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对SiCw/LD2、SiCw/LC9复合材料进行了热挤压加工并沿其纵向进行了拉伸对比试验。结果表明:SiCw/LD2的抗拉强度为590MPa,而SiCw/LC9复合材料的抗拉强度高达750MPa。SEM分析发现,上述两种复合材料均为切应力作用下的韧窝形断口,但SiCw/LD2的断口有明显的晶须拔出。低于临界长径比的晶须被拔出是SiCw/LD2断裂的主要形式;高于临界长径比的晶须被拉断是SiCw/LC9断裂的主要形式;基体合金的不同导致了复合材料具有不同的晶须临界长径比,这也是SiCw/LC9复合材料较SiCw/LD2复合材料有更高抗拉强度的根本原因。
The SiCw / LD2 and SiCw / LC9 composites were hot-extruded and compared in their longitudinal direction. The results show that the tensile strength of SiCw / LD2 is 590MPa, while the tensile strength of SiCw / LC9 composite is up to 750MPa. SEM analysis shows that the above two composites are all ductile fracture under shear stress, but the fracture of SiCw / LD2 has obvious whisker extraction. The whiskers with the critical aspect ratio were pulled out to be the main form of SiCw / LD2 fracture. The breaking of whiskers above the critical aspect ratio was the main form of SiCw / LC9 fracture. The different matrix alloys led to the formation of composite Have different whisker critical aspect ratio, which is also the fundamental reason for higher tensile strength of SiCw / LC9 composite than SiCw / LD2 composite.