Mechanical and tribological characterization of nanostructured graphene sheets/A6061 composites fabricated by induction sintering and hot extrusion

Abstract

An aluminum alloy (A6061) reinforced with graphene nanosheets (GNSs) was successfully fabricated by ultrasonic processing, high-frequency induction heat sintering (HFIHS), and hot extrusion. Harmful aluminum carbide (Al4C3) was not formed during HFIHS process as well as GNS particles were found to be able to stimulate recrystallization, restrict grain growth, and disturb the preferential texture in the present work. Enhancements in compressive strength of up to 50.4%, Vickers hardness of 13.3% as well as a 21.7% reduction in the friction coefficient along with a 17.2% reduction in the wear rate compared with those of as-extruded A6061 were measured. These improvements were due to the homogeneous dispersion of 0.25 wt% GNSs in the matrix. In addition, the yield strength predicted using modified model was in good agreement with the experimental results reported in this study. However, deterioration of the mechanical properties of the composites and a discrepancy between the theoretical prediction and experimental values occurred with the addition of 0.5 wt% GNSs owing to GNS agglomeration. This study demonstrated that the incorporation of an appropriate amount of GNSs can enhance the overall properties of a metal matrix, opening up an innovative design concept for fabricating bulk metal matrix composites (MMCs).