Advisor(s)
Shane Catledge
Committee Member(s)
Gayan Wijeratne
Manoj Mahapatra
Wenli Bi
Yogesh Vohra
School
College of Arts and Sciences
Document Type
Dissertation
Department (new version)
Physics
Date of Award
1-7-2025
Abstract
This dissertation presents the novel approach for synthesizing high entropy borides (HEBs) and high entropy alloys (HEAs) using microwave-induced plasma as a rapid and efficient processing tool. High entropy materials (HEMs) have peaked interested in recent years due to their unique properties and practical applications such as thermal stability, and corrosion and wear resistance. HEMs are designed by combining multiple principal elements in near-equimolar ratios, enhancing stability, and offering a broad spectrum of tailored mechanical properties. The inclusion of multiple transition metals within these structures increases hardness and oxidation resistance, and the flexibility in element selection enables precise tuning for specific applications, such as high-speed machining or high-temperature structural components. This work employs advanced synthesis methods, including microwave plasma and metal oxide reduction, to fabricate these materials under controlled conditions, ensuring uniform elemental distribution and optimized microstructures. By studying the formation mechanisms within these non-equilibrium environments, this research aims to optimize the performance of high-entropy materials. HEBs synthesized through microwave plasma demonstrated superior hardness and oxidation resistance compared to traditional diborides, as confirmed by Vickers and nanoindentation tests, showing significantly higher values than those reported for similar compositions produced by alternative methods. The dissertation also explores the effects of reactive versus inert plasma environments, focusing on the use of hydrogen as a feedgas. The results reveal that a reactive hydrogen environment promotes the formation of hexagonal AlB2-type HEB structures at lower temperatures compared to an argon environment. The dissociation of molecular hydrogen into atomic hydrogen enables efficient reduction of metal oxide precursors, facilitating synthesis without melting—an advantage over conventional methods. This work highlights multiple pathways for HEM synthesis (boro/ Boro carbothermal and metal oxide reduction) and evaluates their structural and mechanical properties, providing insights into the optimization of high-entropy materials using microwave plasma.
ProQuest ID
Recommended Citation
Storr, Bria Christina, "New Frontiers In Synthesis Of High-Entropy Materials Enabled By Microwave-Induced Plasma" (2025). All ETDs from UAB. 7284.
https://digitalcommons.library.uab.edu/etd-collection/7284
