Influence of oxygen on the interfacial bonding and mechanical properties in the particulate-reinforced aluminum matrix composites

The reinforcing effect of nanoparticles in aluminum matrix nanocomposites (AMCs) is often underestimated, primarily due to weak mechanical bonding at the nanoparticle-matrix interface. In this study, we investigate the role of oxygen in enhancing the mechanical properties of SiC nanoparticle-reinforced AMCs with the help of increased interfacial bonding. Aluminum powder incorporating oxygen was produced through the gas atomization, and thoroughly blended with 3 vol.% SiC nanoparticles using the mechanical milling. The composite powder was consolidated by the hot-pressing process at 500 o C under an applied pressure of approximately 270 MPa. As a result, SiC nanoparticles were uniformly dispersed within an Al-O matrix, referred to as Al-O/SiC composites. An interfacial layer with a higher oxygen concentration than the matrix was observed between the SiC nanoparticles and the matrix. The interfacial layer partitioned by the oxygen exhibited an expanded aluminum lattice, which did not lead to oxide formation. Furthermore, oxygen influenced the bonding states of aluminum and carbon, promoting a robust interface through atomic oxygen bridging. Consequently, the Al-O/3vSiC composites exhibited higher values of Vickers hardness ∼18% than the Al/3vSiC composites. • The Al-O/SiC composite was developed using the powder metallurgical routes, where Al-O alloy was employed as a matrix for the composite fabrication. • The interfacial layer containing oxygen was observed at the interface of the matrix and SiC nanoparticle. • The incorporated oxygen in the layer plays a critical role in promoting additional interfacial bonding in the Al-O/SiC composite. • The consequent mechanical properties of the Al-O/SiC composite are enhanced.