Additive Manufacturing of Multicomponent Metal Alloys

Throughout history, metallurgists have altered the properties and compositions of alloys to achieve higher performance materials. Over time the demand for better performing materials has led to increasingly complex alloys. This trend has peaked in the past 20 years with the introduction of multicomponent and high entropy alloys (HEA). Unlike traditional alloys, HEAs do not contain a single primary element; instead, all the elements in the alloy are mixed in relatively (almost equiatomic) concentrations. In addition to a vast design space, multicomponent and high entropy alloys offer many advantages due to their high configurational entropy such as improved hardness and strength. Despite the great potential that HEAs present for researchers to explore vast design spaces, they can be very difficult to process via conventional due to their high viscosity, sluggish diffusion, and considerable solidification shrinkage, which can easily lead to casting defects. Additive manufacturing is one method that can be used to address these challenges and produce defect-free HEAs with interesting microstructures and mechanical properties. Additive manufacturing (AM) is a popular technology that produces geometrically complicated parts with tight tolerances and low initial investment. AM of alloys can involve numerous techniques such as laser powder bed fusion (L-PBF), direct energy deposition (L-DED), wire/plasma arc additive manufacturing (W/PAAM), direct ink writing (DIW). These techniques require careful control to mitigate printing defects and control the microstructure and phase formation within multicomponent alloys. While AM provides a unique opportunity to process multicomponent alloy systems, these techniques are still relatively new and must be systematically studied to optimize their output. This work will focus on additive manufacturing of multicomponent alloy systems produced by L-PBF, L-DED, DIW, and PAAM to explore the effects of processing conditions on defects, microstructure, and phases in these printed materials. The impact of these features on the mechanical properties of the materials will also be explored at a fundamental level to understand the corresponding deformation mechanisms present in these exotic materials manufactured under the unique processing conditions in AM. This work will also cover a systematic study of the processing conditions employed under each AM method and how they can be optimized to control the defects and thermal history to produce defect-free parts with high mechanical performance