Effect of reinforcement shape on fracture behaviour of SiC/Al composites with network architecture

Experimental results on metal-matrix composites (MMCs) with inhomogeneous reinforcement distribution confirmed the enhancement of the mechanical properties. Here three-dimensional network architecture, formed by particle- and rod-shaped SiC, was modeled and the effect of network structure on the strength and fracture was numerically investigated. The present specific network structural design enhances the 10 vol% SiC/Al composite, leading to a higher elastic modulus and yield stress in SiCrod/Al and SiCp/Al composite. The enhanced strength is attributed to the high load-transfer efficiency in the network composites: SiC walls parallel to the load direction carries a stress of 750-1000 MPa in SiCp/Al network composite, which is close to stress level of perpendicular SiC wall in SiCrod/Al network composite, and are higher than that in homogeneous composite (500 MPa). In SiCp/Al network composite, the main crack initiates in perpendicular SiC wall and then deflects to the matrix alloy, while the main crack initiates by rods fracture and propagates through perpendicular SiC walls in the SiCrod/Al network composite. The main crack is generated much earlier in SiCp/6061Al than in SiCrod/Al composites.