Microscopic origin of slow dynamics at the good glass forming composition range in Zr1-xCux metallic liquids

摘要

We have studied the structure and dynamics of a series of Zr1-xCux metallic liquids at temperatures of 1500 and 1300 K. We found that as the Cu composition increases, the Zr–Zr order undergoes considerable transition, which can be attributed to the different size of Zr and Cu atoms. The diffusivities of both Cu and Zr atoms become lower at the composition range corresponding to good glass forming region, i.e., 0.50≤x≤0.70. We found that the lower diffusivities for the intermediate composition range are correlated with the concentration of some specific clusters, including icosahedra, which can be screened out automatically and unbiasedly by using direct atomic dynamics analysis. Our analysis for the dynamic properties of high temperature liquids of ZrCu metallic alloys shows that the icosahedral clusters together with some other pentagon-rich Voronoi clusters are responsible for slowing dynamics. Cluster lifetime analysis indicates that the slow clusters mobility could be originated in their energy.