Diffusion in Metallic Melts

摘要

We present diffusion measurements in metallic melts measured by capillary techniques and results of molecular dynamic simulations. The investigated systems are the binary alioy AlNi2o and the multicomponent bulk glass-forming alloy Pd43Cii27NiioP2o. The temperature range of interest reached from the glassy state to the equilibrium melt. In the glassy as well as in the deeply supercooled state, below the critical temperature Tc of the mode-coupling, theory (MCT), diffusion is a highly collective atomic hopping process. Both investigated systems show around Tc a change in the diffusion mechanism. Above the liquidus temperature, diffusion in Pd43Cu27NiioP2o is a collective process whereas in AlNfeo the atoms diffuse probably by uncorrelated binary collisions. The influence of thermodynamic forces on diffusion in the liquid state of AIN120 can be described by the Darken equation with an additional temperature independent correction factor ("Manning"-factor).