Improved mechanical properties of GNPs/Al composites by eliminating alumina and obtaining a strong bonded GNPs-Al direct contact interface and Mg-rich phases

Abstract

The interface between Graphene Nanosheets and Aluminum (GNPs-Al) without carbide and transition layers is referred to as a direct-contact GNPs-Al interface. In this work, the GNPs-reinforced aluminum matrix composites are fabricated by ultrasonic casting process. The interfacial structure of GNPs-Al is investigated using transmission electron microscopy, and the strength of the fabricated direct-contact GNPs-Al interface is analyzed. The results identified the presence of weak amorphous aluminum oxide at the original GNPs-Al interface. The direct contact GNPs-Al interface was obtained by introducing Mg. The migration of Al atoms formed an Al/C mixing zone between GNPs-Al, which led to the enhancement of the interface strength. The average UTS value has improved by about 20.5% due to the optimization of the interface structure. The enhancement of strength at the same toughness is achieved by the load transfer of GNPs, bridging, and the enhancement of dislocation storage capacity by the Mg-rich phase. The present work provides a new reference for the reinforcement of cast aluminum alloys by GNPs.