Abstract The development of many fields of science proves the usefulness of the interdisciplinary approach to the phenomena under investigation, based on the physical analogy of the described processes and their general laws. So, it is known the similarity of the relations obtained by J. Gibbs and A. Griffith for the critical size of the solid phase nucleus during crystallization and the critical size of crack at fracture. Both relations were derived from the energy balance condition. Taking into account that the J. Gibbs theory appeared almost a quarter of a century before the theory of A. Griffith, it cannot be ruled out that A. Griffith used the analogy between the critical crack initiation and appearance of critical nucleus of the solid phase. If this is true, then this analogy and the general thermodynamic approach to the process of fracture were extremely useful and led to the emergence of a new field of science – fracture mechanics. Hence follows the conclusion that the laws of mechanics and physics of fracture can be considered from the general positions of the theory of phase transitions, if we assume that the material is a two-phase one at the stable stage of fracture and consists of damaged and undamaged volumes. When critical conditions are reached, a "phase transition" occurs with the formation of a new phase: macrocrack. In the paper, this assumption will be confirmed by analyzing the processes of damage accumulation and crack growth under static and cyclic loading and changes in physical properties related with an increase in damage of material. It will also be shown that the known laws of fracture mechanics can be used to describe crystallization processes.