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Correlative synchrotron X-ray imaging and diffraction of directed energy deposition additive manufacturing

DOI: 10.1016/j.actamat.2021.116777 DOI Help

Authors: Yunhui Chen (University College London; Research Complex at Harwel) , Samuel J. Clark (University College London; Research Complex at Harwell) , David M. Collins (University of Birmingham) , Sebastian Marussi (University College London; Research Complex at Harwell) , Simon A. Hunt (University of Manchester) , Danielle Fenech (University of Cambridge) , Thomas Connolley (Diamond Light Source) , Robert C. Atwood (Diamond Light Source) , Oxana V. Magdysyuk (Diamond Light Source) , Gavin J. Baxter (Rolls-Royce plc) , Martyn A. Jones (Rolls-Royce plc) , Chu Lun Alex Leung (University College London; Research Complex at Harwell) , Peter D. Lee (University of Manchester; Research Complex at Harwell)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Acta Materialia , VOL 21

State: Published (Approved)
Published: March 2021
Diamond Proposal Number(s): 20096

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 DAE-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 informed precise diffraction measurements of temporally resolved microstructural phases during transformation and stress development with a spatial resolution of 100 ┬Ám. The diffraction quantified thermal gradient enabled a dendritic solidification microstructure to be predicted and coupled to the stress orientation and magnitude. 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 additional fundamental mechanisms governing the formation of highly non-equilibrium microstructures during DED-AM.

Journal Keywords: Directed Energy Deposition Additive Manufacturing; Synchrotron X-ray diffraction; Synchrotron X-ray imaging; Laser Additive Manufacturing; IN718

Subject Areas: Materials

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

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