CHARACTERISTICS OF SEVERAL CARBON-FIBER-REINFORCED ALUMINUM COMPOSITES PREPARED BY A HYBRIDIZATION METHOD

The properties and microstructures of several high-strength and high-m odulus carbon fibre-reinforced aluminium or aluminium alloy matrix com posites (abbreviated as HSCF/Al and HMCF/Al, respectively, for the two types of fibre) have been characterized. The composites evaluated wer e fabricated by pressure casting based on a hybridization method. It w as found that the strength degradation of high-modulus carbon fibres a fter infiltration of aluminium matrices was not marked and depended up on the type of aluminium matrix. However, the strength of high-strengt h carbon fibres was greatly degraded by aluminium infiltration and the degradation seemed to be independent of the type of aluminium matrix. The longitudinal tensile strength (LTS) of CF/Al composites was very different between HMCF/Al and HSCF/Al composites. The HMCF/Al composit es had LTS values above 800 MPa, but the HSCF/Al composites had only a bout 400 MPa. In contrast, the transverse tensile strength of the HSCF /Al composites, above 60 MPa, was much higher than that of the HMCF/Al composites, about 16 MPa. Chemical reactions were evident to the inte rface of high-strength carbon fibres and aluminium matrices. There was no evidence of chemical products arising between high-modulus carbon fibres and Al-Si alloy and 6061 alloy matrices. However, it was consid ered that some interfacial reactions took place in pure aluminium matr ix composites. Fracture morphology observation indicated that the good LTS of CF/Al composites corresponded to an intermediate fibre pull-ou t, whereas a planar fracture pattern related to a very poor LTS and fi bre strength transfer. The results obtained suggested that interfacial bonding between carbon fibres and aluminium matrices had an important bearing on the mechanical properties of CF/Al composites. An intermed iate interfacial bonding is expected to achieve good longitudinal and transverse tensile strengths of CF/Al composites.