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Air Force Institute of Technology

Mechanical Engineering

Selective laser melting

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Full-Text Articles in Engineering

Influence Of Nano-Sized Sic On The Laser Powder Bed Fusion Of Molybdenum, Nathan E. Ellsworth, Ryan A. Kemnitz, Cayla C. Eckley, Brianna M. Sexton, Cynthia T. Bowers, Joshua R. Machacek, Larry W. Burggraf Sep 2022

Influence Of Nano-Sized Sic On The Laser Powder Bed Fusion Of Molybdenum, Nathan E. Ellsworth, Ryan A. Kemnitz, Cayla C. Eckley, Brianna M. Sexton, Cynthia T. Bowers, Joshua R. Machacek, Larry W. Burggraf

Faculty Publications

Consolidation of pure molybdenum through laser powder bed fusion and other additive manufacturing techniques is complicated by a high melting temperature, thermal conductivity and ductile-to-brittle transition temperature. Nano-sized SiC particles (0.1 wt%) were homogeneously mixed with molybdenum powder and the printing characteristics, chemical composition, microstructure, mechanical properties were compared to pure molybdenum for scan speeds of 100, 200, 400, and 800 mm/s. The addition of SiC improved the optically determined density and flexural strength at 400 mm/s by 92% and 80%, respectively. The oxygen content was reduced by an average of 52% over the four scan speeds analyzed. Two mechanisms …


Investigation Of Additively Manufactured Molybdenum-Tungsten-Rhenium Alloys, Randolph T. Abaya Mar 2022

Investigation Of Additively Manufactured Molybdenum-Tungsten-Rhenium Alloys, Randolph T. Abaya

Theses and Dissertations

The process of creating metal components through additive manufacturing is changing the way different industries can avoid the shortcomings of traditional metal production. Metals such as tungsten, molybdenum, and rhenium have many advantages for different applications, especially when alloyed together. In this study, an additively manufactured alloy containing 70% molybdenum, 25% tungsten, and 5% rhenium (70Mo-25W-5Re) is tested for its strength, ductility, hardness, and porosity. The 70Mo-25W-5Re alloy is printed through Laser Powder Bed Fusion (LPBF) under different conditions such as printing speed and printing atmosphere. Additionally, the effects of post printing heat treatment are conducted to understand the advantages …


Effects Of A Nitrogen And Hydrogen Build Atmosphere On The Properties Of Additively Manufactured Tungsten, Dana C. Madsen Mar 2022

Effects Of A Nitrogen And Hydrogen Build Atmosphere On The Properties Of Additively Manufactured Tungsten, Dana C. Madsen

Theses and Dissertations

Additively manufactured tungsten was printed in pure nitrogen, nitrogen-2.5% hydrogen, and nitrogen-5% hydrogen atmospheres as part of a 2^3 full factorial designed experiment and subjected to room temperature and high-temperature three-point-bend testing, chemical analysis, hardness testing, and microstructural imaging techniques. The pure nitrogen specimens exhibited the highest strength and ductility at both high temperature and room temperature. Chemical analysis showed a 2-8x reduction in compositional oxygen relative to unprocessed powder. Hardness values for all samples was between 306.8 and 361.5 HV1. It is proposed that adding hydrogen into the build atmosphere reduced the available energy density for tungsten melting by …