High-strength nanostructured Al/B4C composite processed by cross-roll accumulative roll bonding

In the present work, nanostructured Al/B4C composites were successfully produced in the form of sheets, through cross roll accumulative roll bonding (CR-ARB) process, at room temperature. The CR-ARB process was performed in two steps. In the first step, the strips were roll-bonded with a draft percentage of 66% reduction and for the next, the strips were roll-bonded with a draft percentage of 50%. The later step is consist of 8 rolling cycles, in which, after every rolling cycle the specimen was rotated 90, around normal direction of the rolling process, and then rolled again. The X-ray diffraction peak profile analysis was used to determine the crystallite size of the Al matrix in the various cycles. The results showed that CR-ARB process can effectively refine the coarse-grained structure to an ultrafine grain range, so that the crystallite size of the Al matrix of the composite produced by this process was determined to be about 110 nm. To evaluate microstructure of the produced composites, optical microscope (OM) was used. The results proved that the microstructure of the produced composite has a good degree of homogeneity in particles distribution and also a good bonding created between Al layers. To evaluate mechanical properties of the produced composites, their tensile strength was also determined in various rolling cycles and compared with the same composites produced by conventional accumulative roll bonding (ARB) process. (C) 2011 Elsevier B.V. All rights reserved.