Effect of electric fields on the formation of solid phase nuclei in metal melts

The effect of an electric field on the crystallization process of metallic materials is studied on the basis of the idea that the nuclei of the solid phase are formed as a result of nonadiabatic Landau–Ziner transitions and transitions due to vibrational degrees of freedom. It is assumed that the splitting of energy levels by an electric field leads to an increase in the probability of these transitions and the appearance of dynamic displacements, the amplitude of which is one of the order parameters that describe the crystallizing system. The second parameter of the order is the amplitude of elastic displacements, which characterizes the volume change during the phase transition. Based on the analysis of the equations of kinetics of formation and growth of solid phase nuclei for two order parameters, it is established that constant and pulsed electric fields lead to the fact that a static autosolithon, which corresponds to a solid phase embryo, is formed in less time than in the absence of a field. At the same time, with an increase in the amplitude value of the field strength, this effect increases. This is explained by the fact that the potential barrier between two stable states of the system decreases, and when the critical value of the field is reached, it completely disappears. The same effect occurs when the pulse duration increases at a constant amplitude. In the mode of a damped autosoliton, the electric field leads to a change in the type of this solution to an oscillating autosoliton, and then, with an increase in its intensity, to a static one. When switching to the oscillating autosolithon mode, the electric field also leads to a change in the type of this solution, first to a damped autosolithon, and then to a static one. In the case of diffusive phase transformations, which are described by a switching wave, the effect of an electric field leads to an increase in the propagation velocity of this wave. The established effect depends only on the amplitude of the pulsed electric field and does not depend on its duration.