Numerical Study on Mechanical Properties of Quasi-Continuous SiCp/Al Network Composites with Various Particle Size Ratios (PSRs)

Recent works verified that network reinforcement design enhanced the modulus and strength of discontinuously reinforced metal-matrix composites (MMCs). The particle size ratio (PSR), i.e., the ratio of matrix to reinforcement particle diameters, defines the particle clustering degree and is an important network parameter. The effects of PSR on the mechanical properties of network SiCp/Al composites were studied via finite element analysis. The results showed that the composites with PSR ≤ 7:1 exhibited similar mechanical property. In contrast, composites with PSR ≥ 8:1 showed enhanced modulus (87.5-89.5GPa) and yield strength (303-315MPa) over homogeneous composites (modulus 75.9GPa and yield strength 299MPa). The enhanced mechanical properties were attributed to the higher load-bearing capacity of the reinforcement walls parallel to the load direction (PaW). However, premature failure and thus reduced elongation occurred with PSR ≥ 7:1 because network layers perpendicular to the load direction (PeW) acted as crack propagation paths. So, a threshold PSR of 7:1-8:1 was proposed for effective network design. The sacrifice of elongation needs to be solved for optimized network architecture designs.