ELECTROCHEMICAL PHASE-FORMATION INVOLVING MULTICOMPONENTS - HEMISPHERICAL OVERLAP MODELS FOR VARIED NUCLEATION AND GROWTH-CONDITIONS

The phenomenological theory of hemispherical growth in the context of phase formation with more than one component is presented. The model d iscusses in a unified manner both instantaneous and progressive nuclea tion (at the substrate) as well as arbitrary growth rates (e.g. consta nt and diffusion controlled growth rates). A generalized version of Av rami ansatz (a mean field description) is used to tackle the ''overlap '' aspects arising from the growing multicentres of the many component s involved, observing that the nucleation is confined to the substrate plane only. The time evolution of the total extent of macrogrowth as well as those of the individual components are discussed explicitly fo r the case of two phases. The asymptotic expressions for macrogrowth a re derived. Such analysis depicts a saturation limit (i.e. the maximum extent of growth possible) for the slower growing component and its d ependence on the kinetic parameters which, in the electrochemical cont ext, can be controlled through potential. The significance of this mod el in the context of multicomponent alloy deposition and possible futu re directions for further development are pointed out.