Interface compounds formed during the diffusion bonding of Al2O3 to Ti

The interfacial reaction products of Ti/Al2O3 joints obtained in the context of real diffusion bonding technology were investigated by means of X-ray diffraction analysis, X-ray photoelectron spectroscopy, and transmission electron microscopy. Some Ti reacted with Al2O3 giving titanium oxides, but the main mass transport occurred into the bulk Ti due to Al2O3 dissolution. The formation of a Ti[AI, O] solid solution followed by a order/disorder reaction yielded Ti3Al. Further Al enrichment at the interface could lead to the formation of TiAl, which was not observed in the present work due to either the short residence time at the bonding temperatures or to its lower oxygen solubility. For joints obtained at 800 degrees C and observation of shear test fracture surfaces it was ascertained that the crack always propagated within the Ti3Al layer. (C) 2000 Kluwer Academic Publishers.