Time-dependent failure of silver-interlayer diffusion bonds between non-deforming base-metals.

摘要

Silver-interlayer diffusion-bonds, fabricated at low temperatures using planar-magnetron sputtering, exhibit very high tensile strengths. Earlier work has shown that these joints undergo delayed failure at relatively low tensile stresses at ambient temperature for the case in which plasticity occurs in the base materials. Failure apparently occurs by a microvoid coalescence mechanism at the bond interfaces. Delayed tensile failures were investigated in this study for the case in which the applied stress does not produce any plastic deformation in the base metal. Failure occurs and appears to be controlled by time-dependent plasticity within the silver interlayer, which is governed by the effective stress in the interlayer. The plasticity causes cavity nucleation and, eventually, interlinkage and failure. These findings are believed to be generally applicable to any thin interlayer bond, including those prepared by processes different than physical vapor-deposition. 25 refs., 5 figs.