Detail publikace

Duality of wave modulation and nanotwinning in Ni-Mn-Ga martensite via long-period commensurate states

VERTAT, P. ZELENÝ, M. SOZINOV, A. KLICPERA, M. FABELO, O. CHULIST, R. VINOGRADOVA, M. SEDLAK, P. SEINER, H. HECZKO, O. STRAKA, L.

Anglický název

Duality of wave modulation and nanotwinning in Ni-Mn-Ga martensite via long-period commensurate states

Typ

Článek WoS

Jazyk

en

Originální abstrakt

Structural modulation is a key ingredient behind the extraordinary (magneto)elastic response of Ni-Mn-Ga martensite, yet its link to fine microstructural features 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-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 as a basal-plane stacking sequence links the wave description to the microstructural evolution on cooling. In this view, evolving incommensurability produces periodic nanodomains interpreted as emerging a/b-nanotwins with a characteristic size of approximate to 20 nm at approximate to 290 K. With further cooling, the modulation can lock into long-period commensurate (LP-C) states, such as 34O (q = 7/17), 24O (q = 5/12), and 14O (q = 3/7), whose orthorhombic unit cells can be viewed as a/b-nanotwins. Ab initio calculations show that LP-C structures are energetically competitive with the initial commensurate state, supporting a shallow martensitic energy landscape. We propose a physical picture in which the martensitic transformation selects a commensurate state with q = 2/5 in the Mn-rich compositions studied here, while subsequent cooling drives relaxation within the martensitic landscape toward LP-C states, particularly 24O in the present alloys. The resulting structure is neither purely wave-like nor purely nanotwinned; rather, it reflects coupling between a coherent modulation wave and local accommodation via NM-like tetragonal distortions, nanotwinning, and LP-C lock-ins, providing a structural basis for the wave-nanotwin duality in Ni-Mn-Ga martensite.

Klíčová slova anglicky

Magnetic shape memory, Structural modulation, Long-period structure, Nanotwinning, Neutron diffraction

Vydáno

2026-09-15

Nakladatel

Elsevier

Časopis

Acta materialia

Ročník

317

Číslo

September

Strany od–do

122510–

Počet stran

18

BIBTEX


@article{BUT212200,
  author="{} and Martin {Zelený} and  {} and  {} and  {} and  {} and  {} and  {} and  {} and  {} and  {}",
  title="Duality of wave modulation and nanotwinning in Ni-Mn-Ga martensite via long-period commensurate states",
  journal="Acta materialia",
  year="2026",
  volume="317",
  number="September",
  pages="18",
  doi="10.1016/j.actamat.2026.122510",
  issn="1359-6454",
  url="https://www.sciencedirect.com/science/article/pii/S1359645426006117"
}