Atomistic study of thermodynamic stability and fracture mechanisms in Al4C3(0001)/SiC(111) interfaces

• For interface models with different configurations, the work of adhesion and interfacial energies were calculated. • The uniaxial tensile properties of the interfaces were simulated using first-principles methods. • Surface energy scales with dangling bond density, while interfacial electronic reconstruction stabilizes high-energy surfaces into low-energy interfacial configurations. • Interfacial covalent bonds surpass metallic Al-Al bonds in strength, causing tensile failure within the Al 4 C 3 bulk rather than at the interface. • The interfacial strengthening mechanism was elucidated from both qualitative and quantitative perspectives through charge density difference, density of states (DOS) analysis, and Bader atomic charge analysis. Aluminum carbide (Al 4 C 3 ), as the primary interfacial precipitate phase in SiC-reinforced Al matrix composites, plays a significant role in the interfacial mechanical properties of these composites. A deep understanding of the interfacial bonding, stability, and micromechanical behavior of the Al 4 C 3 /SiC interface is crucial. This study employed first-principles calculations to systematically investigate the stability, mechanical behavior, and failure mechanisms of the Al 4 C 3 (0001)/SiC(111) interface. Through analysis of interfacial adhesion strength, electronic properties, and mechanical responses under loading conditions, we determined that the stacking configuration with C-terminated Al 4 C 3 and Si-terminated SiC possesses optimal stability and mechanical performance. The most stable interface exhibits superior work of adhesion (4.12 J/m 2 ) and minimal interfacial energy (1.87–––2.38 J/m 2 ), while simultaneously achieving the highest tensile strength and strain (10.9 GPa at 5 % strain). Moreover, the failure mechanism of the Al 4 C 3 (0001)/SiC(111) interface was found to be debonding initiated by the fracture of Al-Al bonds within the Al 4 C 3 phase. These findings provide atomic-scale insights into the interfacial structure and mechanical behavior of the Al 4 C 3 , SiC, and Al systems, serving as a guideline for the design, fabrication, and processing of advanced ceramic/metal composites.