Kinetics of Reordering in Quenched Ni<sub>2</sub>Mn<sub>0.8</sub>Cu<sub>0.2</sub>Ga Ferromagnetic Shape Memory Alloys
Quenched Ni<sub>2</sub>Mn<sub>1−<i>x</i></sub>Cu<i><sub>x</sub></i>Ga ferromagnetic shape memory alloys undergo two consecutive post-quench ordering processes. The kinetics of order recovery has been analysed in detail for Ni<sub>2<...
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MDPI AG
2022-04-01
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| Series: | Metals |
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| Online Access: | https://www.mdpi.com/2075-4701/12/5/738 |
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| author | Concepció Seguí |
| author_facet | Concepció Seguí |
| author_sort | Concepció Seguí |
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| description | Quenched Ni<sub>2</sub>Mn<sub>1−<i>x</i></sub>Cu<i><sub>x</sub></i>Ga ferromagnetic shape memory alloys undergo two consecutive post-quench ordering processes. The kinetics of order recovery has been analysed in detail for Ni<sub>2</sub>Mn<sub>0.8</sub>Cu<sub>0.2</sub>Ga, based on the calorimetric curves obtained during post-quench heating at constant rates. Isoconversional methods have been used to determine the activation energy, the pre-exponential factor, and the reaction model that best fits the two reordering processes. The kinetic analysis has been extended to samples quenched from different temperatures. The kinetic study shows that order improvement processes in quenched Ni<sub>2</sub>Mn<sub>0.8</sub>Cu<sub>0.2</sub>Ga alloys can be described by a first order reaction model, consistent with site-saturation nucleation and homogeneous diffusion-controlled growth, with apparent activation energies around 1.1 eV. The pre-exponential factors, especially those obtained for samples quenched from different temperatures, highlight the crucial role of the vacancies retained by high temperature quenching on the atomic reordering underlying the observed processes. |
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| language | English |
| last_indexed | 2024-03-10T03:25:47Z |
| publishDate | 2022-04-01 |
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| spelling | doaj.art-231905893fd846c49661cd2667289d022023-11-23T12:08:35ZengMDPI AGMetals2075-47012022-04-0112573810.3390/met12050738Kinetics of Reordering in Quenched Ni<sub>2</sub>Mn<sub>0.8</sub>Cu<sub>0.2</sub>Ga Ferromagnetic Shape Memory AlloysConcepció Seguí0Departament de Física, Universitat de les Illes Balears, Campus Cra. Valldemossa, km 7.5, 07122 Palma, SpainQuenched Ni<sub>2</sub>Mn<sub>1−<i>x</i></sub>Cu<i><sub>x</sub></i>Ga ferromagnetic shape memory alloys undergo two consecutive post-quench ordering processes. The kinetics of order recovery has been analysed in detail for Ni<sub>2</sub>Mn<sub>0.8</sub>Cu<sub>0.2</sub>Ga, based on the calorimetric curves obtained during post-quench heating at constant rates. Isoconversional methods have been used to determine the activation energy, the pre-exponential factor, and the reaction model that best fits the two reordering processes. The kinetic analysis has been extended to samples quenched from different temperatures. The kinetic study shows that order improvement processes in quenched Ni<sub>2</sub>Mn<sub>0.8</sub>Cu<sub>0.2</sub>Ga alloys can be described by a first order reaction model, consistent with site-saturation nucleation and homogeneous diffusion-controlled growth, with apparent activation energies around 1.1 eV. The pre-exponential factors, especially those obtained for samples quenched from different temperatures, highlight the crucial role of the vacancies retained by high temperature quenching on the atomic reordering underlying the observed processes.https://www.mdpi.com/2075-4701/12/5/738ferromagnetic shape memory alloysNi<sub>2</sub>MnGaatomic orderingkineticsvacancies |
| spellingShingle | Concepció Seguí Kinetics of Reordering in Quenched Ni<sub>2</sub>Mn<sub>0.8</sub>Cu<sub>0.2</sub>Ga Ferromagnetic Shape Memory Alloys Metals ferromagnetic shape memory alloys Ni<sub>2</sub>MnGa atomic ordering kinetics vacancies |
| title | Kinetics of Reordering in Quenched Ni<sub>2</sub>Mn<sub>0.8</sub>Cu<sub>0.2</sub>Ga Ferromagnetic Shape Memory Alloys |
| title_full | Kinetics of Reordering in Quenched Ni<sub>2</sub>Mn<sub>0.8</sub>Cu<sub>0.2</sub>Ga Ferromagnetic Shape Memory Alloys |
| title_fullStr | Kinetics of Reordering in Quenched Ni<sub>2</sub>Mn<sub>0.8</sub>Cu<sub>0.2</sub>Ga Ferromagnetic Shape Memory Alloys |
| title_full_unstemmed | Kinetics of Reordering in Quenched Ni<sub>2</sub>Mn<sub>0.8</sub>Cu<sub>0.2</sub>Ga Ferromagnetic Shape Memory Alloys |
| title_short | Kinetics of Reordering in Quenched Ni<sub>2</sub>Mn<sub>0.8</sub>Cu<sub>0.2</sub>Ga Ferromagnetic Shape Memory Alloys |
| title_sort | kinetics of reordering in quenched ni sub 2 sub mn sub 0 8 sub cu sub 0 2 sub ga ferromagnetic shape memory alloys |
| topic | ferromagnetic shape memory alloys Ni<sub>2</sub>MnGa atomic ordering kinetics vacancies |
| url | https://www.mdpi.com/2075-4701/12/5/738 |
| work_keys_str_mv | AT concepciosegui kineticsofreorderinginquenchednisub2submnsub08subcusub02subgaferromagneticshapememoryalloys |