Effect of Cooling Rate on Nano-Eutectic Formation in Laser Surface Remelted and Rare Earth Modified Hypereutectic Al-20Si Alloys
Laser Surface Remelting (LSR) was applied to arc-melted Al-20Si-0.2Sr, Al-20Si-0.2Ce, and Al-20Si hypereutectic alloys to refine microstructures. Experiments revealed that microstructures in the melt pool varied from fully eutectic to a mixture of Al dendrites and inter-dendritic eutectic. We calcul...
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MDPI AG
2022-05-01
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| Online Access: | https://www.mdpi.com/2073-4352/12/5/750 |
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| author | Metin Kayitmazbatir Huai-Hsun Lien Jyoti Mazumder Jian Wang Amit Misra |
| author_facet | Metin Kayitmazbatir Huai-Hsun Lien Jyoti Mazumder Jian Wang Amit Misra |
| author_sort | Metin Kayitmazbatir |
| collection | DOAJ |
| description | Laser Surface Remelting (LSR) was applied to arc-melted Al-20Si-0.2Sr, Al-20Si-0.2Ce, and Al-20Si hypereutectic alloys to refine microstructures. Experiments revealed that microstructures in the melt pool varied from fully eutectic to a mixture of Al dendrites and inter-dendritic eutectic. We calculated cooling rates using the Eagar-Tsai model and correlated cooling rates with characteristic microstructures, revealing that a cooling rate on the order of 10<sup>4</sup> K/s could lead to maximized fully eutectic microstructure morphology. Due to rapid solidification, the Si composition in the LSR eutectic was measured at 18.2 wt.%, higher than the equilibrium eutectic composition of 12.6 wt.%Si. Compared to Al-20Si, Ce addition had no significant effect on the volume fraction of the fully eutectic structure but refined Si fibers to approximately 30 nm in diameter. Sr addition did not further refine the diameter of eutectic Si fibers compared to Al-20Si but increased the volume fraction of the fully eutectic microstructure morphology. The refinement ratio (φ) of the Si fiber diameter from the bottom of the melt pool to the surface for the three alloys was similar, at around 28%. The established correlation between the cooling rate and the size and morphology of the microstructure within the melt pool will enable tailoring of the microstructure in laser-processed as well as deposited alloys for high strength and plasticity. |
| first_indexed | 2024-03-10T03:04:47Z |
| format | Article |
| id | doaj.art-5834987ceb814fa2a80d6a53fde1dc91 |
| institution | Directory Open Access Journal |
| issn | 2073-4352 |
| language | English |
| last_indexed | 2024-03-10T03:04:47Z |
| publishDate | 2022-05-01 |
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| record_format | Article |
| series | Crystals |
| spelling | doaj.art-5834987ceb814fa2a80d6a53fde1dc912023-11-23T10:36:29ZengMDPI AGCrystals2073-43522022-05-0112575010.3390/cryst12050750Effect of Cooling Rate on Nano-Eutectic Formation in Laser Surface Remelted and Rare Earth Modified Hypereutectic Al-20Si AlloysMetin Kayitmazbatir0Huai-Hsun Lien1Jyoti Mazumder2Jian Wang3Amit Misra4Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USADepartment of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109, USADepartment of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USADepartment of Mechanical Engineering, University of Nebraska, Lincoln, NE 68588, USADepartment of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USALaser Surface Remelting (LSR) was applied to arc-melted Al-20Si-0.2Sr, Al-20Si-0.2Ce, and Al-20Si hypereutectic alloys to refine microstructures. Experiments revealed that microstructures in the melt pool varied from fully eutectic to a mixture of Al dendrites and inter-dendritic eutectic. We calculated cooling rates using the Eagar-Tsai model and correlated cooling rates with characteristic microstructures, revealing that a cooling rate on the order of 10<sup>4</sup> K/s could lead to maximized fully eutectic microstructure morphology. Due to rapid solidification, the Si composition in the LSR eutectic was measured at 18.2 wt.%, higher than the equilibrium eutectic composition of 12.6 wt.%Si. Compared to Al-20Si, Ce addition had no significant effect on the volume fraction of the fully eutectic structure but refined Si fibers to approximately 30 nm in diameter. Sr addition did not further refine the diameter of eutectic Si fibers compared to Al-20Si but increased the volume fraction of the fully eutectic microstructure morphology. The refinement ratio (φ) of the Si fiber diameter from the bottom of the melt pool to the surface for the three alloys was similar, at around 28%. The established correlation between the cooling rate and the size and morphology of the microstructure within the melt pool will enable tailoring of the microstructure in laser-processed as well as deposited alloys for high strength and plasticity.https://www.mdpi.com/2073-4352/12/5/750laser surface remeltinghypereutectic Al-Sirare earth element alloying |
| spellingShingle | Metin Kayitmazbatir Huai-Hsun Lien Jyoti Mazumder Jian Wang Amit Misra Effect of Cooling Rate on Nano-Eutectic Formation in Laser Surface Remelted and Rare Earth Modified Hypereutectic Al-20Si Alloys Crystals laser surface remelting hypereutectic Al-Si rare earth element alloying |
| title | Effect of Cooling Rate on Nano-Eutectic Formation in Laser Surface Remelted and Rare Earth Modified Hypereutectic Al-20Si Alloys |
| title_full | Effect of Cooling Rate on Nano-Eutectic Formation in Laser Surface Remelted and Rare Earth Modified Hypereutectic Al-20Si Alloys |
| title_fullStr | Effect of Cooling Rate on Nano-Eutectic Formation in Laser Surface Remelted and Rare Earth Modified Hypereutectic Al-20Si Alloys |
| title_full_unstemmed | Effect of Cooling Rate on Nano-Eutectic Formation in Laser Surface Remelted and Rare Earth Modified Hypereutectic Al-20Si Alloys |
| title_short | Effect of Cooling Rate on Nano-Eutectic Formation in Laser Surface Remelted and Rare Earth Modified Hypereutectic Al-20Si Alloys |
| title_sort | effect of cooling rate on nano eutectic formation in laser surface remelted and rare earth modified hypereutectic al 20si alloys |
| topic | laser surface remelting hypereutectic Al-Si rare earth element alloying |
| url | https://www.mdpi.com/2073-4352/12/5/750 |
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