The Microstructure And Dynamic Behaviors In Binary Liquid La-based Alloys

The microstructure and dynamic behaviors in liquid La-based alloys were investigated by multi-slice sliding cell technique and classic molecular dynamic simulations.And it mainly involves the evolution of microstructure,the temperature dependence of diffusion coefficients,the effect of dynamic cross correlation factor,the correlation between self-diffusion and inter-diffusion and the correlation between microstructure and diffusion behaviors.In liquid La₈₀Al₂₀ alloy,the inter-diffusion coefficients measured by multi-slice sliding cell technique suggested that the inter-diffusion behaviors was slower in this system and the activation energy of inter-diffusion was larger than other systems.The classic MD simulation results showed that the lighter and smaller Al atom abnormally moved slower than La atom at the lower temperatures due to the fact that there were more Al-centered icosahedron-like clusters.And in liquid La₈₀Ni₂₀ alloy,the percentage of Ni-centered icosahedron-like clusters was small so that the Ni atom moved faster than La atom.The value of dynamic cross correlation factor was less than 1 at the whole temperatures in both systems,which indicated that the dynamic cross correlation factor brought suppressed effect for the inter-diffusion behaviors.Macroscopically,the dynamic cross correlation factor represents the deviation of the real diffusion behaviors from the ideal diffusion behaviors.And microscopically,it closely related to the interplay between atoms.By computing the chemical short-range order parameters,we found that there was an attractive interplay between La-Al and La-Ni atoms,which caused the different motion tendency between different atoms,and finally led to the failure of Darken equation.And the relationships between the chemical short-range order parameter and the dynamic cross correlation factor could not be easily described by the simple linear relations.