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 accomp anied by sharp change of the electric conductivity. The expression for the work of formation of a nucleus of a new phase in a current-carryi ng conductor as a function of the geometrical parameters of the proble m is derived. The dynamics of the evolution of a macroscopic interphas e boundary when both phases form the coaxial cylindrical domains is in vestigated. It is shown that the character of equilibrium of an interp hase boundary depends upon the mutual location of phases with lower an d higher conductivity. If a low-conductivity phase occupies the extern al cylinder the position of the interphase boundary is stable. In the opposite case, namely when the low-conductivity phase occupies the int ernal cylinder, the position of the interphase boundary is unstable. I t 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 t o the axis of a conductor, the nuclei of a solid phase (high conductiv ity) may form inside it. The possible scenario of melting of the curre nt-carrying conductors is suggested.