An empirical model for ideal work of adhesion: transition-metal aluminidesand silicides

The role of atomic bonding in the brittle fracture of intermetallic alloys has been assessed theoretically. A simple empirical model is proposed for t he ideal work of adhesion, resulting from a rigid-body separation, in terms of four variables, viz. the elastic stiffness constant, the equilibrium in terplanar spacing, and two scaling length parameters. The ratio of these tw o length parameters is assessed based on the available results of ab initio slab-supercell calculations. Ideal cleavage energies and critical stress i ntensity factors of transition-metal aluminides and silicides are estimated , and the results are discussed by comparing with the available experimenta l data of brittle fracture. The difference between the proposed model and o ther models, temperature dependence of surface energies, and an extension o f this model for interfacial adhesion are also discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.