The rapidly quenched Ag-Cu-Ti ribbons for active joining of ceramics

The technique of rapid quenching from the melt (planar flow casting method) was used to prepare active brazing Ag-Cu-Ti alloys with varying Ag and increased Ti content for joining alumina ceramics in form of ribbons 0.1 μm thick and 40 mm wide. Compositional optimization has been performed for high wetting and good spreading of the alumina substrate and for high strength of the joint. Microchemical and structural investigations of the reaction interlayer (alumina/Ag-Cu-Ti/alumina sandwich) have been performed using X-ray spectroscopy, EDX analysis, scanning electron microscopy (SEM) transmission electron microscopy (TEM) and electron diffraction (ED). The structure and local chemical composition profile of the reaction interlayer has been determined with respect to the distribution of Ag and Ti in the interface area. By TEM, it has been found that the reaction zone near alumina consists of TiO while the zone further from the alumina, rich in Ag-Cu contains mainly the mixture of Ti2O3 and Cu2O.