Wettability and interfacial metallurgical behaviour of high temperature brazing alloys (PdCu-Ti) on alumina

By using the sessile drop method, the effects of additions on the wettability of a molten alloy Pd₄₈Cu₅₂ on alumina base substrates have been studied. The joining behaviour and the interfacial metallurgical behaviour were investigated. The results of experiments were analysed by means of thermodynamic theories. With the increasing of titanium content, the contact angles were decreased. So did the contact angles of the alloys with the decreasing of palladium content. Due to the addition of Ti in order to improve wettability, a double change at the interface took place: the formation of an adsorption layer rich in oxygen and titanium on the liquid side, than the formation of a titanium oxide layer on the solid side.