Microstructural characterization of Al2O3/AISI 8650 steel joint brazed with Ag-Cu-Sn-Zr alloy

Sintered Al2O3 was brazed to AISI 8650 steel using a 67Ag-26Cu-5Sn-2Zr (wt. %) brazing alloy. The microstructure of the brazement and the interfacial p hase between the Al2O3 and brazement was investigated. The single ZrO2 laye r with a monoclinic structure was formed by the migration of Zr in the molt en brazing alloy to the Al2O3 surface, followed by a redox reaction between them. Small Ag and Cu particles were present in the reaction layer. The re mainder of the brazement formed a Cu-Ag eutectic alloy. Sn was homogeneousl y distributed within the brazement so that Sn-contained compounds were not formed within the brazement. The Al decomposed from Al2O3 diffused into the residual brazing alloy and AISI 8650 steel. (C) 2000 Elsevier Science B.V. All rights reserved.