Alex Butler
Advisor: Prof. Aaron Stebner and Prof. Josh Kacher

will propose a doctoral thesis entitled,

The Process-Structure-Property Relationship of Aluminum Metal Matrix Composites Reinforced via Reactive Additive Manufacturing

On

Tuesday, December 9th at 2:00 pm

In 

J. Erskine Love Jr. Manufacturing room 299

And 

Zoom Link:

https://gatech.zoom.us/meetings/91380402841/invitations?signature=RjTjl_x3-TB-A5b0XR4fKSMwQFq_ptdgJV62Aup4z9w

Meeting ID: 913 8040 2841

Passcode: 352794

Committee
            Prof. Aaron Stebner– School of Mechanical Engineering (advisor)
            Prof. Josh Kacher– School of Materials Science & Engineering (advisor)
            Prof. Naresh Thadhani – School of Materials Science & Engineering
            Prof. Rick Neu – School of Mechanical Engineering 

      Dr. Ashely Spear- University of Utah, School of Mechanical Engineering

Abstract
Aluminum alloys have various applications in aerospace, automotive, and ground based military craft due to their high strength to weight ratio, ductility, low density, and low cost. Laser powder bed fusion (PBF-LB) is an additive manufacturing technique that allows for these parts to be fabricated with more complex geometries than traditional casting methods. However, aluminum is very difficult to additively manufacture in this manner due to its wide solidification range, high thermal conductivity, and high laser reflectively producing a part with cracks and columnar grains. Inoculation is one method to improve the printability of aluminum through the nucleation of finer grain sizes. Reactive additive manufacturing (RAM) forms the inoculants in situ during laser powder bed fusion through chemical reactions between the starting powders. Here, we mix titanium and boron carbide powders with A1000 powders to form aluminum reinforced with TiB2 and TiC following laser powder bed fusion. The addition of these particles has been shown to improve the strength of aluminum alloys and refine the microstructure, but the reaction process has also been shown to not be fully carried out following PBF-LB leaving a variety of coarse particles and precipitates distributed throughout the aluminum matrix. In the first part of this thesis, I will reveal the mechanisms by which the addition of these particles enhances the ductility along with the strength using a combination of mechanical testing, electron microscopy, and statistical analysis. In the second part, I will produce statistical metrics for understanding the contribution of the partially reacted titanium particles to the fracture behavior. In the third part, I will construct a method for the reaction process in our material to complete with an understanding of the underlying thermodynamics followed by an analysis of the mechanical properties. Implications of this work will include informing the manufacturing and material design of aluminum metal matrix composites through a fundamental understanding on the structure-property effects of in situ formed particle reinforcements