First-principles study of metal-carbide/nitride adhesion: Al/VC vs. Al/VN

We have performed density functional calculations to investigate the adhesion and electronic structure at interfaces between Al and the refractory transition metal nitrides/carbides VN and VC in order to understand the significance of the ceramic's metalloid component upon interfacial properties. We find that for both systems the preferred bonding site places the metal interfacial atoms above the ceramic's metalloid atoms, and that adhesion energies are comparable to those found for other metals (Ti, Ag) on MgO. The differences in magnitude and rank-ordering of the adhesion energies for the two interfaces are rationalized in terms of the the surface energies of the ceramics. Analysis of the charge density and density of states reveals that covalent Al-C/N bonds constitute the dominant metal-ceramic interaction.