Microstructure, mechanical properties and interfacial features of graphene oxide reinforced 7075 composites fabricated by ultrasonic assisted casting

Graphene oxide reinforced 7075 (GO/7075) composites were successfully prepared via ultrasonic assisted casting. In this study, the microstructure, mechanical properties and interfacial structure of GO/7075 composites with varying GO contents were investigated. The experimental results showed that GO could refine grain size and produce many dislocations at the GO/Al interface, and was well bonded with Al matrix. Meanwhile, a few rodlike Al4C3 phases were observed at the active prism planes of GO in the composite. When the content of GO reached 1.0 wt%, the optimal mechanical properties of GO/7075 composites were obtained. The yield strength and ultimate tensile strength of 1.0 wt% GO/7075 composites were 212.3 MPa and 285.6 MPa, which were 61.8 % and 41.1 % higher than those of 7075 alloy, respectively. The thermal mismatch strengthening and load transfer strengthening were the main strengthening mechanisms. Moreover, in order to control the interfacial reaction between GO and Al matrix, the thermodynamic/kinetic condition and growth mechanism for the formation of Al4C3 were analyzed in details.