PLASTICITY AT MULTIPLE LENGTH SCALES IN METAL-CERAMIC INTERFACE FRACTURE

Measurements of local plasticity in fracture of Ni-sapphire interfaces exhibit deformation on several length scales. The deformation process es are manifest as morphology on the surface of the Ni side of the fra cture surface that carl be quantified with scanning probe microscopies . Four scales of deformation are observed: ligamentary bridging, crack tip blunting, slip step formation and nanometer scale roughness. The relative amount of energy dissipated in each mechanism varies with int erface strength and density of precipitates. Since the most energy int ensive processes, i.e. ligamentary bridging and crack tip blunting, ar e associated with nano precipitates. large variations in interface tou ghness will he related to extrinsic factors.