Interfacial characterization of alumina-to-alumina joints fabricated using silver–copper–titanium interlayers

Two Ag–Cu–Ti interlayers with different compositions (Ag–35.3Cu–1.75Ti and Ag–26.7Cu–4.5Ti) were used to join sintered polycrystalline Al2O3 having different amounts of porosity to investigate the effect of titanium and porosity contents on evolution of interfacial chemistry and microstructures. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS) were used to characterize the interfacial microstructure. Two reaction layers, Ti2O and Cu3Ti3O, were found at the interface of Ag–Cu–Ti interlayers and Al2O3 using a series of simulated and experimental selected area diffraction patterns (SADP) of TEM and EDS. The total thickness of Ti2O and Cu3Ti3O reaction layers at the interfaces increases with increasing amounts of Ti in the Ag–Cu–Ti interlayers but is independent of the porosity content in the Al2O3. Two possible formation mechanisms of Ti2O and Cu3Ti3O reaction layers at the interface of Ag–Cu–Ti interlayers and Al2O3 have been proposed based on the interfacial characterization performed in the present study.