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In situ observation of the impact of hydrogen bubbles in Al-Cu melt on directional dendritic solidification

Werner, Thomas and Becker, Maike and Baumann, Juliane and Pickmann, Christoph and Sturz, Laszlo and Kargl, Florian (2021) In situ observation of the impact of hydrogen bubbles in Al-Cu melt on directional dendritic solidification. Journal of Materials Science, 56, pp. 8225-8242. Springer. doi: 10.1007/s10853-020-05748-3. ISSN 0022-2461.

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Official URL: https://link.springer.com/article/10.1007/s10853-020-05748-3


Much research has already been focused on the solid-bubble interaction in the interdendritic space for solidifying materials. However, commonly, bubble nucleation is not limited to the mushy zone but also occurs in the liquid melt. In the present research on an Al-10%wt. Cu alloy, the interaction between these bubbles and the approaching solidification front becomes apparent under in situ X-radiography and allows for new insights into the influence of bubbles on the solidifying microstructure. The observed effects comprise bulging of the solidification front toward the bubble, bending of dendrites in front of the bubble, coronal outgrowths surrounding the bubbles, as well as bubble growth, bubble pushing, and bubble eruption. It is found that for the present Al-Cu alloy, the local variation in the solidification speed can be attributed to the bubbles' insulating properties. The range of this effect was observed to be up to 900mum, depending on the bubble diameter, locally increasing solidification speed by up to 350%. The influences of Marangoni vortices and coronal nucleation of misoriented dendrites around bubbles on the homogeneity of the microstructure are discussed. A comparison with experiments on model alloys and simulations from various other studies highlights the similarities and differences to this metallic alloy system.

Item URL in elib:https://elib.dlr.de/141525/
Document Type:Article
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Title:In situ observation of the impact of hydrogen bubbles in Al-Cu melt on directional dendritic solidification
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Becker, MaikeUNSPECIFIEDhttps://orcid.org/0000-0002-6732-5411UNSPECIFIED
Kargl, FlorianInstitut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, GermanyUNSPECIFIEDUNSPECIFIED
Date:18 January 2021
Journal or Publication Title:Journal of Materials Science
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:pp. 8225-8242
Series Name:Metals & Corrosion
Keywords:Al alloys, directional solidification, hydrogen bubbles, porosity, X-radiography, dendrites
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Research under Space Conditions
DLR - Research area:Raumfahrt
DLR - Program:R FR - Research under Space Conditions
DLR - Research theme (Project):R - Material Design and New Materials, R - Materials Research and Microgravity (MuM)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Physics in Space
Deposited By: Kargl, Dr Florian
Deposited On:30 Mar 2021 20:55
Last Modified:28 Mar 2023 23:59

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