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Aluminum matrix composites (AMCs) reinforced with graphene nanoplatelets (GNPs) were fabricated by using an accumulative roll-compositing (ARC) process. Microstructure, mechanical and electrical properties of the nanostructured AMCs were characterized. The results showed that small addition (0.2 vol% and 0.5 vol%) of GNPs can lead to a simultaneous increase in the tensile strength and ductility of the GNPs/Al nanocomposites, as compared with the same processed pure Al. With increasing GNPs content, the tensile strength of the GNPs/Al nanocomposites can be enhanced to 387 MPa with retained elongation of 15%. Meanwhile, the GNPs/Al nanocomposites exhibited a good electrical conductivity of 77.8%–86.1% that of annealed pure Al. The excellent properties (high strength, high ductility and high conductivity) of the GNPs/Al are associated with the particular ARC process, which facilitates the uniform dispersion of GNPs in the matrix and formation of ultrafine-grained Al matrix. The strengthening and toughening of the GNPs/Al nanocomposites were discussed considering different mechanisms and the unique effect of GNPs.

Nanocomposite CrC/hydrogenated amorphous carbon (nc-CrC/a-C:H) coatings were deposited by a hybrid beams system comprised of a hollow cathode ion source and a cathodic arc ion-plating unit with varying H2 flow rates. The influences of H2 flow rates on the morphologies, microstructures, and properties of the coatings were systematically studied. The morphologies and microstructures of the coatings were characterized by SEM, AFM, XPS, Raman spectroscopy, GIXRD, and HRTEM. The mechanical and tribological properties were measured by a nano-indenter, scratch tester, and ball-on-disk tribometer. The wear tracks were evaluated using 3D profilometer, optical microscope, and EDS analysis. It has been found that a moderate H2 flow rate can effectively smooth the surface, enlarge the fraction of a sp3 bond, and improve the properties. The coating exhibits the highest hardness and elastic modulus at the H2 flow rate of 40 sccm. A superior combination of adhesion strength, friction coefficient, and wear resistance can be achieved at the H2 flow rate of 80 sccm.