Live record of vortex-shaped flow by microgravity solidification
A unique type of vortex-shaped microstructure reflecting the flow pattern during the microgravity solidification formed in Al70Ag20Ge10 alloy droplets using drop tube technique. A 2D axisymmetric model coupling heat transfer, fluid flow with phase change was established to simulate the fluid flow va...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Elsevier
2021-11-01
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| Series: | Materials & Design |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0264127521005335 |
| _version_ | 1818440954761183232 |
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| author | H.R. Li Y. Ruan |
| author_facet | H.R. Li Y. Ruan |
| author_sort | H.R. Li |
| collection | DOAJ |
| description | A unique type of vortex-shaped microstructure reflecting the flow pattern during the microgravity solidification formed in Al70Ag20Ge10 alloy droplets using drop tube technique. A 2D axisymmetric model coupling heat transfer, fluid flow with phase change was established to simulate the fluid flow variation of alloy droplets during microgravity solidification. The Stokes motion was suppressed and the Marangoni motion was prominent in driving the vortex-shaped flow. The melt flow affected the phase selection, consequently the Ag2Al phase nucleated primarily instead of (Al) phase under near-equilibrium solidification, and the flow pattern was preserved during the rapid growth of the metastable Ag2Al dendrites. The Marangoni effect was weakened with the decrease of droplet size, and anomalous (Al) + Ag2Al and intergranular (Al) + (Ge) eutectics formed owing to the enhanced nucleation and growth competition among phases. In comparison, Al70Ag20Ge10 alloy was solidified under gravity condition by DSC and vacuum arc melting methods respectively. No vortex-shaped microstructure formed in DSC sample ascribed to the suppressed natural convection at small cooling rate. During arc melting, the electromagnetic force and enhanced natural convection caused strong turbulent flow, the metastable Ag2Al dendrites rapidly formed with increased vortex density. |
| first_indexed | 2024-12-14T18:20:34Z |
| format | Article |
| id | doaj.art-5fb7e9b63cb04d8088ed4cc47bc69b9f |
| institution | Directory Open Access Journal |
| issn | 0264-1275 |
| language | English |
| last_indexed | 2024-12-14T18:20:34Z |
| publishDate | 2021-11-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Materials & Design |
| spelling | doaj.art-5fb7e9b63cb04d8088ed4cc47bc69b9f2022-12-21T22:52:05ZengElsevierMaterials & Design0264-12752021-11-01209109979Live record of vortex-shaped flow by microgravity solidificationH.R. Li0Y. Ruan1MOE Key Laboratory of Materials Physics and Chemistry under Extraordinary Conditions, School of Physical Science and Technology, Northwestern Polytechnical University, Xi’an 710072, ChinaCorresponding author.; MOE Key Laboratory of Materials Physics and Chemistry under Extraordinary Conditions, School of Physical Science and Technology, Northwestern Polytechnical University, Xi’an 710072, ChinaA unique type of vortex-shaped microstructure reflecting the flow pattern during the microgravity solidification formed in Al70Ag20Ge10 alloy droplets using drop tube technique. A 2D axisymmetric model coupling heat transfer, fluid flow with phase change was established to simulate the fluid flow variation of alloy droplets during microgravity solidification. The Stokes motion was suppressed and the Marangoni motion was prominent in driving the vortex-shaped flow. The melt flow affected the phase selection, consequently the Ag2Al phase nucleated primarily instead of (Al) phase under near-equilibrium solidification, and the flow pattern was preserved during the rapid growth of the metastable Ag2Al dendrites. The Marangoni effect was weakened with the decrease of droplet size, and anomalous (Al) + Ag2Al and intergranular (Al) + (Ge) eutectics formed owing to the enhanced nucleation and growth competition among phases. In comparison, Al70Ag20Ge10 alloy was solidified under gravity condition by DSC and vacuum arc melting methods respectively. No vortex-shaped microstructure formed in DSC sample ascribed to the suppressed natural convection at small cooling rate. During arc melting, the electromagnetic force and enhanced natural convection caused strong turbulent flow, the metastable Ag2Al dendrites rapidly formed with increased vortex density.http://www.sciencedirect.com/science/article/pii/S0264127521005335MicrogravityRapid solidificationDrop tubeMicrostructureConvection |
| spellingShingle | H.R. Li Y. Ruan Live record of vortex-shaped flow by microgravity solidification Materials & Design Microgravity Rapid solidification Drop tube Microstructure Convection |
| title | Live record of vortex-shaped flow by microgravity solidification |
| title_full | Live record of vortex-shaped flow by microgravity solidification |
| title_fullStr | Live record of vortex-shaped flow by microgravity solidification |
| title_full_unstemmed | Live record of vortex-shaped flow by microgravity solidification |
| title_short | Live record of vortex-shaped flow by microgravity solidification |
| title_sort | live record of vortex shaped flow by microgravity solidification |
| topic | Microgravity Rapid solidification Drop tube Microstructure Convection |
| url | http://www.sciencedirect.com/science/article/pii/S0264127521005335 |
| work_keys_str_mv | AT hrli liverecordofvortexshapedflowbymicrogravitysolidification AT yruan liverecordofvortexshapedflowbymicrogravitysolidification |