n-SiC_p/MB2复合材料组织与力学性能

Structure and properties of n-SiC_p/MB2 magnesium matrix composites

采用纳米级颗粒增强的镁基复合材料可望比微米级复合材料具有更好的力学性能。采用纳米n SiCp作为增强体,复合粉体经机械合金化、真空热压和热挤压得到了致密的n SiCp/MB2镁基复合材料。进行了热挤压态组织观察,测试了挤压态复合材料的气孔率、硬度、常温和高温力学性能。结果表明:制备的n SiCp/MB2复合材料致密且SiCp分布均匀,增强体/基体界面结合良好,基体中无明显的位错,基体晶粒尺寸小于300nm;复合材料的硬度、常温和高温力学性能比基体合金的高,但塑性下降;复合材料拉伸断口存在韧窝,高温拉伸断口上的韧窝更深。

n-SiC_p/MB2 magnesium matrix composites are fabricated by mechanical alloying, vacuum hot-press and hot extrusion, because it is possible that the composites may have better properties for using smaller nanoparticles as reinforcement. The cavity, hardness, mechanical properties at room and elevated temperatures of the as-extruded composites were tested. Microstructural observation shows that the SiC nanoparticle is uniformly distributed, the n-SiC_p/Mg interface is bonded very well, and there are no microcavity, reactive product and dislocations in the matrix alloy near the interface area. The grain size of n-SiC_p/MB2 composites is smaller than 300 nm and also smaller than that of MB2 alloy. Hardness, tensile properties at room and elevated temperatures of the as-extruded composites are higher than those of MB2 alloy; but the plasticity decreases. Small size dimples and little amount of SiC_p are obsreverd on the fracture surface, and the dimples become more deep with the tensile temperature increasing.