Empirical model for ideal work of adhesion: Transition-metal aluminides and silicides

The role of atomic bonding in the brittle fracture of intermetallic alloys has been assessed theoretically. A simple empirical model is proposed for the ideal work of adhesion, resulting from a rigid-body separation, in terms of four variables, viz. the elastic stiffness constant, the equilibrium interplanar spacing, and two scaling length parameters. The ratio of these two length parameters is assessed based on the available results of ab initio slab-supercell calculations. Ideal cleavage energies and critical stress intensity factors of transition-metal aluminides and silicides are estimated, and the results are discussed by comparing with the available experimental data of brittle fracture. The difference between the proposed model and other models, temperature dependence of surface energies, and an extension of this model for interfacial adhesion are also discussed.