MICROSTRUCTURAL CHARACTERIZATION OF INTERFACIAL REACTION-PRODUCTS BETWEEN ALUMINA AND BRAZE ALLOY

The Al2O3/STS3O4, Al2O3/Cu and Al2O3/Al2O3 joints were brazed in vacuu m with three types of Cu-Ag-Ti brazing filler metals at 1193 K for 1.2 ks. The effects of adherend metals on the microstructure and microche mistry of reaction products formed at the Al2O3/filler metal interface have been investigated. The reaction products of Al2O3/STS304 joints showed a layered structure consisting of TiO (monoclinic, a(0) = 0.585 nm, b(0) = 0.934 nm, c(0) = 0.414 nm), Cu2Ti4O (cubic, a(0) = 1.149 n m) and Fe2Ti4O (cubic, a(0) = 1.1297 nm). The TiO compound is a nonsto ichiometric titanium monoxide with composition range of TiO0.9 to TiO1 .1. Cu2Ti4O and Fe2Ti4O compounds can be considered as (Cu, Fe)(2)Ti4O because both of them have nearly the same crystal structure and latti ce constants. The reaction products of Al2O3/Cu and Al2O3/Al2O2 joints also showed a layered structure consisting of TiO and Cu2Ti4O. The Ti O compound was formed by redox reaction between Al2O3 and segregated t itanium, whereas Cu2Ti4O and Fe2Ti4O compounds formed by solid-state r eaction between TiO and copper from the brazing alloy and iron from th e adherend metals, respectively.