Processing of surface-treated boron carbide-reinforced aluminum matrix composites by liquid–metal stir-casting technique

Abstract

Boron carbide is one of the potential neutron-shielding materials and its use can be maximized for structural shielding application by dispersing it into metal matrixes such as aluminum. Dispersion of B₄C and its interfacial stability is a major issue during its processing. This investigation is on the synthesis of B₄C-reinforced 6061 aluminum matrix composite by liquid–metal stir-casting technique under optimized conditions after solving the issues related to the processing, and evaluation of the structural, mechanical, and interfacial characteristics. During processing of composites, pretreatment of B₄C particles is necessary to improve its dispersion. However, higher preheating temperatures above 300°C lead to particle agglomeration in the matrix due to the formation of B₂O₃ phase during preheating. B₂O₃ is formed due to the surface oxidation of B₄C particles above 300°C and this glassy phase leads to particle sintering and lump formation. Incorporation of particles preheated at 250°C has shown uniform distribution of particles in the composite. Interfacial characterization of the composite and the extracted B₄C particles from the matrix has shown the presence of interfacial reaction products such as AlB₂, Al₃BC, AlB₁₂, and AlB₁₀.