Accumulative press bonding; a novel manufacturing process of nanostructured metal matrix composites

A new manufacturing process for metal matrix composites has been invented, namely accumulative press bonding (APB). The APB process provided an effective method to produce bulk Al/10 vol.% WCp composite using tungsten carbide (WC) powder and AA1050 aluminum sheets as the raw materials. The microstructural evolutions and mechanical properties of the monolithic aluminum and Al/WCp composite during various APB cycles were examined by scanning electron microscopy, X-ray diffractometry, X'pert High-Score software, and tensile test equipment. The results revealed that by increasing the number of APB cycles (a) the uniformity of WC particles in aluminum matrix improved, (b) the porosity of the composite eliminated, (c) the particle free zones decreased and (d) the cluster characteristics improved. Hence, the final Al/WCp composite processed by 14 APB cycles showed a uniform distribution of WCp throughout the aluminum matrix, strong bonding between particles and matrix, and a microstructure without any porosity and undesirable phases. The X-ray diffraction results also showed that nanostructured Al/WCp composite with the average crystallite size of 58.4 nm was successfully achieved by employing 14 cycles of APB technique. The tensile strength of the composites enhanced by increasing the number of APB cycles, and reached to a maximum value of 216 MPa at the end of 14th cycle, which is 2.45 and 1.2 times higher than obtained values for annealed (raw material, 88 MPa) and 14 cycles APBed monolithic aluminum (180 MPa), respectively. Though the elongation of Al/WCp composite lessened during the initial cycles of APB process, it increased at the final cycles of the mentioned process by 78%. Role of WC particles, uniformity of reinforcement, porosity, bonding quality of the reinforcement and matrix, grain refinement, and strain hardening were considered as the strengthening mechanisms in the manufactured composites. (c) 2013 Elsevier Ltd. All rights reserved.