TY - JOUR
T1 - Powder-borne porosity in directed energy deposition
AU - Bennett, Jennifer
AU - Webster, Samantha
AU - Byers, John
AU - Johnson, Olivia
AU - Wolff, Sarah
AU - Ehmann, Kornel
AU - Cao, Jian
N1 - Funding Information:
The authors would like to thank Tao Sun and Kamel Fezzaa at Argonne National Laboratory and David Pritchett, Nico Martinez Prieto, Marco Giovannini and Yi Shi at Northwestern University for their assistance with the beamline experiments. This work was supported by the Digital Manufacturing and Design Innovation Institute (DMDII) through award number 15-07 and US Department of Commence National Institute of Standards and Technology's Center for Hierarchical Materials Design (CHiMaD) under grant No. 70NANB19H005 . This work used resources at the Advanced Photon Source, a US Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. This material is also based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1842165 .
Publisher Copyright:
© 2022
PY - 2022/8
Y1 - 2022/8
N2 - Porosity continues to be a concern for the performance of additively manufactured parts. One source of porosity is powder-borne porosity—porosity that is contained in the powder itself. To create a fully dense part, these powder-borne pores need to be released from the melt pool. This study utilizes an in-situ x-ray imaging technique to elucidate the underlying physical phenomena driving the capture or escape of powder-borne pores in directed energy deposition (DED). In total, 80 instances of powder-borne porosity that were captured in the melt pool were identified and tracked. Ultimately, six mechanisms of pore capture and escape were identified. Pore escape was seen to occur via particle melting, pore buoyancy, Marangoni flow, and fluctuation of the liquid-vapor interface, while pore capture was seen to occur via entrainment through particle impact, Marangoni flow, and pore pinning by adjacent particles. Understanding these mechanisms and phenomena is a critical step in enabling the optimization and control of the DED process.
AB - Porosity continues to be a concern for the performance of additively manufactured parts. One source of porosity is powder-borne porosity—porosity that is contained in the powder itself. To create a fully dense part, these powder-borne pores need to be released from the melt pool. This study utilizes an in-situ x-ray imaging technique to elucidate the underlying physical phenomena driving the capture or escape of powder-borne pores in directed energy deposition (DED). In total, 80 instances of powder-borne porosity that were captured in the melt pool were identified and tracked. Ultimately, six mechanisms of pore capture and escape were identified. Pore escape was seen to occur via particle melting, pore buoyancy, Marangoni flow, and fluctuation of the liquid-vapor interface, while pore capture was seen to occur via entrainment through particle impact, Marangoni flow, and pore pinning by adjacent particles. Understanding these mechanisms and phenomena is a critical step in enabling the optimization and control of the DED process.
KW - Directed energy deposition (DED)
KW - In-situ X-ray imaging
KW - Pore elimination
KW - Pore formulation
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U2 - 10.1016/j.jmapro.2022.04.036
DO - 10.1016/j.jmapro.2022.04.036
M3 - Article
AN - SCOPUS:85131719957
SN - 1526-6125
VL - 80
SP - 69
EP - 74
JO - Journal of Manufacturing Processes
JF - Journal of Manufacturing Processes
ER -