Compliant Lattice Modulations Enable Anomalous Elasticity in Ni-Mn-Ga Martensite.

Autor: Repček K; Institute of Thermomechanics of the Czech Academy of Sciences, Prague 8, 18200, Czech Republic., Stoklasová P; Institute of Thermomechanics of the Czech Academy of Sciences, Prague 8, 18200, Czech Republic., Grabec T; Institute of Thermomechanics of the Czech Academy of Sciences, Prague 8, 18200, Czech Republic., Sedlák P; Institute of Thermomechanics of the Czech Academy of Sciences, Prague 8, 18200, Czech Republic., Olejňák J; Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague 2, 12000, Czech Republic., Vinogradova M; Material Physics Laboratory, Lappeenranta-Lahti University of Technology (LUT), Lappeenranta, 53850, Finland., Sozinov A; Material Physics Laboratory, Lappeenranta-Lahti University of Technology (LUT), Lappeenranta, 53850, Finland., Veřtát P; FZU - Institute of Physics of the Czech Academy of Sciences, Prague 8, 18200, Czech Republic., Straka L; FZU - Institute of Physics of the Czech Academy of Sciences, Prague 8, 18200, Czech Republic., Heczko O; FZU - Institute of Physics of the Czech Academy of Sciences, Prague 8, 18200, Czech Republic., Seiner H; Institute of Thermomechanics of the Czech Academy of Sciences, Prague 8, 18200, Czech Republic.
Jazyk: angličtina
Zdroj: Advanced materials (Deerfield Beach, Fla.) [Adv Mater] 2024 Sep; Vol. 36 (39), pp. e2406672. Date of Electronic Publication: 2024 Aug 12.
DOI: 10.1002/adma.202406672
Abstrakt: High mobility of twin boundaries in modulated martensites of Ni-Mn-Ga-based ferromagnetic shape memory alloys holds a promise for unique magnetomechanical applications. This feature has not been fully understood so far, and in particular, it has yet not been unveiled what makes the lattice mechanics of modulated Ni-Mn-Ga specifically different from other martensitic alloys. Here, results of dedicated laser-ultrasonic measurements on hierarchically twinned five-layer modulated (10M) crystals fill this gap. Using a combination of transient grating spectroscopy and laser-based resonant ultrasound spectroscopy, it is confirmed that there is a shear elastic instability in the lattice, being significantly stronger than in any other martensitic material and also than what the first-principles calculations for Ni-Mn-Ga predict. The experimental results reveal that the instability is directly related to the lattice modulations. A lattice-scale mechanism of dynamic faulting of the modulation sequence that explains this behavior is proposed; this mechanism can explain the extraordinary mobility of twin boundaries in 10M.
(© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)
Databáze: MEDLINE
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