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Magnetism and ε-τ Phase Transformation in MnAl-Based Nanocomposite Magnets

Melt spun ribbons of Mn(53)Al(45)C(2) and Mn(52)Al(46)C(2) have been synthesized by rapid quenching of the melt with the purpose of monitoring the ε-τ phase transformation to show technologically feasible ways to increase magnetic parameters and to illustrate the viability of these alloys as the nex...

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Autores principales: Crisan, Alina Daniela, Leca, Aurel, Bartha, Cristina, Dan, Ioan, Crisan, Ovidiu
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8065736/
https://www.ncbi.nlm.nih.gov/pubmed/33807428
http://dx.doi.org/10.3390/nano11040896
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author Crisan, Alina Daniela
Leca, Aurel
Bartha, Cristina
Dan, Ioan
Crisan, Ovidiu
author_facet Crisan, Alina Daniela
Leca, Aurel
Bartha, Cristina
Dan, Ioan
Crisan, Ovidiu
author_sort Crisan, Alina Daniela
collection PubMed
description Melt spun ribbons of Mn(53)Al(45)C(2) and Mn(52)Al(46)C(2) have been synthesized by rapid quenching of the melt with the purpose of monitoring the ε-τ phase transformation to show technologically feasible ways to increase magnetic parameters and to illustrate the viability of these alloys as the next generation of rare earth (RE)-free magnets. By differential scanning calorimetry (DSC), activation energies and temperatures of onset of the ε-τ phase transformation were obtained. Structural analysis was performed using X-ray diffraction (XRD) and the resulting XRD patterns were quantitatively assessed using full profile Rietveld-type analysis. Appropriate annealing was performed in order to enable the ε-τ phase transformation. While hcp ε-phase was found to be predominant in the as-cast samples, after appropriate annealing, the tetragonal τ-phase, the one that furnishes the relevant magnetic response, was found to be predominant with an abundance of about 90%. The data suggested a mechanism of hcp ε-phase decomposition controlled by the segregation towards the interfacial regions, having the rate of transformation governed by antiphase boundary diffusion processes. Magnetic measurements of annealed sample Mn(53)Al(45)C(2), consisting of predominant tetragonal τ-phase, showed high values of magnetization and increased coercivity, consistent with an energy product of about 10 MGOe, similar with previously reported magnetization measurements, providing further insight into the realization of future class of RE-free low-cost permanent magnets.
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spelling pubmed-80657362021-04-25 Magnetism and ε-τ Phase Transformation in MnAl-Based Nanocomposite Magnets Crisan, Alina Daniela Leca, Aurel Bartha, Cristina Dan, Ioan Crisan, Ovidiu Nanomaterials (Basel) Article Melt spun ribbons of Mn(53)Al(45)C(2) and Mn(52)Al(46)C(2) have been synthesized by rapid quenching of the melt with the purpose of monitoring the ε-τ phase transformation to show technologically feasible ways to increase magnetic parameters and to illustrate the viability of these alloys as the next generation of rare earth (RE)-free magnets. By differential scanning calorimetry (DSC), activation energies and temperatures of onset of the ε-τ phase transformation were obtained. Structural analysis was performed using X-ray diffraction (XRD) and the resulting XRD patterns were quantitatively assessed using full profile Rietveld-type analysis. Appropriate annealing was performed in order to enable the ε-τ phase transformation. While hcp ε-phase was found to be predominant in the as-cast samples, after appropriate annealing, the tetragonal τ-phase, the one that furnishes the relevant magnetic response, was found to be predominant with an abundance of about 90%. The data suggested a mechanism of hcp ε-phase decomposition controlled by the segregation towards the interfacial regions, having the rate of transformation governed by antiphase boundary diffusion processes. Magnetic measurements of annealed sample Mn(53)Al(45)C(2), consisting of predominant tetragonal τ-phase, showed high values of magnetization and increased coercivity, consistent with an energy product of about 10 MGOe, similar with previously reported magnetization measurements, providing further insight into the realization of future class of RE-free low-cost permanent magnets. MDPI 2021-03-31 /pmc/articles/PMC8065736/ /pubmed/33807428 http://dx.doi.org/10.3390/nano11040896 Text en © 2021 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
Crisan, Alina Daniela
Leca, Aurel
Bartha, Cristina
Dan, Ioan
Crisan, Ovidiu
Magnetism and ε-τ Phase Transformation in MnAl-Based Nanocomposite Magnets
title Magnetism and ε-τ Phase Transformation in MnAl-Based Nanocomposite Magnets
title_full Magnetism and ε-τ Phase Transformation in MnAl-Based Nanocomposite Magnets
title_fullStr Magnetism and ε-τ Phase Transformation in MnAl-Based Nanocomposite Magnets
title_full_unstemmed Magnetism and ε-τ Phase Transformation in MnAl-Based Nanocomposite Magnets
title_short Magnetism and ε-τ Phase Transformation in MnAl-Based Nanocomposite Magnets
title_sort magnetism and ε-τ phase transformation in mnal-based nanocomposite magnets
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8065736/
https://www.ncbi.nlm.nih.gov/pubmed/33807428
http://dx.doi.org/10.3390/nano11040896
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