Phase Formation via Electromigration

Diffusion processes taking place in such systems have to be regarded as processes that take place in thin Aims, and not in bulk samples. Reactive diffusion in thin Aims differs from that in the bulk case IMCs are formed in sequence ( one by one ), so that the phase spectrum of the diffusion zone differs from the full list of stable intermediate phases. Besides, the growth of new phase layers very often demonstrates a linear time dependence rather than a parabolic one. The best known theory providing an explanation for this fact was offered by Gosele and Tu [9]. However, it was shown that the linear stage of intermetallic layer growth may also be caused by a finite relaxation rate of nonequilibrium vacancies at these interfaces [lOj. 

Diffusion-Controlled Solid State Reactions. Andriy M. Gusak Copyright 2010 WILEY-VCH Verlag GmbH Co. KGaA. Weinheim ISBN 978-3-527-40884-9 

To analyze phase formation at direct currents (DG) imposed on a binary system (Section 8.4), we consider nonequilibrium vacancies and electric current effects simultaneously. Such an approach was first applied to interdiffusion processes in an electric field in solid solutions by Gurov and Gusak [14]. 

Theory of Phase Formation and Growth in the Diffusion Zone at interdiffusion in an Externai Eiectric Fieid 

Phase formation and growth in the system Au-Al in an external electric field was studied in [15, 16]. The magnitude and direction of the current were proved to have a strong influence on the phase composition of the diffusion zone, and on the growth kinetics of phase layers. The influence of an electric field on phase formation in the diffusion zone was also found in the Ca0-Al203 system [17]. 

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