Reinforcement size effects on the abrasive wear of boron carbide reinforced aluminum composites

The use of ceramic nanoparticle reinforcements has shown significant promise for enhancing the mechanical properties of metal matrix composites due to the high specific surface area and superior intrinsic mechanical properties of nanoparticles. In this study, the effect of B4C reinforcement particle size on the abrasive wear behavior of Al-B4C composites was investigated. Composites with a homogenous dispersion of micrometric-B4C, submicron-B4C, and nano-B4C in a nanostructured Al alloy 5083 (AA5083) matrix were fabricated using cryogenic mechanical alloying and dual mode dynamic forging. Hardness was seen to increase with decreasing B4C reinforcement size, with the Al-nanoB(4)C composite exhibiting a 56% enhancement over unreinforced AA5083. The abrasive wear resistance of the Al-nanoB(4)C composite was 7% higher than the unreinforced AA5083. The other Al-B4C composites exhibited equivalent or reduced abrasive wear resistance as compared to AA5083. Analysis of the abrasive wear scars demonstrated that larger B4C reinforcements are prone to particle pull-out, thereby negating the benefit of higher hardness. The Al-nanoB(4)C composite has superior wear resistance due its high hardness and greater interfacial area, which hindered pull-out of nano-B4C particles.