Highly mobile twin boundaries in seven-layer modulated Ni-Mn-Ga-Fe martensite
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We report on low twinning stress of 0.2 MPa for type 1 twin boundaries with rational (101) twinning plane and 0.1 MPa for type 2 twin boundaries with rational [(1) over bar 01] twinning direction, in Ni2MnGa0.8Fe0.2 seven-layer modulated martensite exhibiting about 12% stress-induced strain. The studied samples were free of compound twins with (100) and (110) twinning planes. The martensite lattice is monoclinic and shows a long-period commensurate modulation with wave vector q=(2/7)g(110), where g(110) is the reciprocal lattice vector. The investigated alloy has high potential for practical applications due to the low twinning stress and the elevated Curie point T-C=400 K. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd.
KeywordsMagnetic shape memory, Martensite, Twin boundary, Ni-Mn-Ga, Heusler alloy
Document typePeer reviewed
Document versionFinal PDF
SourceSCRIPTA MATERIALIA. 2020, vol. 178, issue 1, p. 62-66.