Strengthening behavior of few-layered graphene/aluminum composites

Strengthening behavior of composite containing discontinuous reinforcement is strongly related with load transfer at the reinforcement-matrix interface. We selected multi-walled carbon nanotube (MWCNT) and few-layer graphene (FLG) as a reinforcing agent. By varying a volume fraction of the reinforcement, aluminum (Al) matrix composites were produced by a powder metallurgy method. Uniform dispersion and uniaxial alignment of MWCNT and FLG in the Al matrix are evidenced by high-resolution transmission electron microscope analysis. 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, and the composites containing 0.7 vol% FLG exhibit 440 MPa of tensile strength.