Ameliorating the Strength-Modulus Synergy in GNPs Reinforced Mg–Zn–Zr Composites via Multidirectional Forging and Hot Extrusion Deformation

The integration of lightweight and high-modulus magnesium-based materials is becoming increasingly valued as structural materials due to the complexity and intelligence of industrial products like automobiles and electronics. In this study, the graphene nanoplatelets (GNPs)/Mg–Zn–Zr composites with 0.5 wt% GNPs were successfully prepared by the combination of multidirectional forging (MDF) and hot extrusion (Ex). The newly-developed composites after multi-step deformation possessed excellent strength and modulus, with a tensile strength exceeding 375 MPa and an elastic modulus reaching 54 GPa. The results revealed that the stripping and thinning of GNPs bands parallel to the extrusion direction occurred after MDF + Ex, which promoted the dynamic recrystallization and the formation of numerous fine grains. The significant improvement in comprehensive mechanical performances of the composites could be primarily ascribed to the refinement of grain size caused by the optimized distribution of GNPs, and efficient load transfer facilitated by the tight interface.