Kirkendall void inhibition through the elimination of diffusivity mismatch assisted by nanocrystalline metal

Abstract

In this article, a general method for Kirkendall effect suppression has been proposed that harnesses the diffusivity enhancement effect brought by nanocrystalline metals. Through increasing the fraction of grain boundaries in the fast-diffusing species in the unbalanced diffusion couple, the flux of the slow diffusor can be enhanced through short-circuit diffusion, thus reducing the diffusivity gap, which is the root cause of the Kirkendall effect. Experiments have been performed on both Au-Cu and Au-Ag systems with successful results. A model has been established based on the Au-Cu system that predicts the diffusivity enhancement effect concerning the initial nanocrystalline Cu grain size.