Effects of temperature and grain size on diffusivity of aluminium: electromigration experiment and molecular dynamic simulation.

Understanding the atomic diffusion features in metallic material is significant to explain the diffusion-controlled physical processes. In this paper, using electromigration experiments and molecular dynamic (MD) simulations, we investigate the effects of grain size and temperature on the self-diffusion of polycrystalline aluminium (Al). The mass transport due to electromigration are accelerated by increasing temperature and decreasing grain size. Magnitudes of effective diffusivity ( D eff ) and grain boundary diffusivity ( D GBs ) are experimentally determined, in which the D eff changes as a function of grain size and temperature, but D GBs is independent of the grain size, only affected by the temperature. Moreover, MD simulations of atomic diffusion in polycrystalline Al demonstrate those observations from experiments. Based on MD results, the Arrhenius equation of D GBs and empirical formula of the thickness of grain boundaries at various temperatures are obtained. In total, D eff and D GBs obtained in the present study agree with literature results, and a comprehensive result of diffusivities related to the grain size is presented.