Wetting phenomena in the TiC/(Cu-Al) system

The wetting behavior in the TiC/(Cu-Al) system was studied by the sessile drop method over the entire Cu-Al alloy concentration range. The experimental results show that the wetting evolution in the TiC/Cu system is controlled by partial dissolution of the titanium carbide phase. The presence of oxy gen on the TiC surface strongly inhibits the interaction between the ceramic and molten Cu, thus leading to non-wetting conditions. The improved wetting of the oxygen-free TiC substrate by Cu-Al alloys is due to the enhanced transfer of titanium from the carbide phase into the melt, and results from its increased solubility in the Al-containing molten alloy. The wetting of TiC substrates covered with an oxygen-containing layer by a molten Cu-Al alloy is affected by the reduction of this layer and transfer of the released Ti into the molten metal. Enhanced wetting may also result from in situ deoxidization of the surface of the Cu-Al liquid drop and of the TiC substrate due to the evaporation of the Al2O sub-oxide at elevated temperature. A thermodynamic analysis of the systems under consideration is in good agreement with the experimental observations. (C) 2000 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.