纳米SiC颗粒增强镁基复合材料的动态断裂行为研究

Study on Behavior of Dynamic Fracture in SiC Nanoparticles Reinforced Magnesium Matrix Composites

采用机械搅拌与高能超声处理相结合的分散法制备了纳米SiC颗粒增强AZ91D镁基复合材料(n-SiCp/AZ91D),利用动态SEM原位拉伸方法研究了纳米复合材料的断裂行为。结果表明:微裂纹主要在晶界上的β-Mg17Al12处萌生,并沿着晶界上的脆性相不断开裂和连接向前扩展,由于颗粒和界面的阻碍,裂纹扩展路径较长。AZ91D合金的裂纹也主要沿着晶界上的脆性相不断向前扩展,但裂纹扩展路径比较平坦,AZ91D合金在加载初期就萌生出大量的裂纹。

Magnesium matrix nanocomposite reinforced with nano-sized SiC particles was fabricated by mechanical stirring and high intensity ultrasonic dispersion processing （n-SiCp/AZ91D）. The fracture behavior of n-SiCp/AZ91D composite has been observed by SEM in-situ tensile test. It is found that the crack initiation appeares in [3-Mg17A112 of the grain boundary initially. The main crack propagates along the fracture of brittle phase. Due to the cohesion of the matrix-particle interface is strong and the propagating cracks are impeded, the main crack propagation path is long. The crack of AZ91D matrix is formed by brittle phase cracking and then propagation along grain boundary. But crack propagation path is rather fiat. There were lots of crack appeared during the initiation of loading.