Cleavage toughness of single crystals

Griffith thermodynamic energy balance is employed to analyze cleavage phenomenon from atomic level. Results show that the cleavage toughness, the strain energy release rate, and the surface energy can be defined by the bond strength (the appropriate elastic modulus ) and the bond density. Such simple definition of fracture parameters is different from Irwin ones. This appropriate elastic modulus of single crystals is obtained using the complex variable function method. The calculated results of cleavage toughness and surface energy of typical ionic and covalent crystals by the present formulae are in excellent agreement with the experimental values. It demonstrates that our method offers a concise tool for predicting the cleavage toughness, the energy release rate and the surface energy of crystal cleavage planes.