Fracture properties of interfacially doped Nb-Al2O3 bicrystals: II, relation of interfacial bonding, chemistry and local plasticity Original Research Article

As described in part I, Nb and α-Al2O3 single crystals were diffusion bonded in UHV for several different orientations of the two constituents. These were doped to give defined levels of interface coverage of Ag, Ti, Y or S. The influence of these dopants on the fracture behaviour of the several metal–ceramic interfaces was studied. Submonolayer doping causes large changes in fracture energy Jc: a strong reduction with Ag, and especially S; possibly, a small decrease with Y; and, in contrast, enhancement with Ti. Auger electron spectroscopy data indicated that the interfaces have excess oxygen and provided information on the bonding states and the local crack path.