Interfacial reactions in actively brazed Cu-Al₂O₃ composites and copper using a newly developed Cu-Sn-Ag-Ti filler alloy

Abstract

In dissimilar brazing, the differences in physical properties between the components lead to residual stresses. An active filler alloy Cu-20.5Sn-20Ag-3.5Ti was developed to braze the Cu-Al 2 O 3 composites (containing 25 and 50 volume pct. Al 2 O 3 ) to copper. Two mechanisms were proposed for chemical bonding as a result of alumina reinforcements reduction by the active titanium, including the formation of Ti 3 (Cu,Al,Sn) 3 O layer beside the Ti 2 O in Cu/Cu-25%Al 2 O 3 joints; and the solidification of Ti 3 (Cu,Al,Sn) 3 O in the vicinity of TiO layer/Cu 4 Ti islands in the Cu/Cu-50%Al 2 O 3 joints. Some intermetallic compounds such as Cu 3 Ti 2 and Cu 41 Sn 11 are formed/coarsened with an extra increase in brazing temperature. An increase in brazing time improves the thickness of the TiO x layer with no sensible effect on Ti 3 (Cu,Al,Sn) 3 O width.