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Title: Laser-metal interaction dynamics during additive manufacturing resolved by detection of thermally-induced electron emission

Abstract

In situ monitoring is required to improve the understanding and increase the reliability of additive manufacturing methods such as laser powder bed fusion (LPBF). Current diagnostic methods for LPBF capture optical images, X-ray radiographs, or measure the emission of thermal or acoustic signals from the component. Herein, a methodology based on the thermal emission of electrons - thermionic emission - from the metal surface during LPBF is proposed which can resolve laser-material interaction dynamics. The high sensitivity of thermionic emission to surface temperature and surface morphology is revealed to enable precise determination of the transition between conduction and keyhole mode melting regimes. Increases in thermionic emission are correlated to laser scanning conditions that give rise to pore formation and regions where surface defects are pronounced. The information presented here is a critical step in furthering our understanding and validation of laser-based metal additive manufacturing.

Authors:
 [1];  [2];  [3];  [3];  [3];  [3];  [3]
  1. Stanford Univ., CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Colorado School of Mines, Golden, CO (United States)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program
OSTI Identifier:
1735805
Report Number(s):
LLNL-JRNL-807184
Journal ID: ISSN 2662-4443; 1012675
Grant/Contract Number:  
AC52-07NA27344; 19-FS-037; 18-SI-003
Resource Type:
Accepted Manuscript
Journal Name:
Communications Materials
Additional Journal Information:
Journal Volume: 1; Journal Issue: 1; Journal ID: ISSN 2662-4443
Publisher:
Springer Nature
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Characterization and analytical techniques; metals and alloys

Citation Formats

DePond, Philip J., Fuller, John C., Khairallah, Saad A., Angus, Justin R., Guss, Gabe, Matthews, Manyalibo J., and Martin, Aiden A.. Laser-metal interaction dynamics during additive manufacturing resolved by detection of thermally-induced electron emission. United States: N. p., 2020. Web. https://doi.org/10.1038/s43246-020-00094-y.
DePond, Philip J., Fuller, John C., Khairallah, Saad A., Angus, Justin R., Guss, Gabe, Matthews, Manyalibo J., & Martin, Aiden A.. Laser-metal interaction dynamics during additive manufacturing resolved by detection of thermally-induced electron emission. United States. https://doi.org/10.1038/s43246-020-00094-y
DePond, Philip J., Fuller, John C., Khairallah, Saad A., Angus, Justin R., Guss, Gabe, Matthews, Manyalibo J., and Martin, Aiden A.. Fri . "Laser-metal interaction dynamics during additive manufacturing resolved by detection of thermally-induced electron emission". United States. https://doi.org/10.1038/s43246-020-00094-y. https://www.osti.gov/servlets/purl/1735805.
@article{osti_1735805,
title = {Laser-metal interaction dynamics during additive manufacturing resolved by detection of thermally-induced electron emission},
author = {DePond, Philip J. and Fuller, John C. and Khairallah, Saad A. and Angus, Justin R. and Guss, Gabe and Matthews, Manyalibo J. and Martin, Aiden A.},
abstractNote = {In situ monitoring is required to improve the understanding and increase the reliability of additive manufacturing methods such as laser powder bed fusion (LPBF). Current diagnostic methods for LPBF capture optical images, X-ray radiographs, or measure the emission of thermal or acoustic signals from the component. Herein, a methodology based on the thermal emission of electrons - thermionic emission - from the metal surface during LPBF is proposed which can resolve laser-material interaction dynamics. The high sensitivity of thermionic emission to surface temperature and surface morphology is revealed to enable precise determination of the transition between conduction and keyhole mode melting regimes. Increases in thermionic emission are correlated to laser scanning conditions that give rise to pore formation and regions where surface defects are pronounced. The information presented here is a critical step in furthering our understanding and validation of laser-based metal additive manufacturing.},
doi = {10.1038/s43246-020-00094-y},
journal = {Communications Materials},
number = 1,
volume = 1,
place = {United States},
year = {2020},
month = {11}
}

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