SiC／Al合金层状复合材料的机械性能及损伤行为

Mechanical Properties and Damage Behaviors of SiC/Al Alloy Multilayered Composite Materials

在室温条件下测定了Ａｌ合金以连续层状形式存在于ＳｉＣ陶瓷层间并渗透入ＳｉＣ陶瓷层内、Ａｌ合金浓度呈层状变化高低相间，以及Ａｌ合金和ＳｉＣ陶瓷均匀分布相互渗透三种ＳｉＣ含量相同而结构形式不同的ＳｉＣ／Ａｌ合金复合材料的机械性能；用ＳＥＭ和光学显微镜观察分析了复合材料的断口形貌及裂纹扩展过程。结果表明，在ＳｉＣ陶瓷层间以连续层状形式存在的Ａｌ合金在应力作用下发生较大程度的塑性变形，在裂纹尾部被拉伸和形成桥接，引起能量耗散，减缓裂纹扩展速度，防止裂纹张开，使复合材料的韧性得到明显改善；ＳｉＣ／Ａｌ合金陶瓷─金属层状复合材料的损伤形式主要是ＳｉＣ陶瓷层开裂、金属层桥接和裂纹偏转。

The mechanical properties of three kinds of SiC/Al alloy composites which have the same SiC content but different structures are determined at room temperature. SEM fractography and optical microscopy analysis on crack propagation are performed.It's found that the SiC/Al alloy composites with continuous Al alloy layers between any two SiC layers possess the highest fracture toughness values due to plastic deformation of the ductile metal phase causing explicit energy dissipation, and stretching and bridging of the metal phase resulting in the diminution of crack propagation rate and the inhibition of crack opening.The main damage mechanisms of SiC/Al alloy ceramic-metal multilayered composites are identified to be cracks of the SiC ceramic layers, bridging of the ductile metal layers and crack deflection