Interfacial properties and electron structure of Al/B4C interface: A first-principles study

• The heat of formation for B4C is calculated and the result is in good agreement with the experimental value.
• C-termination B4C (0001) surface is the most stable one and it is used to construct the Al/B4C hetero-interface models.
• The relaxed top-site (hollow-site-like) geometry has the best adhesion force and also be the most stable one.
• Electronic structure study show that AlC bond forms and Al4C3 compound possibly forms in the interface.

This research aims at investigating the structural, mechanical and electronic properties of the Al (111)/B4C (0001) interface by first-principles calculations. This model geometry Al (111)/B4C (0001) is chosen because the close-packed planes of Al and B4C have the (111) and (0001) orientation, respectively, and the lattice mismatch is only ∼2.1%. Among four B4C (0001) surfaces with different terminations, our calculation of surface free energies predicted that C-terminated B4C (0001) surface is the most stable one. Relaxed atomic geometries, the work of adhesion and interfacial free energies were calculated for three C-terminated B4C (0001)/Al (111) interfaces with different stacking sequences (top-site, hollow-site, and bridge-site). Results reveal that the relaxed top-site (hollow-site-like) Al/B4C interface has the best adhesion force and also be the most stable. The interfacial electron structure including charge density difference, Bader charge and density of states (DOS) is analyzed to determine the nature of metal/carbide bonding and we find the formation of AlC bond and possibly the formation of Al4C3 in the interface.