Processing and characterization of graphene (Gr)-reinforced aluminium alloy 7075 (AA7075) microcomposites and nanocomposites are reported in this work. Composites are fabricated by mechanical alloying process at wet conditions. The bulk composites are prepared by uniaxial die pressing to get higher densification and sintered in an inert atmosphere. Density of the nanocomposites is higher than the microcomposites due to the reduction of grain size by increased milling time. X-ray diffraction (XRD) analysis confirms graphene interaction with the AA7075 matrix lattice spaces. The effective distribution of graphene with aluminium alloy is further confirmed by the Transmission Electron Microscopy (TEM) analysis. The hardness of the composites proportionally increases with the graphene addition owing to grain refinement. Wear morphology is characterized using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Microcomposites reveal abrasive and ploughing wear mechanism of material removal from the surface. Nanocomposites show adhesive wear with delamination and particle pull-out from the material surface.

    Abstract
    1 Introduction
    2 Materials and methods
    3 Results and discussion
        3.1 Density measurement
        3.2 Phase analysis
        3.3 Effect of graphene addition
        3.4 Hardness
        3.5 Tribological behaviour of the composites
    4 Conclusion
    References

• R. Ranga Raj(Department of Aeronautical Engineering, Sri Ramakrishna Engineering College)
• J. Yoganandh(Department of Mechanical Engineering, Sri Ramakrishna Engineering College)
• M. S. Senthil Saravanan(Department of Mechanical Engineering, Sree Buddha College of Engineering)
• M. S. Senthil Saravanan(Department of Mechanical Engineering, Sree Buddha College of Engineering)
• S. Sathiesh Kumar(Faculty of Material Science and Engineering, Jimma University)