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Zhang K, Chen Y, Marussi S, Fan X, Fitzpatrick M, Bhagavath S, Majkut M, Lukic B, Jakata K, Rack A, Jones MA, Shinjo J, Panwisawas C, Leung CLA, Lee PD. Pore evolution mechanisms during directed energy deposition additive manufacturing. Nat Commun 2024; 15:1715. [PMID: 38402279 PMCID: PMC10894260 DOI: 10.1038/s41467-024-45913-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 02/06/2024] [Indexed: 02/26/2024] Open
Abstract
Porosity in directed energy deposition (DED) deteriorates mechanical performances of components, limiting safety-critical applications. However, how pores arise and evolve in DED remains unclear. Here, we reveal pore evolution mechanisms during DED using in situ X-ray imaging and multi-physics modelling. We quantify five mechanisms contributing to pore formation, migration, pushing, growth, removal and entrapment: (i) bubbles from gas atomised powder enter the melt pool, and then migrate circularly or laterally; (ii) small bubbles can escape from the pool surface, or coalesce into larger bubbles, or be entrapped by solidification fronts; (iii) larger coalesced bubbles can remain in the pool for long periods, pushed by the solid/liquid interface; (iv) Marangoni surface shear flow overcomes buoyancy, keeping larger bubbles from popping out; and (v) once large bubbles reach critical sizes they escape from the pool surface or are trapped in DED tracks. These mechanisms can guide the development of pore minimisation strategies.
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Affiliation(s)
- Kai Zhang
- Department of Mechanical Engineering, University College London, London, WC1E 7JE, UK.
- Research Complex at Harwell, Harwell Campus, Didcot, OX11 0FA, UK.
| | - Yunhui Chen
- Department of Mechanical Engineering, University College London, London, WC1E 7JE, UK
- Research Complex at Harwell, Harwell Campus, Didcot, OX11 0FA, UK
- ESRF-The European Synchrotron, 38000, Grenoble, France
- School of Engineering, RMIT University, Melbourne, VIC, 3000, Australia
| | - Sebastian Marussi
- Department of Mechanical Engineering, University College London, London, WC1E 7JE, UK
- Research Complex at Harwell, Harwell Campus, Didcot, OX11 0FA, UK
| | - Xianqiang Fan
- Department of Mechanical Engineering, University College London, London, WC1E 7JE, UK
- Research Complex at Harwell, Harwell Campus, Didcot, OX11 0FA, UK
| | - Maureen Fitzpatrick
- Department of Mechanical Engineering, University College London, London, WC1E 7JE, UK
- ESRF-The European Synchrotron, 38000, Grenoble, France
| | - Shishira Bhagavath
- Department of Mechanical Engineering, University College London, London, WC1E 7JE, UK
- Research Complex at Harwell, Harwell Campus, Didcot, OX11 0FA, UK
| | - Marta Majkut
- ESRF-The European Synchrotron, 38000, Grenoble, France
| | | | - Kudakwashe Jakata
- ESRF-The European Synchrotron, 38000, Grenoble, France
- Diamond Light Source, Harwell Campus, Oxfordshire, OX11 0DE, UK
| | | | | | - Junji Shinjo
- Next Generation Tatara Co-Creation Centre, Shimane University, Matsue, 690-8504, Japan
| | - Chinnapat Panwisawas
- School of Engineering and Materials Science, Queen Mary University of London, London, E1 4NS, UK
| | - Chu Lun Alex Leung
- Department of Mechanical Engineering, University College London, London, WC1E 7JE, UK
- Research Complex at Harwell, Harwell Campus, Didcot, OX11 0FA, UK
| | - Peter D Lee
- Department of Mechanical Engineering, University College London, London, WC1E 7JE, UK.
- Research Complex at Harwell, Harwell Campus, Didcot, OX11 0FA, UK.
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