THERMODYNAMICS OF NUCLEATION IN CURRENT-CARRYING CONDUCTORS

This work studies the thermodynamics of phase transitions of the first kind in current-carrying conductors when these transitions are accompanied by sharp change of the electric conductivity. The expression for the work of formation of a nucleus of a new phase in a current-carrying conductor as a function of the geometrical parameters of the problem is derived. The dynamics of the evolution of a macroscopic interphase boundary when both phases form the coaxial cylindrical domains is investigated. It is shown that the character of equilibrium of an interphase boundary depends upon the mutual location of phases with lower and higher conductivity. If a low-conductivity phase occupies the external cylinder the position of the interphase boundary is stable. In the opposite case, namely when the low-conductivity phase occupies the internal cylinder, the position of the interphase boundary is unstable. It is shown that the current-carrying conductor melts from the surface at the temperature lower than the melting temperature. However, during propagation of the liquid (low-conductivity) phase from the surface to the axis of a conductor, the nuclei of a solid phase (high conductivity) may form inside it. The possible scenario of melting of the current-carrying conductors is suggested.