Journal ArticleDOI
Giant magnetic-field-induced strain in NiMnGa seven-layered martensitic phase
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TLDR
In this paper, a magnetic-field-induced strain of about 9.5% was observed at ambient temperature in a magnetic field of less than 1 T in NiMnGa orthorhombic seven-layered martensitic phase.Abstract:
Giant magnetic-field-induced strain of about 9.5% was observed at ambient temperature in a magnetic field of less than 1 T in NiMnGa orthorhombic seven-layered martensitic phase. The strain proved to be caused by magnetic-field-controlled twin boundary motion. According to an analysis of x-ray diffraction data, the crystal structure of this phase is nearly orthorhombic, having lattice parameters a=0.619 nm, b=0.580 nm, and c=0.553 nm (in cubic parent phase coordinates) at ambient temperature. Seven-layer shuffling-type modulation along the (110)[110]p system was recorded. The results of mechanical tests and magnetic anisotropy property measurements are also reported.read more
Citations
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Journal ArticleDOI
Modeling and parametric studies of magnetic shape memory alloy–based energy harvester:
TL;DR: In this paper, a model to simulate the behavior of a magnetic shape memory alloy while harvesting vibratory energy was presented, and the model was applied to a vibrational energy harvester.
Proceedings ArticleDOI
Characterization of piezoelectrically induced actuation of Ni-Mn-Ga single crystals
TL;DR: In this paper, an actuation method for shape memory alloys in the martensitic phase is described, in which asymmetric acoustic pulses are used to drive twin boundary motion.
Dissertation
Magneto-mechanical behavoirs of ferromagnetic shape memory alloys
Xue Chen,Ziad Moumni,Yongjun He +2 more
Abstract: Ferromagnetic Shape Memory Alloys (FSMA) are promising candidates for sensors and actuators for their high-frequency response and large reversible strain. The aim of this dissertation is the analysis of the magneto-mechanical behaviors of FSMA. In this aim, we study, both experimentally and theoretically, the martensite reorientation in FSMA. Firstly, a 2D/3D magneto-mechanical energy analysis is proposed and incorporated into phase diagrams for a graphic study of path-dependent martensite reorientation in FSMA under 3D loadings. Criteria and material requirements for obtaining reversible strain in cyclic loadings are derived. The energy analysis predicts that FSMA in 2D/3D configurations (multi-axial stresses) has much more advantages than in 1D configuration, e.g., higher output stress and more application flexibility. Secondly, to validate the predictions of the energy analysis, 2D experiments are performed on FSMA and results reveal that the intrinsic dissipation and the transformation strain due to martensite reorientation are constant in all tested 2D stress states. Moreover, preliminary results validate that the output stress of FSMA in 2D configuration (magnetic field with biaxial stresses) is larger than in 1D configuration, and the output stress can be increased by increasing the auxiliary stress. Finally, to predict the magneto-mechanical behaviors of FSMA in general multi-axial loadings, a 3D constitutive model is developed within the framework of thermodynamics of irreversible processes. All the martensite variants are considered and the temperature effect is also taken into account. Model simulations agree well with all the existing 1D/2D experiments. The model is further incorporated into finite element analysis for studying the non-linear bending behaviors of FSMA beams. The sample-geometry effect and the material anisotropic effect are systematically investigated.
Effect of Co on the martensitic transformation, crystal structure and magnetization of Ni52.5Mn23.5Ga24 based ferromagnetic shape memory alloys
TL;DR: In this article, the martensitic label was used to distinguish between martenitic and non-martensitic types of fire ants, and the number of fires was increased.
Journal ArticleDOI
Tailoring damping properties by electron irradiation in Ni-Mn-Ga shape memory alloys in a wide high-temperature range
TL;DR: In this article, a new method to obtain high damping Ni54Mn25Ga21 alloy with a wide high-temperature range was proposed. But the effect of dislocations on the interaction between interstitials and twin boundaries was not considered.
References
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Journal ArticleDOI
Large magnetic‐field‐induced strains in Ni2MnGa single crystals
TL;DR: In this paper, the superelastic motion of twin boundaries in the martensitic phase of Ni2MnGa with magnetic fields of 8 kOe applied at 265 K was found to be associated with the staining.
Journal ArticleDOI
6% magnetic-field-induced strain by twin-boundary motion in ferromagnetic Ni–Mn–Ga
TL;DR: In this paper, a simple model accounts quantitatively for the dependence of strain on magnetic field and external stress using as input parameters only measured quantities, and the strain versus field curves exhibit appreciable hysteresis associated with the motion of the twin boundaries.
Journal ArticleDOI
Magnetostriction of martensite
Richard D. James,Manfred Wuttig +1 more
TL;DR: In this article, a general strategy for inducing magnetostriction in ferromagnetic martensitic materials is described, and an analysis of domain redistribution caused by a magnetic field is given.
Journal ArticleDOI
Model for strain and magnetization in magnetic shape-memory alloys
TL;DR: In this paper, a simple phenomenological model for the magnetization process and field-induced strain by twin-boundary and phaseboundary motion is proposed for both the strong and weak anisotropy cases.
Journal ArticleDOI
Crystal structure of martensitic phases in Ni–Mn–Ga shape memory alloys
TL;DR: The crystal structures of the different martensitic phases observed in a wide variety of Ni-Mn-Ga alloy compositions have been studied in detail as discussed by the authors, and two approaches taken from the literature are analysed and discussed.