MECHANICAL PROPERTIES, PHYSICS OF STRENGTH, AND PLASTICITY Synergetics of the Interaction of Mobile and Immobile Dislocations in the Formation of Dislocation Structures in a Shock Wave. Effect of the Stacking Fault Energy

A kinetic equation for the density of dislocations, which reflects the main stages of the formation of dislocation structures of different types in a shock wave, has been formulated based on the analysis of the interaction of two kinetic processes described by reaction-diffusion type equations for densities of mobile dislocations and dislocations forming immobile dipoles, respectively. It has been shown that an inhomoge� neous (cellular) dislocation structure is formed at relatively low pressures behind the front of a shock wave, whereas a uniform distribution of the dislocation density with stacking faults appears at high pressures. The transition from a cellular dislocation density distribution to a uniformly distributed dislocations with stacking faults depends on the stacking fault energy γD of the metal: the lower is the stacking fault energy, the lower is the pressure in the shock wave σc at which the cellular dislocation structure transforms into the structure with a uniform dislocation density distribution. It has been found that the dependence of the critical pressure on the stacking fault energy γ D is described by the law σ c ~ (γ D /μb) 2/3 (where μ is the shear modulus and b is the Burgers vector), which is confirmed in the experiment.