Alex Butler

Advisors: Josh Kacher and Aaron Stebner

will defend a doctoral thesis entitled,

Influence of Heterogeneous Particulate Reinforcements on Deformation and Damage in Aluminum Composites Formed by Reactive Additive Manufacturing

On

Thursday, November 12, 2026

12 pm – 2 pm

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or virtually via Teams:

Join: https://teams.microsoft.com/meet/248266455555984?p=93WUJ1utqZm4Pd8eD9

Meeting ID: 248 266 455 555 984

                                                                                            Passcode: zZ9Kw7aL

Committee:

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

Prof. Aaron Stebner - School of Materials Science and Engineering (co-advisor)

Prof. Naresh Thadhani - School of Materials Science and Engineering

Prof. Richard Neu - Woodruff School of Mechanical Engineering

Prof. Ashley Spear - Department of Mechanical Engineering, University of Utah

Abstract

   Laser powder bed fusion (PBF-LB) enables the fabrication of complex parts, but aluminum alloys manufactured through this process remain susceptible to solidification cracking and anisotropic mechanical properties associated with columnar grain growth. Reactive additive manufacturing (RAM) is a method of promoting grain refinement and introducing reinforcement particles through in situ chemical reactions between reactive powder constituents during processing. However, incomplete reactions contribute to heterogeneous microstructures containing variations in particle size, shape, composition, and spatial distribution, which can influence deformation and fracture behavior. Understanding these effects is important for identifying potential damage initiation mechanisms and their effect on tensile properties. In this work, I investigated the relationships between heterogeneous reinforcement particles, deformation and fracture, and mechanical properties in Al-Ti-B₄C composites formed through RAM.

First, in situ scanning electron microscopy (SEM) tensile testing was coupled with digital image correlation (DIC) to analyze local strain distributions as they relate to the reinforcement particles over different volume fractions. Machine learning approaches were then employed to quantify the relative importance of particle geometry and composition in predicting particle crack initiation and propagation under uniaxial tension. Finally, the laser-material interaction time during PBF-LB was progressively increased to study the influence of increasing thermal exposure on the progression of the in situ chemical reactions, porosity, and subsequent tensile properties. These studies provide a foundation for the microstructural considerations necessary in developing PBF-LB processing strategies that balance the benefits of in situ reinforcement particle formation against the introduction of features which may compromise tensile performance.