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

The wetting behavior in the TiC/(Cu-Al) system was studied by the sessile d rop method over the entire Cu-Al alloy concentration range. The experimenta l results show that the wetting evolution in the TiC/Cu system is controlle d by partial dissolution of the titanium carbide phase. The presence of oxy gen on the TiC surface strongly inhibits the interaction between the ceram ic and molten Cu, thus leading to non-wetting conditions. The improved wett ing 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 fro m its increased solubility in the Al-containing molten alloy. The wetting o f 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 releas ed 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 substr ate due to the evaporation of the Al2O sub-oxide at elevated temperature. A thermodynamic analysis of the systems under consideration is in good agree ment with the experimental observations. (C) 2000 Acta Metallurgica Inc. Pu blished by Elsevier Science Ltd. All rights reserved.