Microstructure and mechanical properties of Al–B₄C composite at elevated temperature strengthened with in situ Al₂O₃ network

This study evaluated the mechanical properties and thermal properties of Al–12 vol%B₄C composite at elevated temperature strengthened with in situ Al₂O₃ network. The composite was fabricated using powder metallurgy (PM) with raw materials of fine atomized aluminum powders, and the associated microstructures were observed. At 350 °C, the composite had ultimate tensile strength of UTS = 137 MPa, yield strength of YS_0.2 = 118 MPa, and elongation of ε = 4%. Besides, the mechanical properties of the composite remained unchanged at 350 °C after the long holding periods up to 1000 h. The excellent mechanical properties and thermal stability at 350 °C were secured by in situ am-Al₂O₃ network that strengthened the grain boundaries. The interfacial de-bonding and brittle cracking of B₄C particles were the main fracture mechanisms of the composite. In addition, the influence of sintering temperature and rolling deformation on the microstructures and mechanical properties was studied.