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In situ Observation of Phase Transformation in MnAl(C) Magnetic Materials

The phase transformation in two modes, including both displacive and massive growth of τ-phase from ε-MnAl(C), was observed by in situ transmission electron microscopy. The exact temperature range for different phase transformation modes was determined by magnetic measurements. The displacive growth...

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Autores principales: Si, Ping-Zhan, Qian, Hui-Dong, Choi, Chul-Jin, Park, Jihoon, Han, Sangho, Ge, Hong-Liang, Shinde, Kiran P.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5615671/
https://www.ncbi.nlm.nih.gov/pubmed/28858231
http://dx.doi.org/10.3390/ma10091016
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author Si, Ping-Zhan
Qian, Hui-Dong
Choi, Chul-Jin
Park, Jihoon
Han, Sangho
Ge, Hong-Liang
Shinde, Kiran P.
author_facet Si, Ping-Zhan
Qian, Hui-Dong
Choi, Chul-Jin
Park, Jihoon
Han, Sangho
Ge, Hong-Liang
Shinde, Kiran P.
author_sort Si, Ping-Zhan
collection PubMed
description The phase transformation in two modes, including both displacive and massive growth of τ-phase from ε-MnAl(C), was observed by in situ transmission electron microscopy. The exact temperature range for different phase transformation modes was determined by magnetic measurements. The displacive growth of ε→τ in Mn(54)Al(46) (or Mn(54)Al(46)C(2.44)) occurs at temperatures below 650 K (or 766 K), above which both modes coexist. One-third or less of the ε-phase can be transformed into τ-phase via displacive mode while the remaining two-thirds or more via massive mode. In bulk τ-phase, most τ-nanocrystals formed via displacive mode are distributed in the matrix of large τ-grains that formed via massive mode. The typical massive growth rate of the τ-phase is 8–60 nm/s, while the displacive growth rate is low. A more complete understanding of the ε→τ phase transformations in the MnAl-based magnets was provided in this work, based on which the annealing process for ε→τ was optimized and thus high purity τ-phase with high saturation magnetization was obtained.
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spelling pubmed-56156712017-09-28 In situ Observation of Phase Transformation in MnAl(C) Magnetic Materials Si, Ping-Zhan Qian, Hui-Dong Choi, Chul-Jin Park, Jihoon Han, Sangho Ge, Hong-Liang Shinde, Kiran P. Materials (Basel) Article The phase transformation in two modes, including both displacive and massive growth of τ-phase from ε-MnAl(C), was observed by in situ transmission electron microscopy. The exact temperature range for different phase transformation modes was determined by magnetic measurements. The displacive growth of ε→τ in Mn(54)Al(46) (or Mn(54)Al(46)C(2.44)) occurs at temperatures below 650 K (or 766 K), above which both modes coexist. One-third or less of the ε-phase can be transformed into τ-phase via displacive mode while the remaining two-thirds or more via massive mode. In bulk τ-phase, most τ-nanocrystals formed via displacive mode are distributed in the matrix of large τ-grains that formed via massive mode. The typical massive growth rate of the τ-phase is 8–60 nm/s, while the displacive growth rate is low. A more complete understanding of the ε→τ phase transformations in the MnAl-based magnets was provided in this work, based on which the annealing process for ε→τ was optimized and thus high purity τ-phase with high saturation magnetization was obtained. MDPI 2017-08-31 /pmc/articles/PMC5615671/ /pubmed/28858231 http://dx.doi.org/10.3390/ma10091016 Text en © 2017 by the authors. 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 (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Si, Ping-Zhan
Qian, Hui-Dong
Choi, Chul-Jin
Park, Jihoon
Han, Sangho
Ge, Hong-Liang
Shinde, Kiran P.
In situ Observation of Phase Transformation in MnAl(C) Magnetic Materials
title In situ Observation of Phase Transformation in MnAl(C) Magnetic Materials
title_full In situ Observation of Phase Transformation in MnAl(C) Magnetic Materials
title_fullStr In situ Observation of Phase Transformation in MnAl(C) Magnetic Materials
title_full_unstemmed In situ Observation of Phase Transformation in MnAl(C) Magnetic Materials
title_short In situ Observation of Phase Transformation in MnAl(C) Magnetic Materials
title_sort in situ observation of phase transformation in mnal(c) magnetic materials
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5615671/
https://www.ncbi.nlm.nih.gov/pubmed/28858231
http://dx.doi.org/10.3390/ma10091016
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