"Functionally Integrated Materials via Additive Manufacturing: Micro-mechanical Testing, In-situ Imaging, and Alternative Feedstock Materials"
This presentation will provide an overview of various aspects of metal additive manufacturing that can lead to transformative materials and engineering design. Directed energy deposition (DED) additive manufacturing enables the precise control of composition for the development of functionally integrated materials (FIMs) with site-specific functionality. This compositional control is enabled by the powder injection delivery system that allows for the sequential and / or co-deposition of multiple feedstock powders through individual powder feeders. This strategy provides a path to the rapid development of novel alloys and components with location-dependent chemical composition and properties. The FIMs concept is demonstrated using two material systems: stainless steel 316L with Haynes 282 nickel superalloy, and nickel with nickel-aluminum. Extensive characterization of microstructure, interfaces, diffusion zones, grain boundary morphology and texture, chemical composition and phase transformations provides insight into the fundamental materials science governing the solidification process and consequential component performance in FIMs. Micro-mechanical testing affirms the variations in behavior that are derived from this compositional control. DED also entails complex particle-laser-melt pool interactions due to the powder injection mechanism. In-situ imaging using both thermal imaging and high-speed video provides insight into these complex interactions, as highlighted here for various material systems. Lastly, the benefits of using coated powders, and recycled or repurposed alternative feedstock materials are considered.
