Microstructural characteristics and mechanical behavior of SiC(CNT)/Al multiphase interfacial micro-zones via molecular dynamics simulations

Abstract Developing metal matrix composites (MMCs) with hybrid reinforcements becomes a promising approach to balance and improve their strengths and toughness. However, due to complexity of multiphase interfacial micro-zones and lack of suitable research method, difficulties are still existing in revealing the structure-property relationship of hybrid MMCs. In this work, molecular dynamics simulations are conducted to study microstructural characteristics and mechanical behavior of SiC(CNT)/Al multiphase interfacial micro-zones under uniaxial tensions. Six atomic-scale structural models of SiC/Ni/CNT, SiC/Al, SiC/Ni/CNT(l)/Al, SiC/CNT(l)/Al SiC/Ni/CNT(s)/Al and SiC/CNT(s)/Al (l: long, s: short) interfacial micro-zones are created, respectively. Compared with those of SiC/Al interfacial micro-zone, improved tensile ductility and toughness are achieved in the SiC/Ni/CNT(l)/Al, SiC/CNT(l)/Al, SiC/Ni/CNT(s)/Al and SiC/CNT(s)/Al interfacial micro-zones, where lots of dislocations, larger dislocation densities and continuously increasing equivalent shear strains appear. SiC/Ni/CNT(l)/Al and SiC/CNT(l)/Al interfacial micro-zones with long CNT clusters could produce large Young's modulus, while those of SiC/Ni/CNT(s)/Al and SiC/CNT(s)/Al interfacial micro-zones are relatively low caused by poorly load-transferring. Tensile fracture of SiC/Al interfacial micro-zone occurs at the SiC/Al interface due to the local concentrations of both dislocations and plastic deformation, while those of SiC/Ni/CNT(l)/Al, SiC/CNT(l)/Al SiC/Ni/CNT(s)/Al and SiC/CNT(s)/Al interfacial micro-zones all happen in the Al matrix close to the bottom ends of CNTs and SiC. From the analysis above, the microstructural characteristics and mechanical behavior of SiC(CNT)/Al multiphase interfacial micro-zones can be brought into light, which would be applied to design and fabricate smart multiphase MMCs.