Interfacial Modification Using Matrix Alloying in Mg/CNT Composites for Improved Mechanical Performance

Carbon nanotube (CNT)-reinforced magnesium (Mg) matrix composites were fabricated through a three-step preparation process which consists of mixed ball-milling, melt processing, and hot extrusion process. The results show that mechanical ball-milling well-dispersed CNTs on zinc flakes and uniform distribution of CNTs were obtained in the composites after melt processing and hot extrusion process. Aluminum (Al) with a mass fraction of 0.3% was added into the composite melt before casting so as to induce interfacial reaction on the surface of CNTs. Consequently, in comparison with Mg-6Zn/CNT composites, the yield strength and ultimate strength of Mg-6Zn-0.3Al/CNT composites increased by 21.1% and 9.3%, respectively. Unlike CNTs in the Mg-6Zn/CNT composites, a great amount of nanosized aluminum phases which were validated to be aluminum oxide (Al₂O₃) were found on the surface of CNTs in the Mg-6Zn-0.3Al/CNT composites. The interfacial reaction transformed the physical combination of CNT-Mg interface into reaction bonding which increased the efficiency of load transfer contributed by CNTs.