Graphite/Aluminum: An Evaluation of State-of-the-Art Material

The tensile and fracture toughness properties of a unidirectional, 28.3 volume percent graphite/aluminum composite have been measured and compared to boron/aluminum composites. The longitudinal and transverse tensile strengths in four-point bending were determined to be 105.6 ksi (728 MPa) and 7.19 ksi (49.5 MPa), respectively. The longitudinal strength is only slightly lower than that which would be expected from a boron/ aluminum composite of similar volume fraction. The low transverse tensile strength was shown to be the result of a very weak filament-matrix inter face. The apparent fracture toughness, K _c ', of this graphite/aluminum com posite was found to be 23.48 ksi √in (25.83 MPa √ m) which is consider ably higher than the fracture toughness of a boron/aluminum composite with similar volume fraction. While the reason for this unexpectedly high fracture toughness is not definitively identified, the evidence suggests that the source may be the low filament-matrix interface strength.