Evolution of reinforcement distribution in Al–B4C composites during accumulative roll bonding

The distribution of reinforcement particles in the matrix of a composite is one of the most important microstructural features affecting properties. In this study, nanostructured Al–B4C composite sheets were processed by accumulative roll bonding (ARB), and the effect of the number of ARB cycles on the distribution of the B4C particles in the Al matrix was evaluated. From optical microscopic studies accompanied by the radial distribution function analysis, it was realized that the microstructure uniformity is improved by increasing the number of ARB cycles. It was in good agreement with bulk hardness measurements in which the standard deviation of the hardness values was decreased by progression of the ARB process. In addition, the X-ray diffraction peak profile analysis revealed that the area weighted mean crystallite size of the Al matrix decreases to the nanometric scale (114 nm) after seven ARB cycles.

► ARB developed a nanostructure in the matrix of the Al–B4C composite.
► An improvement in the reinforcement distribution was found by increasing ARB passes.
► By progression of ARB from one to seven passes, hardness increased from 60 to 82 HV.