Synergistic effect of Ag and C addition into Al–Cu matrix composites

The purpose of this paper was to design an Al–Cu–Ag–C material system to address the deterioration of mechanical properties caused by intermetallic compounds generated during Al–Cu sintering. The in situ pyrolytic C layer was encapsulated on the surface of the raw material particles, which prevented Al–Cu diffusion and reduced the generation of intermetallic compounds. The microstructure of the Al–Cu–Ag–C composites illustrates that several alloy phases of Al2Cu, Al4Cu9, and Ag2Al are formed. The addition of Ag significantly improved the mechanical properties of the composite due to the formation of the Ag2Al phase and Cu–Ag solution. The tensile strength and compressive strength of Al–52Cu–3Ag–C are increased by 123.9% and 64.9% over Al–52Cu–C, and the strain is also considerably improved. The strength enhancement derived from the Orowan strengthening contributed by Ag2Al, and the solid solution strengthening contributed by Ag–Cu solid solution, respectively. The presence of Ag2Al also enhances the hardness of the composite.