First-Principles Study of Interfacial Properties and Fracture Behavior of (3C and 4H) SiC/Al Interfaces

First-principles calculations based on density functional theory (DFT) are performed to investigate the interfacial properties and fracture behavior of 3C-SiC(111)/Al(111) and 4H-SiC(0001)/Al(111) interfaces. To mitigate surface effects through adequate slab thickness, the interface models are constructed by positioning a seven-layer Al(111) slab atop eight-layer 3C-SiC(111) and 14-layer 4H-SiC(0001) slabs, respectively. Accounting for the distinct surface terminations and stacking sequences of each polytype, six interface configurations are established: C-top, -center, and -hollow; Si-top, -center, and -hollow. Based on the simulation results of surface energy, work of separation, and electron density distribution, the C-top configuration yields the most stable SiC/Al interface structure, exhibiting the highest work of separation. The ultimate tensile strengths of the C-top interfaces are 6.603 GPa (3C-SiC/Al) and 6.851 GPa (4H-SiC/Al), with corresponding tensile strains of 10% and 12%, respectively. Tensile fracture initiates exclusively within the Al slab for all C-top interfaces, but at distinct atomic layers: fracture occurs between the second and third Al layers (Al2-Al3) for 3C-SiC/Al; and between the first and second Al layers (Al1-Al2) for 4H-SiC/Al. This distinction reflects the influence of different interfacial configurations on the bonding strength between aluminum atomic layers. In summary, an atomic-scale investigation of the interfacial properties and fracture behavior of SiC/Al interfaces provides critical insights for the design and fabrication of novel ceramic/metal composites.