高体积分数SiC_P/Al复合材料的拉伸、压缩与弯曲特性

Tensile,compressive and flexible properties of high volume fraction SiC_P/Al composites

对高体积分数碳化硅颗粒增强铝基(SiCP/Al)复合材料的拉伸、压缩和三点弯曲特性进行了实验研究。结果表明:高体积分数SiCP/Al复合材料与低体积分数SiCP/Al复合材料相比,没有明显的线性屈服阶段。进一步的加载-卸载实验表明,在外载荷作用下,材料宏观上呈现一种类似金属材料的塑性,卸载后留有较大的残余应变,再次加载时沿上次卸载路线上升,而且拉应力导致的残余应变大于压应力。三点弯曲时材料内部产生残余塑性变形的潜力最大,切线模量更稳定。宏观断口分析表明,金属基体的非均匀分布导致产生局部渐进的微屈服,是使材料性能宏观上类似塑性材料的主要原因。制备过程中的残余应力和基体内部的微缺陷是拉应力比压应力产生更大残余应变的主要原因。

The experiments were performed on tensile, compressive and flexible properties of high volume fraction SiCp/Al composites. The result indicates that the composites have no obvious linear yield process. Loading and unloading experiments were carried out. It is found that the macroscopic properties of this SiCp/Al composite are similar to plasticity of metal materials under external load. It has a quantity of residual strain on unloading, and the reloading course is approximately the same as the last unloading course. The residual strain caused by tension is greater than that by compression. The material has a stable tangent modulus with the best potential of residual plastic formation under three-point bending. From the analysis on SEM fractography, it shows that the local and gradual microyields of nonhomogeneous distribution of the matrix are the main reasons that get the behavior of high volume fraction SiCp/Al composites similar to that of plastic materials in macroscope. The residual stress in the process and microdefects in the matrix make the residual strain by tension greater than that by compression.