MECHANISMS OF REACTIVE WETTING - THE QUESTION OF TRIPLE LINE CONFIGURATION

This study is focused on the question of surface energy parameters det ermining the final, or steady-state, contact angle in reactive liquid- solid systems. Two possible configurations at the three-phase line are considered: (i) a continuous layer of reaction product extending only at the liquid-solid interface and (ii) a continuous layer also extend ing on the free surface of the substrate. In order to discriminate bet ween these configurations, wetting experiments are carried out in two reactive copper based alloy/vitreous carbon systems, as well as in the corresponding non-reactive systems. The general character of conclusi ons drawn from these experiments is discussed by calculating the therm odynamic barriers to the extension of reaction product layers over the free surface of the substrate. (C) 1997 Acta Metallurgica Inc.