From crystallographic properties to macroscopic detwinning strain and magnetisation of Ni-Mn-Ga magnetic shape memory alloys

Hirsinger, Laurent; Creton, Nicolas; Lexcellent, Christian

doi:10.1051/jp4:2004115014

Cited by 11 publications

(16 citation statements)

References 1 publication

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“…These equalities lead to introduce a vector a r corresponding to the difference between the transformations of vector n r both side of the interface. We obtain then [2]:…”

Section: Physical Parametersmentioning

confidence: 99%

“…Boundaries between these domains are oriented 45° from the principal axes. 2 . We consider also that in U 3 O 7 the concentration of oxygen is constant and the chemical expansion coefficient can be neglected.…”

Section: Modelling Of a U 3 O 7 Layer On Uomentioning

confidence: 99%

“…In order to have a better understanding of mechanisms that govern the chemical fragmentation reaction related to the anionic oxidation of UO 2 we propose here to study the relations between mechanical stress and oxygen diffusion in a system composed of U 3 O 7 /UO 2 . This study need:…”

Section: Introductionmentioning

confidence: 99%

“…we consider that the move from the crystallographic lattice of the substrate to the oxide's one is realized, from a crystallographic point of view, through a homogeneous transformation between the initial (substrate) and deformed (oxide) configurations. Two methods are used and compared: -a first method giving, if it exists, the nature of the crystallographic compatibility at the interface (Hadamard condition [1], [2]), -a second one giving a good coincidence criterion between the crystallographic phases (Bollmann's method) allowing to know the relative orientation of the oxide regarding the substrate, but also the induced strain value necessary to arrange the crystallographic lattices (epitaxy strain).…”

Section: Introductionmentioning

confidence: 99%

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Internal Interface Strains Effects on UO2/U3O7 Oxidation Behaviour

Creton

Optasanu

Garruchet

et al. 2010

DDF

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Abstract. The growth of a U 3 O 7 oxide layer during the anionic oxidation of UO 2 pellets induced very important mechanical stresses due to the crystallographic lattice parameters differences between UO 2 and its oxide. These stresses, combined with the chemical processes of oxidation, can lead to the cracking of the system, called chemical fragmentation. We study the crystallographic orientation of the oxide lattice growing at the surface of UO 2 , pointing the fact that epitaxy relations at interface govern the coexistence of UO 2 and U 3 O 7 . In this work, several results are given:-Determination of the epitaxy relations between the substrate and its oxide thanks to the Bollmann's method; epitaxy strains are deduced.-Study of the coexistence of different domains in the U 3 O 7 (crystallographic compatibility conditions at the interface between two phases: Hadamard conditions).-FEM simulations of a multi-domain U 3 O 7 connected to a UO 2 substrate explain the existence of a critical thickness of U 3 O 7 layer.

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“…These equalities lead to introduce a vector a r corresponding to the difference between the transformations of vector n r both side of the interface. We obtain then [2]:…”

Section: Physical Parametersmentioning

confidence: 99%

Section: Modelling Of a U 3 O 7 Layer On Uomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Internal Interface Strains Effects on UO2/U3O7 Oxidation Behaviour

Creton

Optasanu

Garruchet

et al. 2010

DDF

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“…The most commonly investigated MSMA is NiMnGa, in which the 5M (five-layered modulated) martensite 24,25 consists of three tetragonal variants. If in the martensitic phase a uniaxial compressive stress and a perpendicular magnetic field are applied along the appropriate crystallographic directions, one variant is stress-favored, one magnetic field-favored and the third variant is eliminated.…”

Section: 23mentioning

confidence: 99%

Modeling of the Stress- and Magnetic Field-Induced Variant Reorientation in MSMAs

Lagoudas¹

2006

47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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This paper is concerned with the modeling of the magnetic shape memory alloy (MSMA) constitutive response caused by the reorientation of martensitic variants. Following a summary of the constitutive model previously proposed by the authors, the nonlinear and hysteretic strain and magnetization response of MSMAs are investigated for two main loading cases, namely the magnetic field-induced reorientation of variants under constant uniaxial stress and the stress-induced reorientation under constant magnetic field. It is demonstrated in this work that the model captures the loading history dependence of the constitutive behavior through the evolution of internal state variables. Complex loading cases are also presented in which the sequence of the application of the stress and magnetic field strongly influences the predicted response. The relation of critical stresses and magnetic fields for the activation of the reorientation process are visualized in a variant reorientation diagram on which the considered loading paths are superimposed.

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Modelling of magneto‐mechanical hysteresis loops in Ni‐Mn‐Ga shape memory alloys
Hirsinger
¹

2004
phys. stat. sol. (c)
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PACS 75.50Cc, 75.60.Ch, 75.60.Ej, 75.80.+q A predictive model of field-induced strain in Ni-Mn-Ga ferromagnetic shape memory alloys is proposed. In this study, magnetocrystalline anisotropy K 1 is introduced to permit magnetisation rotation in martensite platelets. The demagnetisation field induced by the shape of platelets is investigated. The proposed model is identified on experiments performed by Straka et al. This identification shows that observed macroscopic hysteresis loops, i.e. magnetisation and detwinning strain versus applied magnetic field, correspond exactly to a successive activation of three mechanisms: Movement of 180° domain walls, rotation of magnetisation and martensite detwinning. As expected, magnetization and strain -induced by magnetic field-in a single crystal are mainly given by the mobility of twin boundaries and magnetic anisotropies (due to the martensite crystallographic structure and to the shape of platelets).

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From crystallographic properties to macroscopic detwinning strain and magnetisation of Ni-Mn-Ga magnetic shape memory alloys

Cited by 11 publications

References 1 publication

Internal Interface Strains Effects on UO<sub>2</sub>/U<sub>3</sub>O<sub>7</sub> Oxidation Behaviour

Internal Interface Strains Effects on UO<sub>2</sub>/U<sub>3</sub>O<sub>7</sub> Oxidation Behaviour

Modeling of the Stress- and Magnetic Field-Induced Variant Reorientation in MSMAs

Modelling of magneto‐mechanical hysteresis loops in Ni‐Mn‐Ga shape memory alloys

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