Microstructure and tensile properties of 2014 Al alloy reinforced with continuous carbon fibers manufactured by gas pressure infiltration

Gas pressure infiltration method was used to prepare a composite consisting of unidirectional Ni-coated carbon fibers (Cf) in 2014 Al alloy matrix. The microstructure of the composite produced showed a full infiltration of molten aluminum alloy and evenly distributed fibers with a volume fraction of 30 vol%. Also, there was no sign of fiber clusters or residual porosity. The fiber-matrix interface was smooth with no discontinuities. Energy dispersive X-ray analysis (EDXA) results of the composite microstructure revealed no sign of significant reaction at the interface between the fibers and aluminum matrix alloy. Compared to the aluminum matrix alloy, the composite exhibited significant increases in modulus and ultimate tensile strength. However, the elongation to failure of the composite was considerably reduced. Moreover, the tensile modulus and ultimate tensile strength were in good agreement with the values predicted by the simple rule of mixture due to the strong interfacial bonding and absence of fiber strength degradation during composite preparation. SEM micrographs of the composite fracture surface showed that fracture took place mainly in the relatively weak aluminum alloy matrix, in comparison to the interfacial and fiber strengths, by void nucleation, growth, and shearing of the fibers.