Laser Powder Bed Fusion of Molybdenum and Mo-0.1SiC Studied by Positron Annihilation Lifetime Spectroscopy and Electron Backscatter Diffraction Methods
Positron annihilation lifetime spectroscopy (PALS) has been used for the first time to investigate the microstructure of additively manufactured molybdenum. Despite the wide applicability of positron annihilation spectroscopy techniques to the defect analysis of metals, they have only been used spar...
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2023-02-01
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| Online Access: | https://www.mdpi.com/1996-1944/16/4/1636 |
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| author | Nathan E. Ellsworth Joshua R. Machacek Ryan A. Kemnitz Cayla C. Eckley Brianna M. Sexton Joel A. Gearhart Larry W. Burggraf |
| author_facet | Nathan E. Ellsworth Joshua R. Machacek Ryan A. Kemnitz Cayla C. Eckley Brianna M. Sexton Joel A. Gearhart Larry W. Burggraf |
| author_sort | Nathan E. Ellsworth |
| collection | DOAJ |
| description | Positron annihilation lifetime spectroscopy (PALS) has been used for the first time to investigate the microstructure of additively manufactured molybdenum. Despite the wide applicability of positron annihilation spectroscopy techniques to the defect analysis of metals, they have only been used sparingly to monitor the microstructural evolution of additively manufactured metals. Molybdenum and molybdenum with a dilute addition (0.1 wt%) of nano-sized silicon carbide, prepared via laser powder bed fusion (LPBF) at four different scan speeds: 100, 200, 400, and 800 mm/s, were studied by PALS and compared with electron backscatter diffraction analysis. The aim of this study was to clarify the extent to which PALS can be used to identify microstructural changes resulting from varying LPBF process parameters. Grain sizes and misorientation results do not correlate with positron lifetimes indicating the positrons are sampling regions within the grains. Positron annihilation spectroscopy identified the presence of dislocations and nano-voids not revealed through electron microscopy techniques and correlated with the findings of SiO<sub>2</sub> nanoparticles in the samples prepared with silicon carbide. The comparison of results indicates the usefulness of positron techniques to characterize nano-structure in additively manufactured metals due to the significant increase in atomic-level information. |
| first_indexed | 2024-03-11T08:29:06Z |
| format | Article |
| id | doaj.art-1dd449574926404babbb0f112b2ae586 |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-11T08:29:06Z |
| publishDate | 2023-02-01 |
| publisher | MDPI AG |
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| series | Materials |
| spelling | doaj.art-1dd449574926404babbb0f112b2ae5862023-11-16T21:52:29ZengMDPI AGMaterials1996-19442023-02-01164163610.3390/ma16041636Laser Powder Bed Fusion of Molybdenum and Mo-0.1SiC Studied by Positron Annihilation Lifetime Spectroscopy and Electron Backscatter Diffraction MethodsNathan E. Ellsworth0Joshua R. Machacek1Ryan A. Kemnitz2Cayla C. Eckley3Brianna M. Sexton4Joel A. Gearhart5Larry W. Burggraf6Department of Engineering Physics, Air Force Institute of Technology, 2950 Hobson Way, Wright-Patterson AFB, OH 45433, USAResearch School of Physics, Australian National University, Canberra 2601, AustraliaDepartment of Aeronautics and Astronautics, Air Force Institute of Technology, 2950 Hobson Way, Wright-Patterson AFB, OH 45433, USADepartment of Aeronautics and Astronautics, Air Force Institute of Technology, 2950 Hobson Way, Wright-Patterson AFB, OH 45433, USADepartment of Aeronautics and Astronautics, Air Force Institute of Technology, 2950 Hobson Way, Wright-Patterson AFB, OH 45433, USADepartment of Engineering Physics, Air Force Institute of Technology, 2950 Hobson Way, Wright-Patterson AFB, OH 45433, USADepartment of Engineering Physics, Air Force Institute of Technology, 2950 Hobson Way, Wright-Patterson AFB, OH 45433, USAPositron annihilation lifetime spectroscopy (PALS) has been used for the first time to investigate the microstructure of additively manufactured molybdenum. Despite the wide applicability of positron annihilation spectroscopy techniques to the defect analysis of metals, they have only been used sparingly to monitor the microstructural evolution of additively manufactured metals. Molybdenum and molybdenum with a dilute addition (0.1 wt%) of nano-sized silicon carbide, prepared via laser powder bed fusion (LPBF) at four different scan speeds: 100, 200, 400, and 800 mm/s, were studied by PALS and compared with electron backscatter diffraction analysis. The aim of this study was to clarify the extent to which PALS can be used to identify microstructural changes resulting from varying LPBF process parameters. Grain sizes and misorientation results do not correlate with positron lifetimes indicating the positrons are sampling regions within the grains. Positron annihilation spectroscopy identified the presence of dislocations and nano-voids not revealed through electron microscopy techniques and correlated with the findings of SiO<sub>2</sub> nanoparticles in the samples prepared with silicon carbide. The comparison of results indicates the usefulness of positron techniques to characterize nano-structure in additively manufactured metals due to the significant increase in atomic-level information.https://www.mdpi.com/1996-1944/16/4/1636additive manufacturinglaser powder bed fusionselective laser meltingmolybdenumsilicon carbidenanoparticles |
| spellingShingle | Nathan E. Ellsworth Joshua R. Machacek Ryan A. Kemnitz Cayla C. Eckley Brianna M. Sexton Joel A. Gearhart Larry W. Burggraf Laser Powder Bed Fusion of Molybdenum and Mo-0.1SiC Studied by Positron Annihilation Lifetime Spectroscopy and Electron Backscatter Diffraction Methods Materials additive manufacturing laser powder bed fusion selective laser melting molybdenum silicon carbide nanoparticles |
| title | Laser Powder Bed Fusion of Molybdenum and Mo-0.1SiC Studied by Positron Annihilation Lifetime Spectroscopy and Electron Backscatter Diffraction Methods |
| title_full | Laser Powder Bed Fusion of Molybdenum and Mo-0.1SiC Studied by Positron Annihilation Lifetime Spectroscopy and Electron Backscatter Diffraction Methods |
| title_fullStr | Laser Powder Bed Fusion of Molybdenum and Mo-0.1SiC Studied by Positron Annihilation Lifetime Spectroscopy and Electron Backscatter Diffraction Methods |
| title_full_unstemmed | Laser Powder Bed Fusion of Molybdenum and Mo-0.1SiC Studied by Positron Annihilation Lifetime Spectroscopy and Electron Backscatter Diffraction Methods |
| title_short | Laser Powder Bed Fusion of Molybdenum and Mo-0.1SiC Studied by Positron Annihilation Lifetime Spectroscopy and Electron Backscatter Diffraction Methods |
| title_sort | laser powder bed fusion of molybdenum and mo 0 1sic studied by positron annihilation lifetime spectroscopy and electron backscatter diffraction methods |
| topic | additive manufacturing laser powder bed fusion selective laser melting molybdenum silicon carbide nanoparticles |
| url | https://www.mdpi.com/1996-1944/16/4/1636 |
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