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Instruments / Technical Area	Publication Details	Published
I12-JEEP: Joint Engineering, Environmental and Processing	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 Fenech , Thomas Connolley , Robert C. Atwood , Oxana V. Magdysyuk , Gavin J. Baxter , Martyn A. Jones , Chu Lun Alex Leung , Peter D. Lee Acta Materialia 21 DOI: 10.1016/j.actamat.2021.116777 Diamond Proposal Number(s): [20096] Show Abstract ▼ 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 µm. 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.	Mar 2021
I12-JEEP: Joint Engineering, Environmental and Processing	Synchrotron X-ray imaging of directed energy deposition additive manufacturing of titanium alloy Ti-6242 Yunhui Chen , Samuel J. Clark , Lorna Sinclair , Chu Lun Alex Leung , Sebastian Marussi , Thomas Connolley , Robert C. Atwood , Gavin J. Baxter , Martyn A. Jones , Iain Todd , Peter D. Lee Additive Manufacturing 92 DOI: 10.1016/j.addma.2021.101969 Diamond Proposal Number(s): [20096] Show Abstract ▼ Abstract: Directed Energy Deposition Additive Manufacturing (DED-AM) is transformative for the production of larger, geometrically complex metallic components. However, the mechanical properties of titanium alloy DED-AM components do not always reach their full potential due to microstructural features including porosity and regions of lack of fusion. Using in situ and operando synchrotron X-ray imaging we gain insights into key laser-matter interaction and microstructural feature formation mechanisms during DED-AM of Ti-6242. Analysis of the process conditions reveals that laser power is dominant for build efficiency while higher traverse speed can effectively reduce lack of fusion regions. We also elucidate the mechanisms underlying several physical phenomena occurring during the deposition of titanium alloys, including the formation of a saddle-shaped melt pool and pore pushing. The findings of this work clarify the transient kinetics behind the DED-AM of titanium alloys and can be used as a guide for optimising industrial additive manufacturing processes.	Mar 2021
E01-JEM ARM 200CF	Evaluation and realization of safer Mg-S battery: the decisive role of the electrolyte Lin Sheng , Zhangxiang Hao , Junrun Feng , Wenjia Du , Manxi Gong , Liqun Kang , Paul R. Shearing , Dan J. I. Brett , Yunhui Huang , Feng Ryan Wang Nano Energy 334 DOI: 10.1016/j.nanoen.2021.105832 Diamond Proposal Number(s): [20643] Show Abstract ▼ Abstract: The magnesium–sulfur (Mg-S) battery may be a safer alternative for the lithium-sulfur battery because Mg plating usually proceeds without dendrite formation. Here, we correlate the thermal runaway of Mg-S battery with the associated change of electrolyte vapour pressure via battery testing calorimetery. Over-pressure builds up along with the programmed heating of the cell, and as a result, the thermal runaway is triggered at 20 to 45 K over the electrolyte boiling point, corresponding to 70 to 150 kPa pressure difference between the cell and the environment. The distinct performance-safety-cost behaviours of three ether type of electrolytes stems from the different CH2CH2O chain lengths. Such molecular insight will serve as a fundamental guideline in choosing and designing the desired electrolyte that simultaneously achieves a high explosion limit and good electrochemical performance.	Jan 2021
I12-JEEP: Joint Engineering, Environmental and Processing	In situ X-ray quantification of melt pool behaviour during directed energy deposition additive manufacturing of stainless steel Yunhui Chen , Samuel J. Clark , Yuze Huang , Lorna Sinclair , Chu Lun Alex Leung , Sebastian Marussi , Thomas Connolley , Oxana V. Magdysyuk , Robert C. Atwood , Gavin J. Baxter , Martyn A. Jones , Iain Todd , Peter D. Lee Materials Letters DOI: 10.1016/j.matlet.2020.129205 Diamond Proposal Number(s): [20096] Open Access Show Abstract ▼ Abstract: The Directed Energy Deposition Additive Manufacturing (DED-AM) of SS316L was studied using in situ and operando synchrotron X-ray imaging to quantitively understand the effect of processing parameters on the melt-pool morphology and surface quality. It was found that surface roughness of DED-AM builds can result from melt pool surface perturbations caused by changes in the melt flow and build stage motion perturbations. Process maps are developed that quantitatively correlate build quality to process parameters including powder feed rate, laser power and traverse speed. How the AM process parameters control build efficacy is clarified, and the processing conditions required to dampen surface perturbations leading to roughness were determined.	Dec 2020
I12-JEEP: Joint Engineering, Environmental and Processing	Melt pool morphology in directed energy deposition additive manufacturing process Y. Chen , S. Clark , A. C. L. Leung , L. Sinclair , S. Marussi , R. Atwood , T. Connolley , M. Jones , G. Baxter , Peter Lee Iop Conference Series: Materials Science And Engineering 861 MCWASP XV 2020 DOI: 10.1088/1757-899X/861/1/012012 Diamond Proposal Number(s): [20096] Open Access Show Abstract ▼ Abstract: Directed Energy Deposition Additive Manufacturing (DED-AM) is one of the principal AM techniques being explored for both the repair of high value components in the aerospace industry as well as freeform fabrication of large metallic components. However, the lack of fundamental understanding of the underlying process-structure-property relationships hinders the utilisation of DED-AM for the production or repair of safety-critical components. This study uses in situ and operando synchrotron X-ray imaging to provide an improved fundamental understanding of laser-matter interactions and their influence on the melt pool geometry. Coupled with process modelling, these unique observations illustrate how process parameters can influence the DED-AM melt pool geometry. The calibrated simulation can be used for guidance in an industrial additive manufacturing process for microstructure and quality control.	May 2020

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