Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7882645 | Acta Materialia | 2014 | 12 Pages |
Abstract
The dynamic properties and atomic configuration of Mg, Mg-Zn, Mg-Zn-Ca and Mg-Zn-Ca-Cu liquid and solid systems were comprehensively studied using ab initio molecular dynamics calculation. The viscosities of an Mg-Zn-Ca alloy were measured from 700 K to 960 K. It was found that Zn and Ca in Mg liquid induce remarkable slowing down of atoms, but Cu acted as a stimulus to the diffusion. Icosahedral short-range orders are most dominant in Mg-Zn-Ca alloys in view of the existence of a majority of 1551 type of bond pairs, ã0, 0, 12, 0ã type of Voronoi polyhedra. Icosahedral medium-range orders can be formed in Mg-Zn-Ca alloys by the perfect icosahedra via the linkage of vertex-, edge-, face- and intercross-shared atoms. It is suggested that the high glass forming ability of Mg-Zn-Ca alloys is essentially related to the sluggish mobility and strong icosahedral short- and medium-range ordering in the undercooled liquid.
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
Y.F. Zhao, D.Y. Lin, X.H. Chen, Z.K. Liu, X.D. Hui,