Author's School

Graduate School of Arts & Sciences

Author's Department/Program

Physics

Language

English (en)

Date of Award

Summer 9-1-2014

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Chair and Committee

Kenneth F Kelton

Abstract

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 in situ 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.

Comments

This work is not available online per the author’s request. For access information, please contact digital@wumail.wustl.edu or visit http://digital.wustl.edu/publish/etd-search.html.

Permanent URL: http://dx.doi.org/10.7936/K7833Q4C

Download

Share

COinS