KINETICS OF INTERLAYER FORMATION ON POLYCRYSTALLINE ALPHA-AL2O3 COPPER-TITANIUM ALLOY INTERFACE

Copper-titanium alloys are known to wet an alumina surface. Traditiona lly, contact angles are used as measurable parameters to monitor the p rogress of wetting. Contact angle is a measure of the thermodynamic eq uilibrium at the interface. For reactive wetting systems, it is well k nown that the interfacial properties vary as a function of time. In th e present study, kinetics of reaction were studied by monitoring the r ate of interfacial phase formation. An immersion apparatus was built f or this purpose. The extent of reaction was measured by simple surface compositional analysis and by interfacial reaction layer thickness me asurements. The reaction layer exhibited a parabolic growth with an as sociated activation energy of 180 to 230 kJ/mole. A speculative growth mechanism is proposed based on the experimental observations and the information available in the literature.