Metal hetero-diffusion along the metal-ceramic interfaces: A case study of Au diffusion along the Ni-sapphire interface

Abstract We propose a new method for determining the hetero-diffusion coefficient of metals along the metal-ceramic interfaces. The samples for diffusion studies are produced by partial dewetting of thin metal film deposited on ceramic substrate, followed by the deposition of an ultrathin layer of a diffuser. The latter covers both the partially dewetted thin film and the dewetting holes exposing the substrate. During diffusion anneal, the diffuser penetrates from the triple lines along the film-substrate interface. We apply this method for studying the diffusion of Au along the Ni-sapphire interface. Our experiments yield the pre-exponential factor and activation energy of 2 . 217 − 2.208 + 535 × 10 − 6 m 2 s and 179 ± 33 kJ mo l − 1 , respectively. Our results demonstrate that in the examined temperature range (450 – 550 °C), interface diffusion is slower than grain boundary hetero-diffusion, but faster than bulk diffusion of Au in Ni.