高强度高韧性铝合金基复合材料的制备和断裂机制

FABRICATION AND FRACTURE MECHANISM OF LD2 Al ALLOY MATRIX COMPOSITE WITH HIGH STRENGTH AND TOUGHNESS

为解决金属基复合材料低韧性的缺点，采用宏观结构设计方法制备了断裂韧性达到相应铝合金水平的 ＳｉＣｐ－ＬＤ２／ＬＤ２复合材料、与同体积分数的普通 ＳｉＣｐ／ＬＤ２复合材料比较，其强化效果得以保持，并提高了材料的断裂功，断裂过程表现出阶段性，避免了普通复合材料灾难性失效突然发生的缺点．高体积分数的 ＳｉＣｐ－ＬＤ２复合材料棒之间未增强基体的塑性变形以及其对裂纹的阻断。

To overcome low toughness of metal matrix composites, a SiCp-LD2/LD2 composite with high fracture toughness, which is close to the fracture toughness level of related aluminum alloy, was fabricated by macro-structure-design method. Compared with a conventional SiCp/LD2 composite, strengthening effect of SiCp-LD2/LD2 composite is maintained and its fracture energy is highly increased. Its fracture procedure shows by stages, this prevents it from catastrophic fracture occurring in most conventional composites. Plajstic deformation of LD2 matriX between SiCp-LD2 composite bars with high volume fraction, crack's interdiction by unreinforced LD2 matrix and divarication along (SiCp-LD2)/(LD2) interface are the main toughening mechanisms of the structure-designed composite.