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In situ X-ray imaging of defect and molten pool dynamics in laser additive manufacturing

DOI: 10.1038/s41467-018-03734-7 DOI Help

Authors: Chu Lun Alex Leung (The University of Manchester) , Sebastian Marussi (The University of Manchester) , Robert C. Atwood (Diamond Light Source) , Michael Towrie (Research Complex at Harwell) , Philip J. Withers (The University of Manchester) , Peter D. Lee (University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Communications , VOL 9

State: Published (Approved)
Published: April 2018
Diamond Proposal Number(s): 11761

Open Access Open Access

Abstract: The laser–matter interaction and solidification phenomena associated with laser additive manufacturing (LAM) remain unclear, slowing its process development and optimisation. Here, through in situ and operando high-speed synchrotron X-ray imaging, we reveal the underlying physical phenomena during the deposition of the first and second layer melt tracks. We show that the laser-induced gas/vapour jet promotes the formation of melt tracks and denuded zones via spattering (at a velocity of 1 m s−1). We also uncover mechanisms of pore migration by Marangoni-driven flow (recirculating at a velocity of 0.4 m s−1), pore dissolution and dispersion by laser re-melting. We develop a mechanism map for predicting the evolution of melt features, changes in melt track morphology from a continuous hemi-cylindrical track to disconnected beads with decreasing linear energy density and improved molten pool wetting with increasing laser power. Our results clarify aspects of the physics behind LAM, which are critical for its development.

Journal Keywords: Design, synthesis and processing; Imaging techniques; Metals and alloys

Subject Areas: Materials

Instruments: I12-JEEP: Joint Engineering, Environmental and Processing


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