Influence of a Hot Extrusion with Rectangular‐Section on Mechanical Properties and Microstructure of 0.5 wt% Graphene Nanoplate‐Reinforced Aluminum Composites

A hot extrusion process for obtaining rectangular cross‐sections is applied to a graphene nanoplate (GNP)‐reinforced aluminum (Al) composite (GNP/Al) composite. After extrusion, the GNP dispersion is more uniform and its layer number decreases, whereas the proportion of small grains increases; the composite and pure aluminum exhibit a typical extrusion texture. Distinct equiaxed grains, which are attributed to graphene presence, are visible on the composite section in the extrusion normal direction, whereas the pure aluminum presents spindle‐shaped grain in the same direction. Certain high‐disorientation angles are generated, indicating the occurrence of dynamic recrystallization during the extrusion process. The tensile strength of the GNP/Al composite is moderately improved (11.2%), whereas its plasticity increases insignificantly. This relative small enhancement is attributed to the relative small extrusion ratio. The amount of strength reinforcement (induced by hot extrusion) calculates by the shear lag model is in good agreement with the experimental results, indicating that the shear lag strengthening model can accurately predict the strengthening effect of the hot extrusion process.