基于实际三维微观结构研究颗粒混杂对SiC/AZ91D复合材料力学行为及其变形失效机理的影响-中国材料进展

文章信息/Info

Title:: Research on the Mechanical Behavior and Deformation Failure Mechanism of SiC/AZ91D Composites with Particles Mixing Based on Actual Three Dimensional Microstructure

Author(s):: CHEN Guoxin; YAO Junping; LIANG Chaoqun; LI Buwei; LI Yiran; School of Aeronautical Manufacturing Engineering, Nanchang Hangkong University, Nanchang 330000, China

Keywords:: particles mixing; SiC/AZ91D composites; finite element model; uniaxial compression; crack initiation

摘要:: 基于复合材料真实微观结构，在颗粒与基体界面引入内聚力单元，建立了3种不同颗粒混杂比增强的复合材料的有限元模型，模拟研究了SiC颗粒混杂的SiC/AZ91D复合材料单轴压缩时的力学行为及其变形失效机理。结果表明：等效粒径为5和10 μm的颗粒混杂增强的复合材料较单粒径颗粒增强的复合材料具有更高的屈服强度和抗压强度，压缩率介于两种单粒径颗粒增强的复合材料之间，颗粒混杂可以延缓复合材料裂纹萌生和裂纹扩展过程。随着5和10 μm的颗粒的体积混杂比增大，复合材料的屈服强度、抗压强度和压缩率也随之增加，颗粒混杂比越大，越有利于抑制裂纹萌生扩展，裂纹长度越长。颗粒混杂增强的复合材料裂纹萌生扩展机制是：颗粒群尖角处应力集中程度较高，导致基体受损形成微裂纹，这些微裂纹沿着最大切应力方向扩展，汇聚成主裂纹导致材料断裂。

Abstract:: Based on the real microstructure of the mixed particlesreinforced composites, the cohesive unit was introduced at the interface between the particles and the matrix, three finite element models with different particles mixing ratios were established, the mechanical behavior during uniaxial compression and deformation failure mechanism of the SiC/AZ91D composites were studied. The results show that the yield strength and compressive strength of the mixed particles-reinforced composites with equivalent particle sizes of 5 μm and 10 μm are greater than those of the single-particle reinforced composites, and the compression ratio is in the range of those of the two single-particle reinforced composites, particles mixing can delay the initiation and propagation of cracks in composite materials. The larger the 5 μm particle and 10 μm particle mixing volume ratio, the higher the yield strength, compressive strength and compression ratio of the composite; with the particle mixing volume ratio increasing, the initiation and propagation of cracks are more suppressed, the final crack length is longer. The mechanism of crack initiation and propagation of the composite materials is due to the serious stress concentration at the boundary and sharp corner of SiC particles group,resulting in matrix damage and microcrack initiation, and microcracks propagate and converge into main crack along the maximum shear stress direction.