In-Situ Sensing using Backscattered Electrons during Electron Beam Powder Bed Fusion Additive Manufacturing

Electron Beam Powder Bed Fusion (EB-PBF) Additive Manufacturing has demonstrated applicability for a variety of materials, including high-temperature refractory metals and crack-prone nickel superalloys, as well as control over local microstructures. However, the benefits of rapid fabrication and microstructural control are overshadowed by long certification times associated with the prediction, measurement, and mitigation of defects at different physical scales. Currently, the foremost technique to qualify EB-PBF parts is post-fabrication volumetric X-ray µCT. However, such efforts are obstructed by strong x-ray attenuation in high-Z AM materials or large parts. As a result, a non-destructive evaluation (NDE) pathway for EB-PBF qualification is presently limited. Therefore, in-situ techniques based on electron interations with materials yield a layer-by-layer spatial distribution of defects have generated significant interest. In this presentation, We will discuss the capabilities and limitations of in-situ backscattered electron data with a highlight on our recent work toward the collection and interpretation ofreal time data.