2) 加载方式、材料状态和变形温度对上述过程没有本质影响。根据以上观察结果和颗粒增强铝的强化机理,讨论了塑性差的细微观机制以及材料状态和变形温度对(Al₂O₃)_P/6061Al塑性的影响。

DEFORMATION BEHAVIOR AND DUCTILITY OF P/6061Al(Solid Mechanics Research Institute, Beijing University of Aeronautics and Astronautics, Beijing 100083,China)

To better understand the mechanisms of poor ductility of particulate reinforced Al matrix composites, tensile deformation at room and liquid nitrogen temperature and notched specimen bending at room temperature were conducted for (Al 2O 3) P/6061Al. Deformation and fracture process of the composite was characterized by the following successive events: localized deformation of the matrix, cracking of larger reinforcement particles within the deformation bands, and failure along the localized deformation bands through interaction of further localized straining and promoted cracking. No essential effect of deformation mode, deformation temperature and material condition on the above characteristics was identified. Taking into account the limited beneficial effects of cryogenic temperature and cryogenic treatment on ductility, factors influencing and the potential of improving ductility of particulate reinforced Al matrix composites were discussed.