基体合金种类对SiCw/Al复合材料拉伸性能的影响

The Influence of Matrix Alloy on the Tensile Property of SiCw/Al Composite

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 hot extrusion of SiCw/LD2 and SiCw/LC9 composites was carried out in this paper. The longitudinal tensile experiment shows that the tensile strength of SiCw/LD2 composite is 590MPa, while the SiCw/LC9 composite reaches 750MPa. Results of SEM examination shows that the fracture are both tough fracture acted by shearing stress. It can also been observed clearly that many whisker are pulled out off the fractured surface in SiCw/LD2 composite. So the whisker below critical length-diameter ratio to be pulled out is the main reason for fracture. For SiCw/LC9 composite, the whiskers above critical length-diameter ratio to be pulled broken is the main fracture form. The difference of critical length-diameter ratio of the two materials is due to the different matrix, this is the essential reason why the tensile strength of SiCw/LC9 is higher than SiCw/LD2 composite.