Double twinning in Ni–Mn–Ga–Co

Rolfs, Katharina; Chmielus, Markus; Wimpory, Robert C.; Mecklenburg, A.; Müllner, Peter; Schneider, R.

doi:10.1016/j.actamat.2009.12.051

Cited by 20 publications

(12 citation statements)

References 25 publications

(26 reference statements)

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“…This indicates that the high mobility of the interfaces may not be directly related to the modulations or to the crystal structure. This is also in agreement with the fact that while a Ni-Mn-Ga-Co alloy (4.9 at.% of Co) with very similar structure and lattice parameters as 14 M Ni-Mn-Ga exhibits a conventionally high twinning stress [18] (reorientation under 25 MPa), the 14 M martensite of Ni-Fe-Ga-Co alloy has a low twinning stress of approximately 1 MPa [19].…”

Section: Comparison With Other Smassupporting

confidence: 70%

Highly mobile interfaces in shape memory alloys

Seiner

2015

MATEC Web of Conferences

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Abstract. Macro-twin interfaces in single crystals of 10 M modulated Ni-Mn-Ga martensite have recently attracted a lot of attention due to the extraordinarily low twinning stress required to set them into motion; depending on the particular twinning mode, this stress can range between 0.05 and 1 MPa, and can be either strongly temperature dependent, or nearly temperature independent. The understanding to these effects is still not satisfactory, mainly due to the high complexity of these interfaces at the micro-scale (higher-order lamination) as well as at the atomistic scale (modulations of martensite). This paper brings a brief review of the recent experimental and theoretical achievements related to these highly mobile interfaces. The uniqueness of the behavior of 10 M martensite is shown by its comparison with other shape memory alloys with relatively low twinning stresses; then, this behavior is discussed in terms of its temperature dependence, strain rate dependence and the effect of the micromorphology of the interfaces.

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Section: Comparison With Other Smassupporting

confidence: 70%

Highly mobile interfaces in shape memory alloys

Seiner

2015

MATEC Web of Conferences

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“…Considerable strain deformation and large recovery ratio have been observed in polycrystalline Ni 53.5 Mn 26.0 Ga 20.5 alloy that crystallizes in 7 M monoclinic structure with magneto-structural transformation, owing to low residual stresses and multimode twinning [22]. Recent Electron Backscatter Diffraction (EBSD) studies report further insight into the orientation relations between twin variants in Ni 50 Mn 28 Many recent studies on quasi-ternary Ni-Mn-Ga-X alloys have been directed at the selective partial substitution of 3d elements, Co and Fe [6,[24][25][26][27][28]. Substitution of Co for Ni causes an increase Table 1 Chemical composition from EDAX, electron per atom ratio, martensitic start (Ms), martensitic finish (M f ), austenite start (As) and austenite finish (A f ), martensitic transformation temperature (TM = (Ms + M f + As + A f )/4) and Curie temperature (TC) of Co-doped alloys currently studied.…”

Section: Introductionmentioning

confidence: 99%

Effect of selective substitution of Co for Ni or Mn on the superstructure and microstructural properties of Ni50Mn29Ga21

Kumar¹,

Ramudu²,

Seshubai³

2011

Journal of Alloys and Compounds

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“…Later several distinct martensite structures were observed in NMGs: seven (14 M) modulated martensite [3,13], five (10 M) modulated martensite [14][15][16], nonmodulated martensite [17]. It was suggested that the shape memory effect is largely determined by the arrangement, type and movement of the twin boundaries (TBs) in NMG alloys [18][19][20][21][22]. The minimal stress needed to move a TB determines the critical twinning stress.…”

Section: Introductionmentioning

confidence: 97%

Multiscale twin hierarchy in NiMnGa shape memory alloys with Fe and Cu

Barabash

Popov

et al. 2015

Acta Materialia

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X-ray microdiffraction and scanning electron microscopy studies reveal 10 M martensitic structure with a highly correlated multiscale twin hierarchy organization in NiMnGaFeCu shape memory alloys. High compatibility is found at the twin interfaces resulting in a highly correlated twinned lattice orientation across several laminate levels. The lattice unit cell is described as monoclinic I-centered with a = 4.28 Å , b = 4.27 Å , c = 5.40 Å , c = 78.5°. The modulation is found parallel to the b axis. Thin tapered needle-like lamellae and branching are observed near the twin boundaries.

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Double twinning in Ni–Mn–Ga–Co

Cited by 20 publications

References 25 publications

Highly mobile interfaces in shape memory alloys

Highly mobile interfaces in shape memory alloys

Effect of selective substitution of Co for Ni or Mn on the superstructure and microstructural properties of Ni50Mn29Ga21

Multiscale twin hierarchy in NiMnGa shape memory alloys with Fe and Cu

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