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

CH Qiu and YS Su and JY Yang and XS Wang and BY Chen and QB Ouyang and D Zhang, COMPOSITES PART B-ENGINEERING, 220, 108996 (2021).

DOI: 10.1016/j.compositesb.2021.108996

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 microzones 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.

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