All ETDs from UAB

Advisory Committee Chair

Yogesh K Vohra

Advisory Committee Members

Shane A Catledge

Andrew A Wereszczak

Rostislav Hrubiak

Cheng-Chien Chen

Document Type

Dissertation

Date of Award

2019

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

Multi-angle energy-dispersive X-ray diffraction (EDXD) and white-beam radiography studies were conducted on a borosilicate glass sample (17.6% B2O3) to 13.7 GPa in a Paris-Edinburgh (PE) press at Beamline 16-BM-B, HPCAT, The Advanced Photon Source, Argonne National Laboratory. The measured structure factor S(q) to q = 19 Å-1 was used to determine internuclear bond distances between various species of atoms contained in the glass sample. Bond distances for Si-O, O-O, and Si-Si were determined from the reduced pair distribution function G(r) and were measured as a function of pressure. The sample height, as determined via white-beam radiography, showed an overall uniaxial compression of 22.5% at 13.7 GPa and a 10.6% permanent compaction after decompression to ambient conditions. Raman spectroscopy of the pressure recovered borosilicate glass sample as compared to the bulk starting material shows blue-shift and changes in intensities and widths of the Raman bands associated with four-coordinated boron and silicate rings. Density measurements of borosilicate glasses of varying B2O3 percentages revealed that a higher B2O3 percentage leads to a greater volume change after compression to ~12 GPa. A high pressure, high temperature study on Vit 106a bulk metallic glass reveals a large volume collapse at 460°C via X-ray radiography, which is indicative of crystallization. There are five equilibrium crystalline phases for the fully crystallized sample at 800°C: ZrCu, Zr2Cu, Zr3Al2, Zr4Al3, and Zr2Ni. The effect of pressure and heating rate on crystallization temperature was investigated for Vit 106a. Three different heating rates were studied: 1.2°C/min, 2.4°C/min, and 6.0°C/min. A trend is seen where an increase in heating rate leads to an increase in crystallization temperature, and for each heating rate there is a positive correlation between pressure and crystallization temperature in a low-pressure range from ambient to ~3-4 GPa, and a negative correlation between pressure and crystallization temperature in a range from 3-4 GPa – 6.5 GPa.

Share

COinS