Modeling of the dislocation electroplastic effect in a single crystal using the molecular dynamics method

Abstract

The electro-plastic effect is a decrease in the resistance of metal crystals to deformation under the influence of a high-density pulsed electric current. Applying this effect allows deformation processing of relatively brittle metals without a sharp increase in temperature while reducing the probability of temperature negatively affecting the material. The paper discusses the influence of the electro-plastic effect on the change in the deforming force and the dislocations dynamics for a two-dimensional single crystal model based on the molecular dynamics method using the Morse potential. The authors propose a model implementing the electro-plastic effect by increasing the total kinetic energy of the system not uniformly over the entire crystal volume but depending on the potential energy of atoms. It is accepted that as a result of the electric current pulse traveling, the atom’s kinetic energy increases proportionally to the third degree of their potential energy. Atoms near defects have higher potential energy; therefore, the temperature will grow to a greater extent in the areas of defects, increasing their mobility. The authors simulated the motion of dislocations under the influence of shear stresses and temperature, considering the electric current pulse effect on the system. The paper describes the dependence of yield strength on temperature without taking into account the electro-plastic effect and then with it. The authors plotted the graphs of the dependence of the system’s kinetic energy on the frequency and the power of current pulses. The study shows that the electro-plastic effect sharply reduces the yield strength of a crystal, increasing the temperature in the system. It is caused by the fact that, besides general heating, the system is subjected to local heating of atoms near defects, which facilitates their motion.