Date of Award

2022-12-01

Degree Name

Doctor of Philosophy

Department

Materials Science And Engineering

Advisor(s)

Stephen W. Stafford

Second Advisor

Darren M. Cone

Abstract

The Ti-6Al-4V alloy is widely used in aerospace applications for its beneficial combination of properties. However, this alloy has high solubility for oxygen and thus a high reactivity. Recovered data contained within the Columbia artifacts suggests that this alloy underwent an accelerated degradation and combustion reaction when exposed to the high enthalpy, low-pressure surroundings experienced during reentry into Earth's atmosphere. Arc-jet testing has provided a simulated aerothermodynamic heating environment to mimic what the spacecraft endured. When the effect of thermal alteration on this alpha-beta phase alloy was investigated during previous studies, optical metallography and microhardness tests revealed inconsistencies between samples from the ground-based model and Ti-6Al-4V remnants from the Columbia shuttle. This study provides a deeper understanding of the mechanisms that govern the material responses. Among other materials characterization methods, Electron Backscatter Diffraction has been recruited to reveal relations between the complex oxidation, ignition, and combustion reactions that occur upon titanium's exposure to this dynamic environment. The research makes use of data gathered during previous research and offers a comparative study involving a portion from the Columbia spacecraft and Ti-6Al-4V plates that were tested using simulated reentry conditions. A more thorough materials characterization provides new insights to help describe the boundaries of what conditions will result in catastrophic failure within the dynamic and extreme environment of reentry.

Language

en

Provenance

Received from ProQuest

File Size

136 p.

File Format

application/pdf

Rights Holder

Arlene Smith

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