Nanostructure of wetting triple line in a Ag-Cu-Ti/Si3N4 reactive system

Nanometer scale structures around wetting triple lines were studied in a Ag -Cu-Ti/Si3N4 reactive system. Changes in the contact angle and radius of th e molten metal on the substrate as a function of time were also measured in the system as macroscopic wetting behaviors. The macroscopic wetting behav iors showed two wetting stages and double layered reaction products consist ing of upper Ti5Si3 and lower TiN layers were observed in both first and se cond stages. The reaction product always lay in front, of the triple line d efined as a triple junction of Ag-Cu-Ti alloy/Ti5Si3/atmosphere. At the fro nt of the reaction product, a dominant phase changed from TiN in the first stage to Ti5Si3 in the second stage. It is considered that the structural c hange is one of the reasons why the macroscopic wetting behavior changed, a nd that the structural change was caused by a decrease of Ti activity as th e reactive wetting progressed. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.