Using ARB process as a solution for dilemma of Si and SiCp distribution in cast Al-Si/SiCp composites

A major challenge in achieving the best potential of SiCp-reinforced aluminum composites is to homogeneously disperse SiC particles within the aluminum alloys. The presence of coarse Si fibers with non-uniform distribution in cast Al-Si alloys, which may lead to poor mechanical properties, is another important problem that limits the application of these alloys. In order to eliminate these problems, accumulative roll bonding (ARB) process was used in this study as a very effective method for improving the microstructure and mechanical properties of the Al356/SiCp composite. It was found that when the number of ARB cycles was increased, the uniformity of the Si and SiCp in the aluminum matrix improved, the Si particles became finer and more spheroidal, the free zones of Si and SiC particles disappeared, the porosity of composite decreased, the bonding quality between SiCp and matrix improved, and therefore mechanical properties of the composites were improved. The microstructure of the manufactured Al356/SiCp composite after six ARB cycles indicated a completely modified structure so that its tensile strength and elongation values reached 318 MPa and 5.9%, which were 3.1 and 3.7 times greater than those of the as-cast composite, respectively.