On the Strengthening Mechanisms and Interfacial Characteristics of TiB₂/Hypoeutectic Al-Si Ceramic Composites

xTiB₂/Al-9Si composites were fabricated in this study using the mixed salt reaction method. With increasing TiB₂ particle content, the size of the primary α-Al grains decreased correspondingly. The best refinement of the primary α-Al grains was achieved with the addition of 4 wt.% TiB₂ particles, which resulted in the highest yield and tensile strength (172.3 and 255.3 MPa, respectively) and an elongation of 1.6%. In order to explore the TiB₂(\(\overline{1 } 1 0 0\))/α-Al(\(\overline{1} \overline{1} 1\)) interfacial structure and to understand the potential of the heterogeneous nucleation of α-Al grains on TiB₂ particles, the ideal work of adhesion (W_ad), electronic structure and bonding properties of the TiB₂(\(\overline{1} 1 0 0\))/α-Al(\(\overline{1} \overline{1} 1\)) interface were investigated utilizing density functional theory-based first-principles calculations. The calculation results demonstrated that the stacking model with a B-terminated interface had a relaxed interfacial distance of 2.093 Å, the work of adhesion of 1.24 J/m² and the interfacial energy of 0.09 J/m², thereby revealing the stability of this model. The calculated electron bonding indicated that strong and stable Al-B covalent bonds were generated at the interface, revealing the ability of α-Al grains to heterogeneously nucleate on TiB₂ grains and the positive contribution of TiB₂ particles to the grain refinement and strengthening mechanism of the Al-Si alloys. This study provides references for the in-depth study of ceramic particle-reinforced aluminum matrix composites.