Ultrasonic Measurements of the Elastic Properties of Lanthanum/Cerium-based Bulk Metallic Glass and its Compression Behavior under High Pressure

Authors

Xintong Qi

Type

Text

Type

Thesis

Advisor

Welch, David | Li, Baosheng | Gersappe, Dilip.

Date

2014-12-01

Keywords

Materials Science | Cerium, high pressure, metallic glass

Department

Department of Materials Science and Engineering.

Language

en_US

Source

This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.

Identifier

http://hdl.handle.net/11401/76339

Publisher

The Graduate School, Stony Brook University: Stony Brook, NY.

Format

application/pdf

Abstract

Metallic glass, as a new member of glass family, has been at the cutting edge of material research for decades since it was first discovered in 1960. Its amorphous, densely packed microstructure makes it popular not only in industrial applications, but also in condensed matter physics. The elastic properties and their pressure dependence provide critical information about the bonding characteristics, microstructure and vibration features of metallic glasses. In this thesis, for the first time, the elastic wave velocities of (La_0.5Ce_0.5)₆₄Al₁₆Ni₅Cu₁₅ bulk metallic glass are measured under high pressure up to 12.3 GPa using ultrasonic interferometry within a multi-anvil apparatus at room temperature. Analysis of acoustic and P-V data allows a direct determination of the elastic moduli such as the bulk modulus K, shear modulus G, Young's modulus E, and Poisson's ratio &nu. Both longitudinal and shear modes exhibit softening behavior under low pressure similar to that of typical oxide glasses. This implies that Ce-based bulk metallic glass contains short-range covalent-like bonds. At higher pressure, discontinuities in bulk and shear moduli are observed at 5.9 GPa. The Debye temperature and Vickers hardness are also investigated to further understanding of its mechanical properties. All these results enable us to gain insight into the high pressure behavior and physical properties of bulk metallic glass, and also to further our understanding of the polyamorphism in Ce-based metallic glasses. | 51 pages

Recommended Citation

Qi, Xintong, "Ultrasonic Measurements of the Elastic Properties of Lanthanum/Cerium-based Bulk Metallic Glass and its Compression Behavior under High Pressure" (2014). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 2263.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/2263