In situ TEM study of deformation twinning in Ni–Mn–Ga non-modulated martensite

Zárubová, N.; Ge, Yanling; Heczko, Oleg; Hannula, Simo‐Pekka

doi:10.1016/j.actamat.2013.05.020

Cited by 51 publications

(43 citation statements)

References 45 publications

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“…3c). This is consistent with the literature, where it is found that microstructure reorientation during loading initiates with first detwinning of internal twins [27,36]. It is also evident from EBSD measurement that larger plates more favourably oriented with respect to the applied load grow at the expense of the less favourably oriented ones as is also visible from the misorientation angle profile (Fig.…”

Section: Resultssupporting

confidence: 80%

“…It is seen that the more favourably oriented variant nucleates and grows consuming the less favourably oriented one. It is found by other researchers that detwinning process proceeds via the movement of twinning dislocations advancing on successive twin planes and converting one variant into another [36,37]. The expanding twin advances into the matrix with a characteristic tip due to a possible dislocation pile up (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Self-accommodated and pre-strained martensitic microstructure in single-crystalline, metamagnetic Ni–Mn–Sn Heusler alloy

et al. 2017

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Metamagnetic shape memory alloys are a unique class of materials capable of large magnetic field-induced strain due to reverse martensitic phase transformation. A precondition for large shape change is martensite deformation, which heavily depends on microstructure. Elucidation of microstructure is therefore indispensable for strain control and deformation mechanics in such systems. The current paper reports on a self-accommodated martensitic microstructure in metamagnetic Ni 50 Mn 37.5 Sn 12.5 single crystal. The microstructure here is hierarchically organised at three distinct levels. On a large scale, martensite plate colonies, distinguished by intercolony boundaries, group individual martensitic plates. Plates are separated by interplate boundaries and deviate by 2.2°from an ideal twin relation. On the lower scale, plates are composed of subplate twins. Conjugation boundaries separating two pairs of twins arise in relation to a subplate microstructure. Modulation boundaries separating two variants with perpendicular modulation directions and with parallel c-axes also appear. Mechanical training frees larger plates from fine subplate microtwins bringing macro-lamellae into twin relation, what then permits further detwinning until a single variant state.

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Section: Resultssupporting

confidence: 80%

Section: Resultsmentioning

confidence: 99%

Self-accommodated and pre-strained martensitic microstructure in single-crystalline, metamagnetic Ni–Mn–Sn Heusler alloy

et al. 2017

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“…However, the motion of twin boundary is not so simple because the activation energy of the shear induced coherent motion process is not of the same order of magnitude as the magnetocrystalline anisotropy energy which was shown by quasistatic DFT simulations [33,34]. The mechanism includes also twinning dislocations slip along the twinning interfaces, which was confirmed by an experimental transmission electron microscopy measurement [35][36][37]17] and also by DFT calculations in combination with the PeierlsNabarro model [32].…”

Section: Introductionmentioning

confidence: 48%

Ab initiostudy of Ni₂MnGa under shear deformation

Zelený

Straka

Sozinov

2015

MATEC Web of Conferences

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Abstract. The effect of shear deformation on Ni2MnGa magnetic shape memory alloy has been investigated using ab initio electronic structure calculations. We used the projector-augmented wave method for the calculations of total energies and stresses as functions of applied affine shear deformation. The studied nonmodulated martensite (NM) phase exhibits a tetragonally distorted L21 structure with c/a > 1. A large strain corresponding to simple shears in <100>{001}, <001>{100} and <010>{100} systems was applied to describe a full path between two equivalent NM lattices. We also studied <10-1>{101} shear which is related to twining of NM phase. Twin reorientation in this system is possible, because applied positive shear results in path with significantly smaller energetic barrier than for negative shear and for shears in other studied systems. When the full relaxation of lattice parameters is allowed, the barriers further strongly decrease and the structures along the twinning path can be considered as orthorhombic.

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“…Most importantly, the martensite plates in the lamellar structure are not twin related [14]. A consequence of this finding is that detwinning modes, responsible as has been lately shown for deformation of such a martensite structure [15,16], cannot change one martensite plate into another. Thus, deformation detwinning must take place within individual plates at a smaller length scale.…”

Section: Resultsmentioning

confidence: 71%

“…Recent in-situ straining of NM Ni-Mn-Ga shows that the deformation process in Ni-Mn-Ga alloys is governed by detwinning at the nanoscale level changing one region of nanotwins into another [14][15][16]. The full crystallographic description of deformation detwinning in Ni-Mn-Ga single crystals performed by means of the correspondence matrix method can be found in [20].…”

Section: Resultsmentioning

confidence: 99%

Non-Modulated Martensite Microstructure With Internal Nanotwins In Ni-Mn-Ga Alloys

Szczerba¹

2015

Archives of Metallurgy and Materials

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The self-accommodated non-modulated martensite of Ni-Mn-Ga single crystal was studied by transmission and scanning electron microscopy in the latter case using the electron backscatter diffraction technique. Three kinds of interfaces existing at different length scales were reported. The first, is the wavy and incoherent interface separating martensite variants observed on the micro-level with no-common crystallographic plane between them. The second is within a single martensite plate where the lattice rotates around one of the {110} pole to accommodate the interfacial curvature between martensite plates. Finally, at the nanoscale the third interface exists, a twin boundary separating internal nanotwins with the {112} type habit plane.Keywords: shape memory alloys; martensite; Ni-Mn-Ga single crystals; interface W pracy przeprowadzono obserwacje mikrostruktury monokryształu Ni-Mn-Ga charakteryzujący się nie-modulowaną strukturą martenzytyczną. Badania przeprowadzono z wykorzystaniem techniki transmisyjnej oraz skaningowej mikroskopii elektronowej. W przypadku drugiej metody zastosowano technikę elektronów wstecznie rozproszonych. Trzy rodzaje granic zostały zaobserwowane oraz opisane. Pierwsza granica jest niekoherentna i występuje w skali mikro pomiędzy płytkami martenzytu, które nie posiadają wspólnej płaszczyzny krystalograficznej o niskich indeksach Millera. Kolejna granica występuje wewnątrz pojedynczej płytki martenzytycznej, której towarzyszy rotacja sieci krystalicznej wokół kierunku {110} obszarów przedzielonych tą granicą w celu akomodacji wygięć granicy występującej między płytkami. W skali nanometrycznej można zaobserwować kolejną granicę równoległą do płaszczyzny krystalograficznej {112} (płaszczyzna bliźniacza), która rozdziela płytki nanobliźniaków.

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In situ TEM study of deformation twinning in Ni–Mn–Ga non-modulated martensite

Cited by 51 publications

References 45 publications

Self-accommodated and pre-strained martensitic microstructure in single-crystalline, metamagnetic Ni–Mn–Sn Heusler alloy

Self-accommodated and pre-strained martensitic microstructure in single-crystalline, metamagnetic Ni–Mn–Sn Heusler alloy

Ab initiostudy of Ni₂MnGa under shear deformation

Non-Modulated Martensite Microstructure With Internal Nanotwins In Ni-Mn-Ga Alloys

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In situ TEM study of deformation twinning in Ni–Mn–Ga non-modulated martensite

Cited by 51 publications

References 45 publications

Self-accommodated and pre-strained martensitic microstructure in single-crystalline, metamagnetic Ni–Mn–Sn Heusler alloy

Self-accommodated and pre-strained martensitic microstructure in single-crystalline, metamagnetic Ni–Mn–Sn Heusler alloy

Ab initiostudy of Ni2MnGa under shear deformation

Non-Modulated Martensite Microstructure With Internal Nanotwins In Ni-Mn-Ga Alloys

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Ab initiostudy of Ni₂MnGa under shear deformation