Transition from solid-solution softening to hardening in the plasticity of crystalline materials as a manifestation of quasi-localization of dislocation kinks

Abstract

The mechanical properties of materials are highly sensitive to the content of impurities and point defects due to their interaction with plastic deformation carriers-dislocations. This opens up the possibility to some extent control the mechanical properties of materials through alloying and creating solid solutions. In a number of crystalline materials, in addition to the well-known solid-solution strengthening in the region of a low concentration of solution atoms, the opposite behavior is also observed --- an increase of plasticity, or softening. In the present work, the mechanism of competition of these effects is revealed and it is shown how the boundary of behavior change can be used to estimate the microscopic parameters of materials. The theory predicts trends in the dependence of plasticity on the concentration of alloying elements, stress, temperature, strain rate, and a number of material parameters. Keywords: competition of solid-solution hardening and softening, dislocation kinks, random processes.