Jia, Yuxiao ; Ding, Hanlin ; Wu, Yuye ; Wang, Jingmin ; Wu, Haichen ; Ma, Tianyu ; Zhao, Shiteng ; Skokov, Konstantin P. ; Aubert, Alex ; Maccari, Fernando ; Gutfleisch, Oliver ; Xu, Yichen ; Niu, Jiejue ; Qiao, Boying ; Zhao, Shuang ; Jiang, Chengbao (2022)
On the ε → τ phase transformation and twinning in L10−MnAl alloys.
In: Acta Materialia, 232
doi: 10.1016/j.actamat.2022.117892
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
Formation of twins have been recognized as the bottleneck that limit the high-performance of L10-type Mn-Al permanent magnets. Although it is known that twinning occurs as a consequence of ε → τ phase transition, the detailed formation mechanism is still unclear. We studied systematically the phase transformation processes of ε → τ by transmission electron microscopy. The two-step transformation includes first a diffusion-controlled ordering transformation from disordered A3-type ε-phase to ordered B19-type ε’-variants, and second, a shearing transformation from ε’-phase to L10-type τ-phase via the stepwise atomic displacement with the vector of x/3<100>ε’. The two τ-variants generated from the same ε’-variant constitute the true twins with included angle of ∼76° The combination of τ-variants which are generated from different ε’-variant produces the order twins and pseudo twins with the included angles of ∼85° and ∼48°, respectively. The effects of true twins and order twins on coercivity are compared by studying the domain structures during demagnetization. The order-twin boundary has a more significantly effect on promoting the nucleation and propagation of the reversal domain, giving rise to a severer degradation effect on coercivity compared with true-twin boundary. The combination of directional solidification and hot-deformation is identified to effectively manipulate the ε → τ phase transition based on the proposed mechanism, as demonstrated by good magnetic properties of ∼400 mT in coercivity and ∼0.67 in remanence ratio in L10−MnAl magnets. Our work explains the mechanism on the formation of various twins in L10−MnAl, and offers guidelines of fabricating high-performance twins-containing MnAl permanent magnets.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2022 |
| Autor(en): | Jia, Yuxiao ; Ding, Hanlin ; Wu, Yuye ; Wang, Jingmin ; Wu, Haichen ; Ma, Tianyu ; Zhao, Shiteng ; Skokov, Konstantin P. ; Aubert, Alex ; Maccari, Fernando ; Gutfleisch, Oliver ; Xu, Yichen ; Niu, Jiejue ; Qiao, Boying ; Zhao, Shuang ; Jiang, Chengbao |
| Art des Eintrags: | Bibliographie |
| Titel: | On the ε → τ phase transformation and twinning in L10−MnAl alloys |
| Sprache: | Englisch |
| Publikationsjahr: | 14 April 2022 |
| Verlag: | Elsevier |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | Acta Materialia |
| Jahrgang/Volume einer Zeitschrift: | 232 |
| DOI: | 10.1016/j.actamat.2022.117892 |
| Kurzbeschreibung (Abstract): | Formation of twins have been recognized as the bottleneck that limit the high-performance of L10-type Mn-Al permanent magnets. Although it is known that twinning occurs as a consequence of ε → τ phase transition, the detailed formation mechanism is still unclear. We studied systematically the phase transformation processes of ε → τ by transmission electron microscopy. The two-step transformation includes first a diffusion-controlled ordering transformation from disordered A3-type ε-phase to ordered B19-type ε’-variants, and second, a shearing transformation from ε’-phase to L10-type τ-phase via the stepwise atomic displacement with the vector of x/3<100>ε’. The two τ-variants generated from the same ε’-variant constitute the true twins with included angle of ∼76° The combination of τ-variants which are generated from different ε’-variant produces the order twins and pseudo twins with the included angles of ∼85° and ∼48°, respectively. The effects of true twins and order twins on coercivity are compared by studying the domain structures during demagnetization. The order-twin boundary has a more significantly effect on promoting the nucleation and propagation of the reversal domain, giving rise to a severer degradation effect on coercivity compared with true-twin boundary. The combination of directional solidification and hot-deformation is identified to effectively manipulate the ε → τ phase transition based on the proposed mechanism, as demonstrated by good magnetic properties of ∼400 mT in coercivity and ∼0.67 in remanence ratio in L10−MnAl magnets. Our work explains the mechanism on the formation of various twins in L10−MnAl, and offers guidelines of fabricating high-performance twins-containing MnAl permanent magnets. |
| Freie Schlagworte: | MnAl permanent magnets, Twin structures, Solid-state phase transformation, Demagnetization process, Domain structure |
| Zusätzliche Informationen: | Paper No. 117892 |
| Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Funktionale Materialien |
| Hinterlegungsdatum: | 10 Aug 2022 07:23 |
| Letzte Änderung: | 10 Aug 2022 07:23 |
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