title: Connection between the packing efficiency of binary hard spheres and the glass-forming ability of bulk metallic glasses.
abstract: We perform molecular dynamics simulations to compress binary hard spheres into jammed packings as a function of the compression rate R, size ratio α, and number fraction x(S) of small particles to determine the connection between the glass-forming ability (GFA) and packing efficiency in bulk metallic glasses (BMGs). We define the GFA by measuring the critical compression rate R(c), below which jammed hard-sphere packings begin to form "random crystal" structures with defects. We find that for systems with α≳0.8 that do not demix, R(c) decreases strongly with Δϕ(J), as R(c)∼exp(-1/Δϕ(J)(2)), where Δϕ(J) is the difference between the average packing fraction of the amorphous packings and random crystal structures at R(c). Systems with α≲0.8 partially demix, which promotes crystallization, but we still find a strong correlation between R(c) and Δϕ(J). We show that known metal-metal BMGs occur in the regions of the α and x(S) parameter space with the lowest values of R(c) for binary hard spheres. Our results emphasize that maximizing GFA in binary systems involves two competing effects: minimizing α to increase packing efficiency, while maximizing α to prevent demixing.
authors.affiliation: Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520, USA and Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520, USA.
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Department of Physics, Yale University, New Haven, Connecticut 06520, USA.
authors.forename: W Wendell
authors.initials: WW
authors.lastname: Smith
authors.affiliation: Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520, USA and Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520, USA.
authors.forename: Minglei
authors.initials: M
authors.lastname: Wang
authors.affiliation: Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520, USA and Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520, USA.
authors.forename: Yanhui
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520, USA and Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520, USA.
authors.forename: Jan
authors.initials: J
authors.lastname: Schroers
authors.affiliation: Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520, USA and Department of Physics and Benjamin Levich Institute, The City College of the City University of New York, New York, New York 10031, USA.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Shattuck
authors.affiliation: Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520, USA and Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520, USA and Department of Physics, Yale University, New Haven, Connecticut 06520, USA and Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA.
authors.forename: Corey S
authors.initials: CS
authors.lastname: O'Hern
mesh_terms: D005898:Glass / Q000737:chemistry*; D006244:Hardness; D008670:Metals / Q000737:chemistry*; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D044367:Phase Transition
chemical_list: D008670:Metals