Mechanical behavior and interfacial micro-zones of SiCp(CNT) hybrid reinforced aluminum matrix composites

Abstract

Micro-sized silicon carbide particles (SiCp) reinforced aluminum (Al) matrix composites have been widely used in the aerospace, electronics and transportation applications. However, due to the easily formed stress concentration in the SiCp/Al interfacial micro-zones, the large-sized SiCp may cause serious plastic loss of SiCp/Al composites that have limited their applications. In this study, the 14.5 μm SiCp was selected to prepare the SiCp(CNT) hybrid reinforcement, and then the 15 wt. % SiCp/Al and SiCp(CNT)/Al composites were fabricated by the vacuum hot-pressing sintering, respectively. Compared to the SiCp/Al composite, the SiCp(CNT)/Al composites own the larger mechanical properties such as the Young's modulus, the yield strength and the tensile strength. Among these composites, the SiCp(0.5CNT)/Al composite presents the best matching of strength and plasticity as a result of the existence of CNTs in the SiCp/Al interfacial micro-zones. Strengthening and toughening effects of CNTs in the SiCp/Al interfacial micro-zones can contribute to: 1) increasing the punched zone size around the SiCp; 2) increasing the dislocation density in the SiCp/Al interfacial micro-zones; 3) changing the dislocation distributions in the SiCp/Al interfacial micro-zones; 4) pinning the dislocation movements by CNTs in the SiCp/Al interfacial micro-zones. From the analysis above, the strengthening and toughening mechanism of the CNTs introduced in the SiCp/Al interfacial micro-zones of SiCp(CNT)/Al composites can be revealed, which can be further developed to guide and prepare the hybrid particles reinforced metal matrix composites. • The strength-plasticity matching relationship of SiCp/Al composites can be improved by the presence of CNTs at the interface micro-zones. • Compared with SiCp/Al composites, the introduction of CNTs can increase the dislocation density at the interface micro-zones and pin the dislocation movement. • The existence of CNTs can change the dislocation distribution of SiCp/Al interface micro-zones.