Development and performance evaluation of green aluminium metal matrix composites reinforced with graphene nanopowder and marble dust

Abstract Sustainable and high-performance composites have gained sufficient attention in recent years. In this regard, an attempt is made to develop aluminium metal matrix composites reinforced with graphene nanopowder and marble dust using the stir casting technique. Marble dust powder was kept constant at 0.5% in all composite samples, while graphene varied between 0.5 and 2.5%. This unique synergic combination of reinforcement shows improvement in the mechanical and tribological properties of composites. The optimum properties of the composites are recorded at 0.5% marble dust and 2% graphene nanopowder-reinforced samples. A maximum drop of 41% in wear rate was observed at 60 N loading conditions at a 0.63 m/s speed within a range of 20–100 N loading and 0.63 and 1.89 m/s rotational speed conditions. The specific wear rate also shows the same trend. The coefficient of friction values also decreased in the composite samples compared to the as-cast aluminium alloy. Toughness values decreased sharply in composite samples; however, a slight increase was observed as reinforcement increased, reaching 9J in the 0.5% marble dust and 2% graphene samples, which was 25% lower than the as-cast alloy sample. Microhardness is improved by 56.9% and tensile strength by 32.5% in the 0.5% marble dust and 2% graphene-reinforced sample, and elongation decreased by 33.7% in the 2.5 % graphene-reinforced sample. SEM characterization of fractured tensile and toughness samples reveals the nature of the failure of composites. SEM of the wear surface shows the wear behaviour of the composites. The overall findings demonstrate that the marble dust and graphene powder hybrid reinforcement offer an optimal balance between the mechanical and tribological properties along with sustainability, paving the way for next-generation green metal matrix composites.