SOLID-STATE BONDING OF SINGLE-CRYSTALS OF NI(111) AL2O3(0001)/

Some fundamental aspects of the solid state bonding process between si ngle crystals of alumina and nickel were studied. It was shown that a model formerly developed to account for the kinetics of diffusion bond ing between two metals can be adapted to the case of a metal-ceramic c ouple. A coincidence site lattice calculation proved that one of the c rystallographic relative orientations often mentioned in literature wa s certainly energetically favourable. With this relative orientation, several nickel-alumina bicrystals have been produced by solid state bo nding under secondary vacuum. The influence of operating conditions su ch as contact pressure and annealing duration has been explored and co mpared with the calculated results of the bonding kinetics model. Char acterization of the solid-state bonded interface was undertaken by opt ical microscopy and scanning as well as transmission electron microsco py. Observations prove that the initial imposed crystallographic relat ive orientation was maintained during the solid-state bonding process, and that the synthetic alumina-nickel interface obtained by this tech nique was free from reaction layer at the usual TEM scale.