Georgia Hilburn

Advisors: Naresh Thadhani and Josh Kacher

will propose a doctoral thesis entitled,

Investigating the Effects of Phase Transformation and Loading Conditions on Shock Dissipation and Spall Failure in
 Titanium Alloys

On

Monday, November 23, 2026

12 pm – 2 pm

MRDC 4404

Teams Meeting Link: Georgia Hilburn's Thesis Proposal

Abstract

This work will establish a fundamental understanding of the relationships between initial microstructure, shock-loading history, and martensitic phase transformation, and their effects on shock dissipation and subsequent spall failure in titanium alloys. Plate-impact experiments coupled with time-resolved interferometry and post-mortem characterization will investigate additively manufactured (AM) and wrought metastable β-Ti5553 and dual-phase Ti64 alloys.

Heat treatments of Ti5553 will vary the α-phase fraction, β-phase stability, and phase morphology to assess the contribution of the β → α′′ transformation on shock-wave attenuation across different initial microstructures. The influence of varying microstructures and impact conditions above and below the phase-transformation threshold on wave propagation, tensile loading histories, and damage development will be investigated in Ti5553 alloy. Complementary multi-sample target configurations and wedged-impact experiments on Ti64 will investigate the individual and coupled effects of peak stress, strain rate, and tensile-pulse duration on spall kinetics.

The central hypothesis is that transformation-associated energy dissipation modifies the tensile loading path and can offset the damage-promoting effects of newly formed phase interfaces, producing measurable changes in spall strength and failure mode. Varied impact orientations relative to the AM build direction is expected to influence this competition through its effects on phase transformation and spall damage. Variations in loading history will further govern void nucleation, growth, and coalescence, providing a basis for developing and evaluating kinetic descriptions of damage evolution.

The expected outcome is a mechanistic understanding of how varying microstructures and phase transformation control shock propagation, mitigation, and spall failure. These relationships are necessary for informing physically motivated models of dynamic damage and guide the design of metastable titanium alloys with improved failure resistance.   

Committee:

Prof. Naresh Thadhani - School of Materials Science and Engineering (advisor)

Prof. Josh Kacher - School of Materials Science and Engineering (co-advisor)

Prof. Preet Singh - School of Materials Science and Engineering

Dr. Paul Specht - Sandia National Laboratories

Dr. Kaila Bertsch - Lawrence Livermore National Laboratories