Formation of Co-Si intermetallics in bulk diffusion couples. Part II. Manifestations of the Kirkendall effect accompanying reactive diffusion

The Kirkendall effect-induced migration of inert markers during a diffusion -controlled growth of Go-Si intermetallics was studied at 1100 degreesC. It is demonstrated experimentally that more than one Kirkendall marker plane call appear within the newly formed Co-silicide layers. It is also shown th at, under specific conditions, a marker plane cannot develop at all in any of the product phases. The marker behaviour is discussed in terms of the ve locity of the Kirkendall frame of reference relative to the laboratory-fixe d (Matano) frame. A phenomenological approach is presented to predict the n umber and positions of the Kirkendall marker planes developing in a multiph ase diffusion zone. (C) 2001 Elsevier Science Ltd. All rights reserved.