First-principles study of Si doping effects on enhancing Al/Al₄C₃ interfacial bonding and suppressing Al₄C₃ growth

Aluminum-carbon composites often suffer from uncontrolled Al₄C₃ formation and weak Al/Al₄C₃ interfacial bonding, which degrade mechanical performance. This study systematically investigate how Si doping modulates both the Al/Al₄C₃ interface and Al₄C₃ growth kinetics using first-principles calculations. For the Al(111)/Al₄C₃(0001) interface, Si atoms preferentially occupy subsurface sites, and the C-terminated fcc conturation exhibits the strongest bonding (6.26 J/m²). Dual Si atom doping further enhances interfacial adhesion, with the optimal binding energy reaching 8.10 J/m² when both Si atoms reside in the third layer. In the bulk phase, Si doping significantly raises the energy barriers for carbon vacancy diffusion along the < 1210 > and [0003] directions—from 2.77 eV to 3.42 eV and from 3.84 eV to 4.71 eV, respectively. These changes imply that Si doping not only strengthens the metal/ceramic interface but also suppresses Al₄C₃ growth while promoting a higher aspect‑ratio morphology. This work provides a theoretical foundation for designing aluminum-carbon composites with optimized interfacial bonding and tailored Al₄C₃ morphology. • A single Si atom preferentially occupies subsurface sites. • Dual-Si doping preferentially occupies the third interfacial layers in C-termination. • Si doping increases C vacancy diffusion energy barriers, suppressing Al₄C₃ growth. • Si promotes formation of smaller but relatively high Al₄C₃ rod-like structures. • Si doping can enhance interfacial bonding and control the morphology of Al₄C₃.