Thermofluctuational Fracture Mechanism in Solids in the Presence of an Active Medium

The paper addresses an approach to the physical notion of failure of solids in the presence of an active medium (a destructive compound), which is based on two successive steps. The first one is to go from considering a body as an elastic or viscoelastic continuum to studying it as an atomic-molecular system. The second step that follows the investigation of the atomic structure is to take into account the influence of atomic motion in a solid during the study of mechanical properties of solids (at high temperatures, in a wide range of loading speeds, under cyclic and vibrational loads), which is based on the experimental data on ultimate strength and yield stress of metals. A mechanism of crack initiation in a loaded metal under the action of destructive compounds is discussed. The capillary and diffusional propagation of a molten liquid-metal compound along grain boundaries and structural defects in a solid metal in combination with the viscous flow of the melt over its surface are shown to dictate the crack propagation into metal structure. The pattern of the affecting destructive factor has been clarified.