Brazing Alloys Based on Ag-Cu System for Ceramic-Metal Joints

Four compositions of rapidly quenched ribbon brazing alloys based on the Ag-Cu-Ti (Ag-26.5Cu-1.5Ti, Ag-25Cu-5Ti) and Ag-Cu-Zr (Ag-26.5Cu-1.5Zr, Ag-25Cu-5Zr) sys-tems were produced. Initial ingots were synthesized by arc melting. Rapidly solidified ribbons, 50-100 μm thick, were then fabricated from homogenized ingots using a "Crystall-702" facility. A comparative analysis of the microstructure and phase com-position of both the ingots and ribbons was conducted using scanning electron mi-croscopy and X-ray diffraction. The analysis revealed the presence of Cu4Ti and CuTi intermetallic compounds in the Ag-Cu-Ti alloys, and AgCu4Zr and Zr2Cu in the Ag-Cu-Zr alloys. Rapid quenching was found to produce metastable structures and significantly refine the intermetallic phases. Microhardness measurements of the ingot and ribbon states demonstrated a substantial influence of processing route on me-chanical properties. The tensile strength of the ingots was also evaluated. Wetting an-gles of the rapidly quenched alloy melts on 99% Al2O3 (alumina) ceramic substrates under vacuum were determined. All produced ribbons, except for the Ag-26.5Cu-1.5Zr composition, demonstrated adequate wettability. Thus, these materials are considered promising for further research into heat-resistant metal-ceramic joints.