@article{5bfd307b08c44b1e8b01293317d3a9d1,
title = "Kinetics of alloy formation and densification in Fe-Ni-Mo microfilaments extruded from oxide- or metal-powder inks",
abstract = "3D ink-extrusion of powders followed by sintering is an emerging alternative to beam-based additive manufacturing, capable of creating 3D metallic objects from 1D-extruded microfilaments. Here, in situ synchrotron X-ray diffraction and tomography are combined to study the phase evolution, alloy formation and sinter-densification of Fe-20Ni-5Mo (at.%) microfilaments. The filaments are <200 µm in diameter and are extruded from inks containing a blend of Fe2O3+NiO+MoO3 µm-sized oxide particles. Blended oxide inks show rapid reduction and homogenization during heating to 1373 K in H2 accompanied by fast densification and interdiffusion. The resulting homogenous Fe-20Ni and Fe-20Ni-5Mo alloys reach near-full density within minutes at 1373 K. When using Ar-5%H2, co-reduction and interdiffusion are slower and the sequence of reduction is changed. During H2 co-reduction, Fe2O3 and NiO show synergistic effects. The onset temperature of reduction is mutually reduced and the conversion rates to Fe3O4 and Ni are increased. Fe-20Ni-5Mo microfilaments printed with coarser, elemental powder (~3 µm) show slower sintering and compositional homogenization as compared to inks of blended oxide, as the coarser metal particles provide lower surface/volume ratio and higher diffusion distances. Using micron-size oxide powders (rather than coarser metallic particles) accelerates kinetics of reduction, sintering and interdiffusion which reduces costs and energy in 3D ink-printing, improves filament surface quality, but doubles the extent of shrinkage.",
keywords = "Additive manufacturing, Reduction, Sintering, X-ray diffraction, X-ray tomography",
author = "C. Kenel and T. Davenport and X. Li and Shah, {R. N.} and Dunand, {D. C.}",
note = "Funding Information: CK received funding from the Swiss National Science Foundation as an Early Postdoc Mobility fellowship under grant No. 172180 . The authors gratefully acknowledge Prof. S. Haile (Northwestern University) for providing access to her lab for the TGA measurements, the Paul Scherrer Institut, Villigen, Switzerland and dr. N. Casati for the provision of beam-time for diffraction experiments at the Material Science beamline of the Swiss Light Source and M. Lange for technical support. X-ray tomography was performed at the DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) located at Sector 5 of the Advanced Photon Source (APS) with support of dr. D. Keane and dr. M. Guise. DND-CAT is supported by Northwestern University , E.I. DuPont de Nemours & Co., and The Dow Chemical Company. This research used resources of the APS, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357 . Funding Information: CK received funding from the Swiss National Science Foundation as an Early Postdoc Mobility fellowship under grant No. 172180. The authors gratefully acknowledge Prof. S. Haile (Northwestern University) for providing access to her lab for the TGA measurements, the Paul Scherrer Institut, Villigen, Switzerland and dr. N. Casati for the provision of beam-time for diffraction experiments at the Material Science beamline of the Swiss Light Source and M. Lange for technical support. X-ray tomography was performed at the DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) located at Sector 5 of the Advanced Photon Source (APS) with support of dr. D. Keane and dr. M. Guise. DND-CAT is supported by Northwestern University, E.I. DuPont de Nemours & Co. and The Dow Chemical Company. This research used resources of the APS, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. DCD discloses a financial interest in Metalprinting Inc. (South Korea) which is active in ink-based materials printing. RNS is a co-founder of, and shareholder in, DimensionInx, LLC, which develops and manufactures advanced manufacturing-compatible materials and devices for medical and non-medical applications. Publisher Copyright: {\textcopyright} 2020 Acta Materialia Inc.",
year = "2020",
month = jul,
doi = "10.1016/j.actamat.2020.04.038",
language = "English (US)",
volume = "193",
pages = "51--60",
journal = "Acta Materialia",
issn = "1359-6454",
publisher = "Elsevier Limited",
}