Wetting of Al2O3 by Cu-xTi alloys at 1373 K

Wetting of Al2O3 by molten Cu-xTi alloys with wide composition range was deeply studied. The results show that the precipitation of TiO at the interface is depended on the Ti concentration in the alloys as well as the oxygen partial pressure in the atmosphere. When Ti concentration is lower than the critical Ti concentration, the wettability of the system is mainly determined by the precipitated TiO and the adsorption of Ti-O clusters at the interface; conversely, it is mainly determined by the adsorption of Ti-O clusters on the surface of alumina. For the spreading dynamics of: Cu-Ti alloys on the sapphire surface, the existence of two stages were observed: firstly, an initial fast spreading stage, which is mainly limited by the reaction rate of TiO precipitation; followed by a later slow spreading stage, which is mainly limited by the precipitation reaction of Al2O, and exhibits a stepwise spreading characteristic.