Hot-roll bonding of aluminium matrix composites with different volume fractions of alumina

Metal matrix composites (MMC) with volume fractions of 0.08, 0.11 and 0.14 alumina (Al2O3) were fabricated by roll bonding. This low-cost approach to MMC manufacture has the flexibility of controlling the volume fraction of the MMCs by varying the oxide thickness on the anodized aluminium foil, and the number of layers of these foils to be sandwiched between plain aluminium sheet as the matrix metal. The fragmentation of the laminate alumina is achieved by a series of hot- and cold-rolling operations. The resulting reinforcing alumina particles have platelet shape measuring approximately 20 Μm×11Μm×5 Μm instead of a stringer shape as expected. It is found that the improvement in modulus and strength did follow very closely with the rule of mixtures. A small scatter of measured data, especially the resistivity of the MMCs, was observed. This can be explained by the inefficient bonding between the reinforcing alumina and the matrix metal as demonstrated later in this study.