Abstract
Electron beam melting (EBM) is an additive manufacturing technology that can process materials and manufacture components otherwise impossible or uneconomical. However, defects, including porosity and surface irregularities, are widely reported in EBM-built components, and their formation mechanisms are not fully understood. Here, using in-situ high-speed synchrotron X-ray imaging, we reveal that bubble explosions in Al6061 during EBM induce melt pool instabilities contributing to defect formation. The melt pool and keyhole evolve through three stages: (1) initial formation of a melt pool, (2) subsurface bubble formation and explosion, and (3) periodic keyhole oscillation. During scanning, periodic bubble explosions can eject molten liquid as spatters and disturb the vapor depression and melt pool, contributing to surface humping, that may trigger lack-of-fusion defects in subsequent layers. The physical insights we report could provide guidance for EBM machine development, process innovation, alloy design and model development.
Data availability
The authors declare that the data supporting the findings of this study are available within the paper and its supplementary information files Source data are provided with this paper.
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Acknowledgments
This work is supported by Vilas Associate Award (L.C.) and the U.S. Department of Commerce (Award ID number: 70NANB21H039, L.C.). This research used resources of the Advanced Photon Source, a U.S. 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. The authors would like to thank Drs. Fan Zhang, Lyle Levine, Brandon Lane, Brian Simonds, and Nik Hrabe from the National Institute of Standards and Technology (NIST) for fruitful discussions. The authors appreciate Drs. Scott Sanders, Matthias Beuting, Brandon Walker and Kevin Eliceiri at the University of Wisconsin-Madison for their helpful suggestions.
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L.C. and J.Y. conceived the idea. L.C. supervised the research project. J.Y. and L.C. designed the experiment. L.I.E. S.J.C., K.F., J.Y., J.H., A.N., Q.L., and L.C. conducted the X-ray imaging experiments. J.Y. performed the data analysis and characterization. J.Y. and L.C. wrote the paper with input from all authors. All authors discussed the results and reviewed the manuscript.
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Nature Communications thanks Feng Lin, Nick Semjatov, and the other anonymous reviewer(s) for their contribution to the peer review of this work. A peer review file is available.
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Yuan, J., Escano, L.I., Clark, S.J. et al. Bubble explosion induced melt pool instabilities in electron beam melting of aluminum alloy. Nat Commun (2026). https://doi.org/10.1038/s41467-026-71118-3
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DOI: https://doi.org/10.1038/s41467-026-71118-3
