Date of Award

Summer 8-2-2024

Degree Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Materials Science

Committee Chair

Jerome Downey

Abstract

Metallic glasses are metal-based alloys that have an amorphous structure and glass transition behavior as a result of being cooled rapidly enough to suppress crystal nucleation and growth[1]. Metallic glasses have been formed with two to eight constituents[2][3][4]; however, the most stable glass-forming systems typically contain four or more elements. With few exceptions, metallic glass-forming alloys are extremely unstable, requiring cooling rates on the order of 108-10-2 K/s to form a glassy sample. This instability translates to reheating, where onset crystallization temperatures infrequently exceed the glass transition by more than 100K. Strong glass-forming ability typically occurs over a narrow composition range, resulting in high-purity constituents (99.9% or higher) being required for synthesis. The amorphous structures observed in these materials lack the defects and mechanisms associated with crystalline metals. Instead, the non-crystalline structures give rise to a multitude of unique properties that differentiate glassy alloys from their crystalline counterparts. Desirable properties include high-strength [5][6], corrosion resistance [7][8], wear resistance [9][10], and high elastic resilience [11][12] in comparison to crystalline metals. These promising material properties qualify metallic glasses (MGs) for applications in aerospace, biomaterials, magnetic materials, and catalysts[13][14]. The stability of any metallic glass is sensitive to chemistry, temperature, processing environment, and contamination during processing. As a result, a significant research effort has been directed toward investigating the stability of a variety of possible glass-forming systems and glass-processing methods. Many promising properties and elusive stability have made MGs the focus of a significant amount of research since their discovery in the 1960s[15].

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