Investigation of the Interaction of Magnetic Field With the Auxetic Behavior of Galfenol

Raghunath, Ganesh; Flatau, Alison B.

doi:10.1109/tmag.2014.2322313

Cited by 4 publications

(13 citation statements)

References 22 publications

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“…The current work builds upon the results obtained in Ref. and adds insights based on results from density functional theory (DFT) simulations that corroborate the evidence for the magnetoelastic auxetic‐like behavior in these alloys, with negative strain ratio values of less than −1 at magnetic saturation. These simulations are used to provide greater insight into the atomic‐scale electronic mechanisms that are the origin of the magnetoelastic auxetic‐like response to an applied magnetic field in the BCC alloy being studied.…”

Section: Introductionsupporting

confidence: 67%

“…The experimental data presented in this paper are from our prior work . A description of the process used to grow the single crystal Galfenol samples is presented in those works, along with detailed descriptions of the experimental procedure and use of an electromagnet to apply a uniform, uniaxial magnetic field along the [110]{100} direction of single crystal Galfenol samples.…”

Section: Methodsmentioning

confidence: 99%

“…Here, at the reviewers’ suggestion, we call this behavior auxetic‐like rather than auxetic. In 2014, Raghunath and Flatau first reported that Galfenol exhibits a positive strain in both the longitudinal and transverse directions when a uniaxial magnetic force is applied to the sample by applying a uniaxial magnetic field along the ⟨110⟩{100} direction . The variation of this negative strain ratio (i.e., the ratio of transverse contraction strain to longitudinal extension strain) at magnetic saturation in response to a uniaxial magnetic force (i.e., the force on the sample from a uniaxial magnetic field) for a broad spectrum of Ga compositions was systematically studied with special emphasis to quantifying the magnetoelastic auxetic‐like response to an applied magnetic field and comparing results with previously published data of the auxetic response of Galfenol to applied stress.…”

Section: Introductionmentioning

confidence: 99%

“…Comparison of negative strain ratio values obtained from the negative ratio of transverse and longitudinal strain data produced by a uniaxial force, where the force was introduced by: a tension test with no magnetic field (green) (Kellogg ); a tension test in the presence of a low (below saturation) DC magnetic field (red) (Yoo and Flatau ); and magnetic saturation and no mechanical load (blue) (Raghunath and Flatau ) (graph from Ref. ).…”

Section: Introductionmentioning

confidence: 99%

“…In Ref. , it was conjectured that this trend could be attributed to restriction of lattice softening due to an increase in the magnetic anisotropy energy that causes a larger interaction between electron spins of neighboring atoms that constitute the crystal lattice. Here, we investigate this idea further and advance the understanding of the atomic‐scale magneto‐elastic coupling that leads to the observed magnetoelastic auxetic‐like behavior by presenting simulations developed based on density functional theory.…”

Section: Introductionmentioning

confidence: 99%

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Magnetoelastic auxetic‐like behavior in Galfenol: Experimental data and simulations

Raghunath

Flatau

Wang³

et al. 2016

Physica Status Solidi (b)

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Iron-gallium alloy (galfenol) is a body centered cubic (BCC) magnetostrictive alloy that, like many other BCC metals, is auxetic in the h110i{100} directions. For compositions of 12-33 at.% gallium, Poisson ratio (n) values as low as À0.7 are observed along these directions in response to a uniaxial elastic force (tensile tests, resonant ultrasound spectroscopy, etc.). In 2014, Raghunath and Flatau first reported that galfenol also exhibits positive strain in both these directions when the uniaxial force applied along the h110i{100} directions is provided solely by a magnetic field, i.e., with no external mechanical/elastic force or stress being applied to the alloy [Raghunath and Flatau, IEEE Trans. Magn. 50(11), 1-4 (2014)]. The observed response is a result of the intrinsic, atomic-scale, bi-directionally coupled magnetoelastic properties of these alloys. In this paper, we advance the understanding of the intrinsic atomic-scale magnetoelastic coupling of the alloy that leads to the observed magnetoelastic auxetic-like behavior by presenting simulations developed based on density functional theory, which we show match the experimental findings and energy-based simulations. The elastic anisotropy and the electronic mechanisms that lead to magnetoelastic auxetic-like behavior in galfenol are discussed.

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Section: Introductionsupporting

confidence: 67%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnetoelastic auxetic‐like behavior in Galfenol: Experimental data and simulations

Raghunath

Flatau

Wang³

et al. 2016

Physica Status Solidi (b)

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Study of magnetic domain evolution in an auxetic plane of Galfenol using Kerr microscopy

Raghunath

Flatau

2015

Journal of Applied Physics

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Galfenol (Fe x Ga100À x ), a magnetostrictive alloy (3/2k 110-400 ppm) of Iron and Gallium exhibits an in-plane auxetic response in the h110i crystallographic direction. Negative Poisson's ratios have been observed in response to application of stress fields, where values of as low as À0.7 have been reported for compositions of greater than roughly 20% Ga [Zhang et al., J. Appl. Phys. 108(2), 023513 (2010)] and in response to application of magnetic fields, where values of as low as À2.5 have been reported to be expected for compositions of less than roughly 20% Ga [G. Raghunath and A. B. Flatau, IEEE Trans. Magn. (in press)]. Several models have been proposed to understand these two distinct phenomena. Galfenol samples with less than 20% Ga also exhibit an unusual response to an increasing magnetic field applied along the h110i direction. The longitudinal strain which increases initially with applied field experiences a dip (until $10 mT) before increasing again to reach saturation. The transverse strain increases and reaches a maximum value (at the same field of $10 mT) and then drops from the maximum by 5%-10% as magnetic saturation is approached [G. Raghunath and A. B. Flatau, IEEE Trans. Magn. (in press)].This work deals with discussing the evolution of magnetic domains in a 16 at. % Ga single crystal Galfenol sample when subjected to magnetic fields in the h110i direction in the (100) plane. The magnetic domains on the surface of mechanically polished Galfenol samples were imaged using Magneto-Optic Kerr Effect microscopy. Simultaneously, the strains along the longitudinal and transverse h110i directions were recorded using a bi-directional strain gauge rosette mounted on the unpolished bottom surface of the planar samples. The energy from the applied magnetic field is expected to grow the h110i oriented domains at the expense of domains oriented along all other directions. But since the plane has an easy h100i axis, we expect the domains to orient along the easy direction before saturating along the applied magnetic field direction. A correlation between the images recorded and the strains observed will be used to understand this shift of domains and bump in strain at low fields. V C 2015 AIP Publishing LLC. [http://dx.

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Design, processing and characterization of mechanically alloyed galfenol & lightly rare-earth doped FeGa alloys as smart materials for actuators and transducers

Taheri¹

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Smart materials find a wide range of application areas due to their varied response to external stimuli [1][2][3]. The different areas of application can be in our day to day life, aerospace, civil engineering applications [4], and mechatronics [5] to name a few.Magnetostrictive materials are a class of smart materials that can convert energy between the magnetic and elastic states [2,6]. Galfenol is a magnetostrictive alloy comprised primarily of the elements iron (Fe) and gallium (Ga) [7]. Galfenol exhibits a unique combination of mechanical and magnetostrictive (magnetic) properties that legacy smart materials do not [8,9]. Galfenol's ability to function while in tension, mechanical robustness and high Curie temperature (600 °C) is attracting interest for the alloy's use in I want to thank to Dr. Yajie Chen, for his unconditional helps and great scientific ideas during my PhD studies.I would also want to thank all my lab mate in CM3IC for their great collaborations, supports and helps. I greatly appreciate the contributions of Dr. Radhika Barua for scientific part of this dissertation. I also want to thank my committee member, Prof.Yongmin Liu. Many thanks goes to our collaborators in Baotou Research Institute of Rare earth in China (L. Jiang's group) and M. R. Koblischka's group in Saarland University in Germany.Last but not least, I would like to specially thank and express my gratitude to my husband Dr. Ramis Movassagh for his understanding and love during the past few years.His professional and moral support, encouragement and unlimited patience was in the end what made this dissertation possible. My parents, Sharif and Parvin and my dear brother, Saeid receive my deepest gratitude and love for their dedication and the many years of support despite being far from me. This dissertation is dedicated to them. 6 TABLE OF CONTENTSdesign, Processing and Characterization of lightly rare-earth doped Fega alloys as smart materials

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Investigation of the Interaction of Magnetic Field With the Auxetic Behavior of Galfenol

Cited by 4 publications

References 22 publications

Magnetoelastic auxetic‐like behavior in Galfenol: Experimental data and simulations

Magnetoelastic auxetic‐like behavior in Galfenol: Experimental data and simulations

Study of magnetic domain evolution in an auxetic plane of Galfenol using Kerr microscopy

Design, processing and characterization of mechanically alloyed galfenol & lightly rare-earth doped FeGa alloys as smart materials for actuators and transducers

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