原位合成SiC对铝基复合材料微观组织和力学性能的影响

以铝粉、硅粉、石墨粉为原料, 通过冷压真空烧结原位合成了含不同质量分数SiC颗粒的SiC/Al-18Si复合材料。利用X射线衍射仪, 扫描电子显微镜和能谱分析仪等设备手段表征了铝基复合材料的相组成和微观结构, 研究了原位合成SiC对复合材料微观结构、抗弯强度和显微硬度的影响, 分析了复合材料力学性能的变化规律。结果表明: 复合材料的基体相为Al相, 第二相为Si相和SiC相; 原位合成的SiC颗粒弥散细小的分布在Al基体中, 其颗粒尺寸主要分布在0.2~2.8 μm, 具有亚微米、微米级的多尺度特性; 随着SiC质量分数的不断增加, 复合材料的显微硬度增大, 同时颗粒的平均尺寸仅由0.81 μm增大到1.13 μm, 但仍均匀分布, 正是这种尺寸稳定性, 使得SiC/Al-18Si复合材料硬度远大于Al-18Si; 当SiC质量分数为30%时, 材料的显微硬度最高, 达到HV 134, 相较于Al-18Si提高了88%。

Effect of SiC on the microstructure and mechanical properties of aluminum matrix composites by in-situ synthesis

SiC/Al-18 Sicomposites with different SiC content by mass were in-situ synthesized by cold pressing and vacuum sintering, using aluminium powders, silicon powders, and graphite powders as raw materials. The phase composition and microstructures of the aluminum matrix composites were characterized by X-ray diffractometer(XRD), scanning electron microscope(SEM), and energy disperse spectroscope(EDS). The effect of SiC on the microstructure, flexural strength, and microhardness of the composites were analyzed, and the variation in mechanical properties of the composites was discussed. In the results, the matrix phase of the composites is Al phase and the second phases are Siand SiC phases. The fine SiC particles by in-situ synthesis with the size ranging from 0.2 to 2.8 μm can be dispersed in Al matrix, showing the multi-scale characteristics of micron and submicron. With the increase in SiC content by mass, the microhardness of SiC/Al-18 Sicomposites increases;meanwhile, the average sizes of SiC particles increase from 0.81 to 1.13 μm, but the SiC particles are still uniformly distributed in Al matrix, making the microhardness of the SiC/Al-18 Sicomposites much higher than that of Al-18 Si. When the mass fraction of SiC is 30%, the microhardness of the SiC/Al-18 Sicomposites is the highest(HV 134), which is 88% higher than that of Al-18 Si.