Melt-Pool Dynamics and Microstructure of Mg Alloy WE43 under Laser Powder Bed Fusion Additive Manufacturing Conditions

Content Provider	Directory of Open Access Journals (DOAJ)
Author	Julie Soderlind Aiden A. Martin Nicholas P. Calta Philip J. DePond Jenny Wang Bey Vrancken Robin E. Schäublin Indranil Basu Vivek Thampy Anthony Y. Fong Andrew M. Kiss Joel M. Berry Aurélien Perron Johanna Nelson Weker Kevin H. Stone Christopher J. Tassone Michael F. Toney Anthony Van Buuren Jörg F. Löffler Subhash H. Risbud Manyalibo J. Matthews
Abstract	Magnesium-based alloy WE43 is a state-of-the-art bioresorbable metallic implant material. There is a need for implants with both complex geometries to match the mechanical properties of bone and refined microstructure for controlled resorption. Additive manufacturing (AM) using laser powder bed fusion (LPBF) presents a viable fabrication method for implant applications, as it offers near-net-shape geometrical control, allows for geometry customization based on an individual patient, and fast cooling rates to achieve a refined microstructure. In this study, the laser–alloy interaction is investigated over a range of LPBF-relevant processing conditions to reveal melt-pool dynamics, pore formation, and the microstructure of laser-melted WE43. In situ X-ray imaging reveals distinct laser-induced vapor depression morphology regimes, with minimal pore formation at laser-scan speeds greater than 500 mm/s. Optical and electron microscopy of cross-sectioned laser tracks reveal three distinct microstructural regimes that can be controlled by adjusting laser-scan parameters: columnar, dendritic, and banded microstructures. These regimes are consistent with those predicted by the analytic solidification theory for conduction-mode welding, but not for keyhole-mode tracks. The results provide insight into the fundamental laser–material interactions of the WE43 alloy under AM-processing conditions and are critical for the successful implementation of LPBF-produced WE43 parts in biomedical applications.
e-ISSN	20734352
DOI	10.3390/cryst12101437
Journal	Crystals
Issue Number	10
Volume Number	12
Language	English
Publisher	MDPI AG
Publisher Date	2022-01-01
Publisher Place	Switzerland
Access Restriction	Open
Subject Keyword	Crystallography Additive Manufacturing Magnesium Laser Powder Bed Fusion X-ray Imaging Electron Microscopy Microstructure
Content Type	Text
Resource Type	Article