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The Mechanism of Dendrite Formation in a Solid-State Transformation of High Aluminum Fe-Al Alloys

The mechanism of solid-state dendrite formation in high-aluminum Fe-Al alloys is not clear. Applying an in-situ observation technique, the real-time formation and growth of FeAl solid-state dendrites during the eutectoid decomposition of the high-temperature phase Fe(5)Al(8) is visualized. In-situ e...

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Autores principales: Yang, Haodong, Zhang, Yifan, Zhang, An, Stein, Frank, Xu, Zhengbing, Tang, Zhichao, Ren, Dangjing, Zeng, Jianmin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10096059/
https://www.ncbi.nlm.nih.gov/pubmed/37048985
http://dx.doi.org/10.3390/ma16072691
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author Yang, Haodong
Zhang, Yifan
Zhang, An
Stein, Frank
Xu, Zhengbing
Tang, Zhichao
Ren, Dangjing
Zeng, Jianmin
author_facet Yang, Haodong
Zhang, Yifan
Zhang, An
Stein, Frank
Xu, Zhengbing
Tang, Zhichao
Ren, Dangjing
Zeng, Jianmin
author_sort Yang, Haodong
collection PubMed
description The mechanism of solid-state dendrite formation in high-aluminum Fe-Al alloys is not clear. Applying an in-situ observation technique, the real-time formation and growth of FeAl solid-state dendrites during the eutectoid decomposition of the high-temperature phase Fe(5)Al(8) is visualized. In-situ experiments by HT-CSLM reveal that proeutectoid FeAl usually does not preferentially nucleate at grain boundaries regardless of rapid or slow cooling conditions. The critical radii for generating morphological instability are 1.2 μm and 0.9 μm for slow and rapid cooling, respectively. The morphology after both slow and rapid cooling exhibits dendrites, while there are differences in the size and critical instability radius R(c), which are attributed to the different supersaturation S and the number of protrusions l. The combination of crystallographic and thermodynamic analysis indicates that solid-state dendrites only exist on the hypoeutectoid side in high-aluminum Fe-Al alloys. A large number of lattice defects in the parent phase provides an additional driving force for nucleation, leading to coherent nucleation from the interior of the parent phase grains based on the orientation relationship {[Formula: see text] 0}(Fe5Al8)//{[Formula: see text] 10}(FeAl), <11 [Formula: see text] >(Fe5Al8)//<11 [Formula: see text] >(FeAl). The maximum release of misfit strain energy leads to the preferential growth of the primary arm of the nucleus along <11 [Formula: see text] > {[Formula: see text] 10}. During the rapid cooling process, a large supersaturation is induced in the matrix, driving the Al atoms to undergo unstable uphill diffusion and causing variations in the concentration gradient as well as generating constitutional undercooling, ultimately leading to morphological instability and the growth of secondary arms.
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spelling pubmed-100960592023-04-13 The Mechanism of Dendrite Formation in a Solid-State Transformation of High Aluminum Fe-Al Alloys Yang, Haodong Zhang, Yifan Zhang, An Stein, Frank Xu, Zhengbing Tang, Zhichao Ren, Dangjing Zeng, Jianmin Materials (Basel) Article The mechanism of solid-state dendrite formation in high-aluminum Fe-Al alloys is not clear. Applying an in-situ observation technique, the real-time formation and growth of FeAl solid-state dendrites during the eutectoid decomposition of the high-temperature phase Fe(5)Al(8) is visualized. In-situ experiments by HT-CSLM reveal that proeutectoid FeAl usually does not preferentially nucleate at grain boundaries regardless of rapid or slow cooling conditions. The critical radii for generating morphological instability are 1.2 μm and 0.9 μm for slow and rapid cooling, respectively. The morphology after both slow and rapid cooling exhibits dendrites, while there are differences in the size and critical instability radius R(c), which are attributed to the different supersaturation S and the number of protrusions l. The combination of crystallographic and thermodynamic analysis indicates that solid-state dendrites only exist on the hypoeutectoid side in high-aluminum Fe-Al alloys. A large number of lattice defects in the parent phase provides an additional driving force for nucleation, leading to coherent nucleation from the interior of the parent phase grains based on the orientation relationship {[Formula: see text] 0}(Fe5Al8)//{[Formula: see text] 10}(FeAl), <11 [Formula: see text] >(Fe5Al8)//<11 [Formula: see text] >(FeAl). The maximum release of misfit strain energy leads to the preferential growth of the primary arm of the nucleus along <11 [Formula: see text] > {[Formula: see text] 10}. During the rapid cooling process, a large supersaturation is induced in the matrix, driving the Al atoms to undergo unstable uphill diffusion and causing variations in the concentration gradient as well as generating constitutional undercooling, ultimately leading to morphological instability and the growth of secondary arms. MDPI 2023-03-28 /pmc/articles/PMC10096059/ /pubmed/37048985 http://dx.doi.org/10.3390/ma16072691 Text en © 2023 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Yang, Haodong
Zhang, Yifan
Zhang, An
Stein, Frank
Xu, Zhengbing
Tang, Zhichao
Ren, Dangjing
Zeng, Jianmin
The Mechanism of Dendrite Formation in a Solid-State Transformation of High Aluminum Fe-Al Alloys
title The Mechanism of Dendrite Formation in a Solid-State Transformation of High Aluminum Fe-Al Alloys
title_full The Mechanism of Dendrite Formation in a Solid-State Transformation of High Aluminum Fe-Al Alloys
title_fullStr The Mechanism of Dendrite Formation in a Solid-State Transformation of High Aluminum Fe-Al Alloys
title_full_unstemmed The Mechanism of Dendrite Formation in a Solid-State Transformation of High Aluminum Fe-Al Alloys
title_short The Mechanism of Dendrite Formation in a Solid-State Transformation of High Aluminum Fe-Al Alloys
title_sort mechanism of dendrite formation in a solid-state transformation of high aluminum fe-al alloys
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10096059/
https://www.ncbi.nlm.nih.gov/pubmed/37048985
http://dx.doi.org/10.3390/ma16072691
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