Strengthening behavior of few-layered graphene/aluminum composites

Strengthening behaviour of composite containing discontinuous reinforcement is strongly related with load transfer at the reinforcement-matrix interface. Few-layer graphene (FLG) as a reinforcing agent and aluminum (Al) as a matrix are selected, respectively. By varying a volume fraction of the FLG, Al matrix composites were produced by a powder metallurgy method. Uniform dispersion and uniaxial alignment of FLG in the Al matrix are evidenced by high-resolution transmission electron microscope analysis. The composite with only an addition of 0.7 volume fraction of FLG exhibits ~440 MPa of tensile strength. To investigate strengthening behaviour of the composite containing discontinuous reinforcement, multi-walled carbon nanotube (MWCNT) and FLG reinforced Al matrix composites are compared. In terms of load transfer, surface area of the reinforcement is significantly important, although the reinforcements have a similar molecular structure, FLG has a 12.8 times larger specific surface area per volume more than MWCNT due to geometric difference. Therefore an increment of a yield stress versus a reinforcement volume fraction for FLG shows 3.5 times higher than that of MWCNT. Consequently, for both reinforcements, the composite strength proportionally increases with the specific surface area on the composite.