Investigation On Liquid Structure Of Zn-based Binary And Ternary Alloys

Corrosion of metal materials brought great losses to the national economy, so the research of corrosion resistance of materials has been focused on. Zinc alloys with better mechanical properties and the wear-resistant antifriction performance than other materials, has been widely used. Zinc alloy has already relatively perfect processing conditions in actual production process, but the research of liquid structure of Zn based alloy is to explore the impact on the solid performance. The liquid structure of Zn based binary and ternary alloys were investigated by ab initio molecular dynamics simulations. We characterize the structure of melt though the pair correlation function, partial coordination number, Voronoi polyhedra as well as bond analysis, at the same time, we studied the kinetic properties--the diffusion coefficient.In order to study the relationship between FeZn13phase in zinc slag and the liquid structure, we select Zn95Fe5liquid alloy to calculate and simulate. The study of Zng5Fe5liquid alloy and zinc slag find that there was close contact between the liquid structure and the solidification structure. Portion of the clusters in the matrix structure is retained during the zinc slag solidification process. Voronoi polyhedra analysis indicates that the polyhedrons around the Fe atoms are mainly composed of10-12coordination polyhedrons. The structure of the cluster in the Zn95Fe5liquid alloy is similar with ζ phase (FeZn13), whic contains11-12Zn atoms around Fe atoms.Ab initio molecular dynamics simulation study shows that the interaction of the unlike atoms is strong in the Zn-rich, mainly composed of Zn-Fe coordination. The polyhedron with the coordination number of14and15is gradually transformed into the polyhedron with coordination number of12and13with the increase of Zn content. In this alloy system, the content of icosahedron is larger in zinc rich, so the order degree of liquid alloy is stronger, resulted Zn and Fe atom diffusion coefficient decreases in zinc rich. The diffusion coefficient of Zn atom is larger than that of Fe atom, the reason is that the icosahedron content for the center with Fe atoms have a high content of zinc atoms at the center of icosahedron.Zn-Bi alloy is a kind of good lead-free solder. In this paper, we adopt the molecular dynamics simulation method to study the liquid structure of near eutectic composition Zn-Bi alloy. The analysis result indicates that the interaction of unlike atoms is strengthen in the the eutectic point. Zn-Bi alloy melt structure is given priority to8-10coordination Voronoi polyhedrons. The topological structure of the eutectic point has obvious change in alloy melt, the content of7-9coordinate Voronoi polyhedra for the center with Bi atoms is lower, and10to13coordination polyhedron content increased significantly.We compare the structure of ternary alloys Fe5Zn90Bi5、Fe5Zn90Ni5with Fe5Zn95binary alloy to study the effect of the addition of third element on the structure of the alloy melt. The addition of Bi element could enhance liquidity of galvanizing zinc, while the addition of Ni element could effectively inhibit Sandelin reaction. The curves gij(r) show that the interaction of unlike atoms is stronge, mainly combine of Fe-Zn, Zn-Bi and Zn-Ni. The addition of the third element make NFeZn and NZnZn of two kinds of alloys increased at different extent, which indicates that the atoms of the chemical range order enhanced. Although the addition of Bi and Ni did not cause dramatic changes in topology structure around Fe atoms, there are still some <0,2,8,1> and <0,2,8,2> polyhedron change into <0,3,6,4> polyhedron. While the content of polyhedron around Zn atom slightly increased, the short-range order of Zn atom increased and reduces the diffusion coefficient of Zn atom. The interaction between iron and zinc atoms is stronger. As a result, the diffusion coefficient of Zn atom reduced and the diffusion coefficient of Fe atom increased. We think that is mainly caused by Fe-Zn chemical short range order.