Compressive response of a single crystalline CoNiAl shape memory alloy

KARACA, H

doi:10.1016/s1359-6462(04)00215-5

Cited by 2 publications

(2 citation statements)

References 11 publications

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“…Extensive experimental work on off-stoichiometric intermetallic compounds near the composition Ni 2 MnGa have yielded of up to 10% in single crystals. 5 Additional alloys have been investigated, such as FePd 6,7 and CoNiAL, 8 among others. Under the influence of temperature and stress fields, MSMAs also exhibit conventional shape memory and pseudoelastic behavior.…”

Section: Magnetic Shape Memory Alloys and Their Applicationsmentioning

confidence: 99%

Modeling of the magnetic field-induced martensitic variant reorientation and the associated magnetic shape memory effect in MSMAs

Kiefer

Lagoudas

2005

SPIE Proceedings

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This work is concerned with the magnetic field-induced rearrangement of martensitic variants in magnetic shape memory alloys (MSMAs). In addition to the variant reorientation, the rotation of the magnetization and magnetic domain wall motion are considered as the microstructural mechanisms causing the macroscopically observable constitutive response. The considered free energy terms are the elastic strain energy, the Zeeman energy and the magnetocrystalline anisotropy energy. It is shown how thermodynamic constraints on the magnetization rotation lead to only partial reorientation of the martensitic variants under higher stresses. A straightforward methodology has been devised for the calibration of model parameters based on experimental data. The presented model predictions indicate an improvement of the predictability of the nonlinear strain hysteresis and in particular the magnetization hysteresis.Keywords: magnetic shape memory alloys, ferromagnetic shape memory effect, magnetic field induced strain, martensitic variant reorientation, magnetic hysteresis. MAGNETIC SHAPE MEMORY ALLOYS AND THEIR APPLICATIONSMagnetic shape memory alloys have been considered as alternative actuator materials to be used for applications not suitable for conventional shape memory alloys (SMAs). The high mobility of twin boundaries in the martensitic phase of MSMAs allows for high frequency magnetic actuation. Furthermore, because the deformation of the MSMA material is magnetic-field controlled, the actuation can in principle be initiated in a contact-free manner. A first generation of such actuators have been designed and built and are presently commercially available. 1-3Magnetic shape memory alloys (MSMAs) have intensely been researched since the first studies of their behavior were reported by Ullakko et al. (1996). 4 They found magnetic field-induced trains of nearly 0.2% in stress-free experiments on martensitic NiMnGa single crystals. Extensive experimental work on off-stoichiometric intermetallic compounds near the composition Ni 2 MnGa have yielded of up to 10% in single crystals. 5 Additional alloys have been investigated, such as FePd 6, 7 and CoNiAL, 8 among others. Under the influence of temperature and stress fields, MSMAs also exhibit conventional shape memory and pseudoelastic behavior.The magnetic field-induced rearrangement of martensitic variants and the associated actuation of large inelastic strains has been termed the magnetic shape memory effect (MSME). The process occurs because each of the variants possesses different preferred directions of magnetization, called magnetic easy axes. That way those variants that are more favorably oriented with respect to an externally applied magnetic field can be selected over other less favorably oriented ones, resulting in the observed macroscopic shape change. The field-induced deformation of the material is accompanied by a nonlinear change in its magnetization, a process which will be discussed in more detail in the following section. The phenomenological constitutive...

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Section: Magnetic Shape Memory Alloys and Their Applicationsmentioning

confidence: 99%

Modeling of the magnetic field-induced martensitic variant reorientation and the associated magnetic shape memory effect in MSMAs

Kiefer

Lagoudas

2005

SPIE Proceedings

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“…2 Other alloys have been investigated, such as FePd, 3,4 FeNiCoTi 5 and CoNiAL. 6 In addition to the large recoverable strains, which are caused by the field-driven reorientation of martensitic variants, magnetic shape memory alloys are characterized by the nonlinear and hysteretic nature of their response, as well as the coupling of the shape change and the nonlinear change in the magnetization.…”

Section: Introductionmentioning

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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Compressive response of a single crystalline CoNiAl shape memory alloy

Cited by 2 publications

References 11 publications

Modeling of the magnetic field-induced martensitic variant reorientation and the associated magnetic shape memory effect in MSMAs

Modeling of the magnetic field-induced martensitic variant reorientation and the associated magnetic shape memory effect in MSMAs

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

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