Duality of Wave Modulation and Nanotwinning in Ni-Mn-Ga Martensite via Long-Period Commensurate States
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| Main Authors: | , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| author | Veřtát, P. Zelený, M. Sozinov, A. Klicpera, M. Fabelo, O. Chulist, R. Vinogradova, M. Sedlák, P. Seiner, H. Heczko, O. Straka, L. |
| author_facet | Veřtát, P. Zelený, M. Sozinov, A. Klicpera, M. Fabelo, O. Chulist, R. Vinogradova, M. Sedlák, P. Seiner, H. Heczko, O. Straka, L. |
| contents | Structural modulation is a key ingredient behind the extraordinary (magneto)elastic response of Ni-Mn-Ga martensite, yet its link to fine twinned microstructure and twin-boundary supermobility remains unresolved. Here we analyse martensitic single crystals of Ni50.0Mn27.7Ga22.3 and Ni50.0Mn28.1Ga21.9. Neutron and X-ray diffraction reveal an anharmonic five-layer structural modulation--as evidenced by high-order satellite reflections--that evolves from commensurate (q = 2/5) to incommensurate (2/5 < q < 5/12) upon cooling. Interpreting the refined modulation displacements in terms of a basal-plane stacking sequence provides a structural link between the wave description and the microstructure that develops on cooling. In this view, the evolving incommensurability produces periodic nanodomains that we assign to emerging a/b-nanotwins with size ~20 nm at ~290 K. With further cooling, the modulation can lock into long-period commensurate states (e.g., 24O, 34O, and 14O), whose orthorhombic unit cells can also be viewed as a/b-nanotwins. Ab initio calculations show that these long-period structures are energetically competitive with 10M structure, in line with the experimentally observed lock-in transition to 24O in the alloys studied and to 14O in Ni50Mn25Ga25 (stoichiometric Ni2MnGa). Together, these results clarify how the evolving modulation can be interpreted in terms of a/b-nanotwins and long-period commensurate lock-ins, linking the wave-modulation and nanotwinning descriptions within a single structural framework. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2503_04379 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Duality of Wave Modulation and Nanotwinning in Ni-Mn-Ga Martensite via Long-Period Commensurate States Veřtát, P. Zelený, M. Sozinov, A. Klicpera, M. Fabelo, O. Chulist, R. Vinogradova, M. Sedlák, P. Seiner, H. Heczko, O. Straka, L. Materials Science Structural modulation is a key ingredient behind the extraordinary (magneto)elastic response of Ni-Mn-Ga martensite, yet its link to fine twinned microstructure and twin-boundary supermobility remains unresolved. Here we analyse martensitic single crystals of Ni50.0Mn27.7Ga22.3 and Ni50.0Mn28.1Ga21.9. Neutron and X-ray diffraction reveal an anharmonic five-layer structural modulation--as evidenced by high-order satellite reflections--that evolves from commensurate (q = 2/5) to incommensurate (2/5 < q < 5/12) upon cooling. Interpreting the refined modulation displacements in terms of a basal-plane stacking sequence provides a structural link between the wave description and the microstructure that develops on cooling. In this view, the evolving incommensurability produces periodic nanodomains that we assign to emerging a/b-nanotwins with size ~20 nm at ~290 K. With further cooling, the modulation can lock into long-period commensurate states (e.g., 24O, 34O, and 14O), whose orthorhombic unit cells can also be viewed as a/b-nanotwins. Ab initio calculations show that these long-period structures are energetically competitive with 10M structure, in line with the experimentally observed lock-in transition to 24O in the alloys studied and to 14O in Ni50Mn25Ga25 (stoichiometric Ni2MnGa). Together, these results clarify how the evolving modulation can be interpreted in terms of a/b-nanotwins and long-period commensurate lock-ins, linking the wave-modulation and nanotwinning descriptions within a single structural framework. |
| title | Duality of Wave Modulation and Nanotwinning in Ni-Mn-Ga Martensite via Long-Period Commensurate States |
| topic | Materials Science |
| url | https://arxiv.org/abs/2503.04379 |