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On the Formation of Spherical Metastable BCC Single Crystal Spatter Particles During Selective Laser Melting

42 Pages Posted: 10 Oct 2019 First Look: Under Review

See all articles by Daniel Galicki

Daniel Galicki

University of Tennessee, Knoxville - Department of Material Science and Engineering

B. C. Chakoumakos

Government of the United States of America - Neutron Scattering Division

Simon P. Ringer

The University of Sydney - Australian Centre for Microscopy & Microanalysis; The University of Sydney - School of Aerospace Mechanical and Mechatronic Engineering

Mehdi Eizadjou

The University of Sydney - School of Aerospace Mechanical and Mechatronic Engineering; The University of Sydney - Australian Centre for Microscopy & Microanalysis

Claudia J. Rawn

University of Tennessee, Knoxville - Department of Material Science and Engineering

Keita Nomoto

The University of Sydney - Australian Centre for Microscopy & Microanalysis; The University of Sydney - School of Aerospace Mechanical and Mechatronic Engineering

Sudarsanam S. Babu

University of Tennessee, Knoxville - Department of Material Science and Engineering; Government of the United States of America - Manufacturing Demonstration Facility; University of Tennessee, Knoxville - Mechanical, Aerospace and Biomedical Engineering Department

Abstract

Spatter particles, created during laser powder-bed-fusion (L-PBF) additive manufacturing process of 316L stainless steel, solidified as single-crystal, non-equilibrium, body-centered cubic (BCC) ferrite, which has not been reported before. This phenomenon is unusual considering that the composition of stainless steel 316L typically ensures primarily austenitic (face-centered-cubic, FCC) solidification. These particles were analyzed with multi-length scale microscopy and diffraction methods. Mechanisms for the competition between BCC and FCC phases were evaluated with computational thermodynamic and interface response function theories, as a function of thermal boundary conditions. These results indicate that the particles solidify at rapid rates and/or that conditions exist during solidification that allow for the nucleation and growth of the BCC phase that outcompete the FCC phase. The novelties of the work pertain to three aspects (i) discovery of fully single crystal BCC particles residing within spatter, (ii) rationalization of the mechanisms for this phenomenon with suites of characterization and modeling tools, as well as, (iii) the suggestion that L-PBF and associated spattering processes can be used as a synthesis route to produce metastable, single-crystal structures.

Keywords: L-PBF, Additive Manufacturing, solidification, steel, ferrite, oxide

Suggested Citation

Galicki, Daniel and Chakoumakos, B. C. and Ringer, Simon P. and Eizadjou, Mehdi and Rawn, Claudia J. and Nomoto, Keita and Babu, Sudarsanam S., On the Formation of Spherical Metastable BCC Single Crystal Spatter Particles During Selective Laser Melting. Available at SSRN: https://ssrn.com/abstract=3464657 or http://dx.doi.org/10.2139/ssrn.3464657

Daniel Galicki (Contact Author)

University of Tennessee, Knoxville - Department of Material Science and Engineering ( email )

Knoxville, TN 37996
United States

B. C. Chakoumakos

Government of the United States of America - Neutron Scattering Division

United States

Simon P. Ringer

The University of Sydney - Australian Centre for Microscopy & Microanalysis ( email )

Sydney
Australia

The University of Sydney - School of Aerospace Mechanical and Mechatronic Engineering ( email )

Sydney
Australia

Mehdi Eizadjou

The University of Sydney - School of Aerospace Mechanical and Mechatronic Engineering

Sydney
Australia

The University of Sydney - Australian Centre for Microscopy & Microanalysis

Sydney
Australia

Claudia J. Rawn

University of Tennessee, Knoxville - Department of Material Science and Engineering

Knoxville, TN 37996
United States

Keita Nomoto

The University of Sydney - Australian Centre for Microscopy & Microanalysis ( email )

Sydney
Australia

The University of Sydney - School of Aerospace Mechanical and Mechatronic Engineering ( email )

Sydney
Australia

Sudarsanam S. Babu

University of Tennessee, Knoxville - Department of Material Science and Engineering

Knoxville, TN 37996
United States

Government of the United States of America - Manufacturing Demonstration Facility

United States

University of Tennessee, Knoxville - Mechanical, Aerospace and Biomedical Engineering Department

Knoxville, TN 37996
United States

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