Title: Processing of Nanoscale Lamellae in Bulk Al-Cu Eutectic Samples Through Selective Laser Melting
Abstract: Eutectic alloys are currently used in a variety of industries, from high strength casting alloys to wafer bonding in electronics, and have potential applications in thermoelectrics, biomimicry, and metamaterials. These technologies utilize the high density of interfaces found in this two-phase system and are thus all positioned to take advantage of a processing technique that can drive this microstructure down to the nanoscale in bulk material. Selective laser melting (SLM), a form of additive manufacturing, is shown in this research to have the ability to produce bulk materials with nanostructured lamellar eutectic. The Al-Cu system is studied here as a model eutectic, laying the ground work for other eutectic systems that may have more relevance within various technologies. The research proposed here aims to investigate the ability to control both the dimensions and direction of the eutectic microstructure within a bulk material through careful selection of processing parameters and scan strategies during SLM processing. Through this, the potential to create hierarchical structures that mimic those found in nature will be developed, with attention paid to the changes that these structures have on the mechanical properties of the material. To facilitate this research and potential future investigations into other eutectic systems, improvements to in situ alloying of elemental powder during SLM are proposed, focusing on the effects powder size and remelting strategies have on the homogeneity of the produced microstructure. Lastly, a study into the growth of the eutectic microstructure from the melt pool boundaries within the material is proposed, where the registry between lamellae and colonies across the interfaces is investigated.
James Howe, MSE, Chair
James Fitz-Gerald, MSE, Adviser
Jerald Floro, MSE, Adviser
Ji Ma, MSE
Leonid Zhigilei, MSE
Xiaodong (Chris) Li, MAE