Microstructure and properties of graphene nanoplatelets reinforced AZ91D matrix composites prepared by electromagnetic stirring casting

Graphene nanoplatelets (GNPs) reinforced AZ91D (GNPs/AZ91D) composites were prepared by semi-solid electromagnetic stirring casting. The microstructure, mechanical properties and strengthening behavior of the composites were investigated. Two types of bonding interfaces were found in the composites: the GNPs/Mg and the GNPs/MgO interface. The GNPs/Mg interface has a high degree of lattice distortion and few dislocations. In contrast, the GNPs/MgO interface has lower lattice distortion and more dislocations. GNPs with different failure modes were found on the fracture surface. According to the simulation, the strength of GNPs parallel to the stretching direction is 9.8 × 103 MPa, while the strength of GNPs perpendicular to the stretching direction is 0.5 × 103 MPa. This indicates that the stretching direction and fracture mode of GNPs affect the mechanical properties of the composites.