Correlative Synchrotron X-ray Imaging and Diffraction of Directed Energy Deposition Additive Manufacturing

Yunhui Chen*, Samuel J. Clark, David M. Collins*, Sebastian Marussi, Simon A. Hunt, Danielle M. Fenech, Thomas Connolley, Robert C. Atwood, Oxana V. Magdysyuk, Gavin J. Baxter, Martyn A. Jones, Chu Lun Alex Leung, Peter D. Lee*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

The governing mechanistic behaviour of Directed Energy Deposition Additive Manufacturing (DED-AM) is revealed by a combined in situ and operando synchrotron X-ray imaging and diffraction study of a nickel-base superalloy, IN718. Using a unique DED-AM process replicator, real-space imaging enables quantification of the melt-pool boundary and flow dynamics during solidification. This imaging knowledge was also used to inform precise diffraction measurements of temporally resolved microstructural phases during transformation and stress development with a spatial resolution of 100 µm. The diffraction quantified thermal gradient enabled a dendritic solidification microstructure to be predicted and coupled to the stress state. The fast cooling rate entirely suppressed the formation of secondary phases or recrystallisation in the solid-state. Upon solidification, the stresses rapidly increase to the yield strength during cooling. This insight, combined with the large solidification range of IN718 suggests that the accumulated plasticity exhausts the ductility of the alloy, causing liquation cracking. This study has revealed the mechanisms that govern the formation of highly non-equilibrium microstructures during DED-AM.

Original languageEnglish
Article number116777
Number of pages13
JournalActa Materialia
Volume209
Early online date1 Mar 2021
DOIs
Publication statusPublished - 1 May 2021

Bibliographical note

Acknowledgements:
This research was supported under MAPP: EPSRC Future Manufacturing Hub in Manufacture using Advanced Powder Processes (EP/P006566/1), a Royal Academy of Engineering Chair in Emerging Technology (CiET1819/10), and Rolls-Royce plc. via the Horizon 2020 Clean Sky 2 WP5.8.1 programme. This work has been supported by the Office of Naval Research (ONR) Grant N62909-19-1-2109. The provision of materials and technical support from Rolls-Royce plc is gratefully acknowledged. Laboratory space and facilities were provided by the Research Complex at Harwell. The authors thank Diamond Light Source for providing beamtime (MT20096) and the staff at I12 beamline for technical assistance.

Publisher Copyright:
© 2021

Keywords

  • Directed Energy Deposition Additive Manufacturing
  • IN718
  • Laser Additive Manufacturing
  • Synchrotron X-ray diffraction
  • Synchrotron X-ray imaging

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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