Studies of Structural and Chemical Ordering in Metallic Liquids and Glasses Using Electrostatic Levitation

<p>Since the discovery of the first metallic glass in 1960, there has been a large research effort dedicated to understanding the glass transition and the formation of metallic glass from the supercooled liquid state. Knowledge of the relationship between the liquid's structure and its thermophysical and kinetic properties provide insight into why some metallic alloy liquids form glasses more easily than others. Such structure and property measurements of high temperature, highly reactive metallic liquids in both their equilibrium and metastable, supercooled states are made possible through the use of the electrostatic levitation (ESL) technique. Presented here are the results of <italic>in situ</italic> high-energy X-ray scattering studies of metallic liquids and glasses utilizing the Washington University Beamline Electrostatic Levitation (WU-BESL) facility. Structural studies of binary Cu-Zr and Cu-Hf bulk glass-forming liquids and glasses reveal signatures of chemical ordering in the liquid with decreasing temperature and evidence for accelerated ordering in the deeply supercooled state. Novel experimental measurements and Reverse Monte Carlo simulations of the structure of bulk glass-forming Pd₈₂Si₁₈ liquid show a lack of acceleration in ordering, in contrast with the behavior of the widely studied Cu-Zr binary alloy liquids. Measurements of the liquid structures of Si-containing alloys (Au₈₁Si₁₉, Pd₈₂Si₁₈, Ni₇₅Si₂₅, and Pd₇₇Cu₆Si₁₇) reveal a variety of chemical and topological signatures that may provide insight into differences in their glass-forming ability. More specifically, a signature of kinetic strength in structures of the Pd₇₇Cu₆Si₁₇ liquid and glass support previous results while leading to a prediction of the structural behavior of the deeply supercooled Pd₈₂Si₁₈ liquid. In addition, the development of and first results from of a new ESL facility for complimentary neutron diffraction studies for use at the Spallation Neutron Source are also described.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date.available

2014

Author dc:creator

• Vogt, Adam

Contributors dc:contributor

• Kenneth F Kelton

Language dc:language

English (en)

DOI

https://doi.org/10.7936/K7833Q4C

OAI identifier oai:identifier

oai:openscholarship.wustl.edu:etd-2358