Publication Date

5-4-2018

Department

Ames Laboratory; Materials Science and Engineering; Physics and Astronomy

Campus Units

Ames Laboratory, Materials Science and Engineering, Physics and Astronomy

OSTI ID+

1459544

Report Number

IS-J 9699

DOI

10.1016/j.intermet.2018.04.021

Journal Title

Intermetallics

Volume Number

98

First Page

131

Last Page

138

Abstract

Ab initio molecular dynamics simulations were performed to study the atomistic structures of Ni48Nb52, Ni59.5Nb40.5 and Ni75Nb25 liquids near their melting temperatures. It is found that the total coordination number only changes slightly across the compositions. However, there is significant difference in the chemical ordering. The Cluster Alignment method was used to identify the dominant local structure motifs. It is found that distorted and perfect icosahedral clusters are the most popular motifs around Ni atoms, while Z14, Z15, and Z16 Frank-Kasper polyhedra are dominant around Nb atoms. Among the three compositions, the eutectic composition (Ni59.5Nb40.5) has the largest population of these dominant motifs and the highest degree of five-fold local symmetry. Chemical order in the distorted icosahedral motif is studied and the occupation probability of Nb in the distorted region is found to be much different from other sites. The network formed by distorted and perfect icosahedral clusters and that by the interconnection of the perfect icosahedra, Z14, Z15, and Z16 motifs are the strongest at the eutectic composition. The high percentage of perfect and distorted icosahedral clusters and their strong network structures in this system (especially around the eutectic composition) correlate well with the excellent glass forming ability in this system.

DOE Contract Number(s)

AC02-07CH11358; 51671160; 51271149

Language

en

Department of Energy Subject Categories

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Publisher

Iowa State University Digital Repository, Ames IA (United States)

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