Effect of hot extrusion temperature on the properties of gra-phene/Al–Zn–Mg–Cu alloy composites

Abstract In this study, 0.5 wt % GNPs reinforced Al–Zn–Mg–Cu matrix composites were prepared by vacuum hot pressing sintering and hot extrusion using Al–Zn–Mg–Cu alloy powder as matrix and graphene as reinforcing phase. The effects of different hot extrusion temperatures on the properties of the composites and the strengthening mechanism of Al–Zn–Mg–Cu matrix with graphene were studied. The results show that when the hot extrusion temperature is 420 °C, the extruded products have higher properties, and the tensile strength is 359 ± 2 MPa. This is because the increase of temperature will accelerate the diffusion rate of metal atoms, especially in the hot extrusion process, thus improving the extrusion quality of the products. It can be seen from the microscopic characterization that the black material after extrusion is distributed in a dispersed chain along the extrusion direction. With the increase of extrusion temperature, the graphene agglomeration improvement effect is better, and the orientation trend is more obvious. When the extrusion temperature is 420 °C, the dispersion traces are the most, the distribution is the most uniform and fine. The uniform distribution of graphene and the second phase (Mg 2 Si and MgZn 2 ) in the composites will be beneficial to the improvement of the mechanical properties of the composites. There are a large number of dimples and tearing edges in the tensile fracture of the composite extruded at 420 °C, and the dimples are more and smaller and equiaxed. The interfacial bonding between graphene and Al–Zn–Mg–Cu alloy matrix is better, and the graphene sheets are thinner and more evenly distributed, which is beneficial to the improvement of mechanical properties. At the extrusion temperature of 420 °C, the reinforcement of graphene aluminum matrix composites is evenly distributed and deformed, which is conducive to the formation of higher mechanical properties of the composites.