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Full-Text Articles in Physics

Texture And Grain Morphology Dependencies Of Saturation Magnetostriction In Rolled Polycrystalline Fe83ga17, R. A. Kellogg, A. B. Flatau, A. E. Clark, M. Wun-Fogle, Thomas A. Lograsso May 2013

Texture And Grain Morphology Dependencies Of Saturation Magnetostriction In Rolled Polycrystalline Fe83ga17, R. A. Kellogg, A. B. Flatau, A. E. Clark, M. Wun-Fogle, Thomas A. Lograsso

Ames Laboratory Conference Papers, Posters, and Presentations

Textured polycrystalline Fe-Ga alloys exhibit magnetostrictive strains of 100 ppm or greater and may function as a mechanically robust actuator/sensing material. Current efforts seek to combine the 300+ ppm magnetostrictive strain performance of [100] oriented single crystals with the mechanical properties of polycrystalline forms. One approach to combining these properties is to control the crystallographic texture through deformation processing such as rolling. To determine the relationship between saturation magnetostriction, degree of texturing, and grain morphology we compare the results of three-dimensional finite element simulations with the analytical solution for a random polycrystal and the experimental responses of rolled polycrystalline ...


Tetragonal Magnetostriction And Magnetoelastic Coupling In Fe-Al, Fe-Ga, Fe-Ge, Fe-Si, Fe-Ga-Al, And Fe-Ga-Ge Alloys, J. B. Restorff, M. Wun-Fogle, K. B. Hathaway, A. E. Clark, Thomas A. Lograsso, G. Petculescu Jan 2012

Tetragonal Magnetostriction And Magnetoelastic Coupling In Fe-Al, Fe-Ga, Fe-Ge, Fe-Si, Fe-Ga-Al, And Fe-Ga-Ge Alloys, J. B. Restorff, M. Wun-Fogle, K. B. Hathaway, A. E. Clark, Thomas A. Lograsso, G. Petculescu

Ames Laboratory Publications

This paper presents a comparative study on the tetragonal magnetostriction constant,λγ,2, [ = (3/2)λ100] and magnetoelastic coupling, b1, of binary Fe100-xZx (0 < x < 35, Z = Al, Ga, Ge, and Si) and ternary Fe-Ga-Al and Fe-Ga-Ge alloys. The quantities are corrected for magnetostrains due to sample geometry (the magnetostrictive form effect). Recently published elastic constant data along with magnetization measurements at both room temperature and 77 K make these corrections possible. The form effect correction lowers the magnetostriction by ∼10 ppm for high-modulus alloys and by as much as 30 ppm for low-modulus ...


Magnetostriction, Elasticity, And D03 Phase Stability In Fe–Ga And Fe–Ga–Ge Alloys, G. Petculescu, K. L. Ledet, Mianliang Huang, Thomas A. Lograsso, Y. N. Zhang, R. Q. Wu, M. Wun-Fogle, J. B. Restorff, A. E. Clark, K. B. Hathaway Mar 2011

Magnetostriction, Elasticity, And D03 Phase Stability In Fe–Ga And Fe–Ga–Ge Alloys, G. Petculescu, K. L. Ledet, Mianliang Huang, Thomas A. Lograsso, Y. N. Zhang, R. Q. Wu, M. Wun-Fogle, J. B. Restorff, A. E. Clark, K. B. Hathaway

Ames Laboratory Conference Papers, Posters, and Presentations

The contrast between the saturation tetragonal magnetostriction, λγ,2 = (3/2)λ100, of Fe1−xGax and Fe1−yGey, at compositions where both alloys exhibit D03 cubic symmetry (second peak region), was investigated. This region corresponds to x = 28 at. % Ga and y = 18 at. % Ge or, in terms of e/a = 2 x + 3 y + 1, to an e/a value of ∼1.55 for each of the alloys. Single crystal, slow-cooled, ternary Fe1−xy GaxGey alloys with e/a ∼1.55 and gradually increasing y ...


The Effect Of Partial Substitution Of Ge For Ga On The Elastic And Magnetoelastic Properties Of Fe–Ga Alloys, G. Petculescu, A. O. Mandru, William M. Yuhasz, Thomas A. Lograsso, M. Wun-Fogle, J. B. Restorff, A. E. Clark, K. B. Hathaway Apr 2010

The Effect Of Partial Substitution Of Ge For Ga On The Elastic And Magnetoelastic Properties Of Fe–Ga Alloys, G. Petculescu, A. O. Mandru, William M. Yuhasz, Thomas A. Lograsso, M. Wun-Fogle, J. B. Restorff, A. E. Clark, K. B. Hathaway

Ames Laboratory Conference Papers, Posters, and Presentations

Both components of the tetragonal magnetoelastic constant b1: the saturation magnetostriction, λγ,2 = (3/2)λ100, and the magnetic-field saturated shear elasticity, c′ = (c11c12)/2, were investigated over a wide temperature range for the magnetostrictiveFe1−xyGaxGey alloys, (x+y ≅ 0.125, 0.185, and 0.245; x/y ≅ 1 and 3). The magnetostriction was measured from 77 to 425 K using standard strain gage techniques. Both shear elastic constants (c′ and c44) were measured from 5 to 300 K using resonant ultrasound spectroscopy. Six alloy compositions were ...


Effect Of Carbon Addition On The Single Crystalline Magnetostriction Of Fe-X (X = Al And Ga) Alloys, Mianliang Huang, Yingzhou Du, Robert J. Mcqueeney, Thomas A. Lograsso Mar 2010

Effect Of Carbon Addition On The Single Crystalline Magnetostriction Of Fe-X (X = Al And Ga) Alloys, Mianliang Huang, Yingzhou Du, Robert J. Mcqueeney, Thomas A. Lograsso

Ames Laboratory Publications

The effect of carbon addition on the magnetostriction of Fe–Ga and Fe–Al alloys was investigated and is summarized in this study. It was found that the addition of carbon generally increased the magnetostriction over binary alloys of Fe–Ga and Fe–Al systems. The formation of carbide in the Fe–Ga–C alloys with a composition near D03 phase region decreased the magnetostriction drastically. Fe–Al–C and Fe–Ga–C alloys responded differently to thermal treatments; the magnetostriction in the quenched Fe–Al–C alloys is equal to or slightly lower than that of the slow ...


Magnetoelastic Coupling In Fe100−Xgex Single Crystals With 4, G. Petculescu, J. B. Leblanc, M. Wun-Fogle, J. B. Restorff, William M. Yuhasz, Thomas A. Lograsso, A. E. Clark Mar 2009

Magnetoelastic Coupling In Fe100−Xgex Single Crystals With 4, G. Petculescu, J. B. Leblanc, M. Wun-Fogle, J. B. Restorff, William M. Yuhasz, Thomas A. Lograsso, A. E. Clark

Ames Laboratory Conference Papers, Posters, and Presentations

In this paper we examine the elastic (c′ and c44) and magnetostrictive (λ100 and λ111) behaviors of Fe100−xGex for 4<x<18, quantities used further to find the fundamental magnetoelastic coupling constants b1 and b2 at room temperature. The x dependence ofb1 and b2 for Fe100−xGex is contrasted to those of Fe100−xGax and Fe100−xAlx. While the rhombohedral shear elastic constant c44 is almost insensitive to the type and amount of solute, the tetragonal shear constant c′ shows a pronounced and rapid softening with increasing x for ...


Magnetic Domains In Magnetostrictive Fe–Ga Alloys, Qingfeng Xing, Thomas A. Lograsso Nov 2008

Magnetic Domains In Magnetostrictive Fe–Ga Alloys, Qingfeng Xing, Thomas A. Lograsso

Ames Laboratory Publications

Lorentz microscopy was applied to the observation of magnetic domains in iron-gallium (Fe–Ga) alloys. Results did not show any link between the magnetic domains and the magnetostriction enhancement by Ga addition, but did reveal that the drastic decrease in magnetostriction for Fe–31.2 at. % Ga was due to the presence of large scale precipitates. Magnetic domain features did not change in the alloys of A2, D03, A2+D03,A2+B2+D03, and A2+fine scale precipitates. Large scale precipitates within the slow-cooled Fe–31.2 at. % Ga affected both the distribution and wall motion of ...


Effect Of Interstitial Additions On Magnetostriction In Fe–Ga Alloys, Mianliang Huang, Thomas A. Lograsso, A. E. Clark, J. B. Restorff, M. Wun-Fogle Jan 2008

Effect Of Interstitial Additions On Magnetostriction In Fe–Ga Alloys, Mianliang Huang, Thomas A. Lograsso, A. E. Clark, J. B. Restorff, M. Wun-Fogle

Ames Laboratory Conference Papers, Posters, and Presentations

The additions of trace amounts of small interstitial atoms (carbon, boron, and nitrogen) to Fe–Ga (Galfenol) alloys have a small but beneficial effect on the magnetostriction of Fe–Ga alloys especially at high Ga compositions. The saturated magnetostrictions [(3/2)λ100’s] of both slow cooled and quenched single crystal Fe–Ga–C alloys with Ga contents >18 at. % are about 10%–30% higher than those of the comparable binary Fe–Ga alloys. For boron and nitrogen additions, the magnetostrictions of slow cooled alloys with Ga content >18 at. % were approximately 20% higher than those of the binary ...


Magnetostriction Of Ternary Fe–Ga–X (X = C,V,Cr,Mn,Co,Rh) Alloys, A. E. Clark, J. B. Restorff, M. Wun-Fogle, K. B. Hathaway, Thomas A. Lograsso, Mianliang Huang, E. Summers Apr 2007

Magnetostriction Of Ternary Fe–Ga–X (X = C,V,Cr,Mn,Co,Rh) Alloys, A. E. Clark, J. B. Restorff, M. Wun-Fogle, K. B. Hathaway, Thomas A. Lograsso, Mianliang Huang, E. Summers

Ames Laboratory Conference Papers, Posters, and Presentations

Binary iron-gallium (Galfenol) alloys have large magnetostrictions over a wide temperature range. Single crystal measurements show that additions of 2 at. % or greater of 3d and 4d transition elements with fewer (V, Cr, Mo, Mn) and more (Co, Ni, Rh) valence electrons than Fe, all reduce the saturation magnetostriction. Kawamiya and Adachi [J. Magn. Magn. Mater. 31–34, 145 (1983)] reported that the D03 structure is stabilized by 3dtransition elements with electron∕atom ratios both less than iron and greater than iron. IfD03 ordering decreases the magnetostriction, the maximum magnetostriction should ...


Magnetostructural Transitions And Adiabatic Temperature Variation In Polycrystal And Single-Crystal Ni2mnga Alloys, C. P. Sasso, M. Pasquale, L. Giudici, S. Besseghini, E. Villa, L. H. Lewis, Thomas A. Lograsso, Deborah L. Schlagel Apr 2006

Magnetostructural Transitions And Adiabatic Temperature Variation In Polycrystal And Single-Crystal Ni2mnga Alloys, C. P. Sasso, M. Pasquale, L. Giudici, S. Besseghini, E. Villa, L. H. Lewis, Thomas A. Lograsso, Deborah L. Schlagel

Ames Laboratory Conference Papers, Posters, and Presentations

The magnetocaloric response of off-stoichiometric Ni2MnGa polycrystal and single-crystal samples with a Curie temperature coincident with the martensitic transition temperature was investigated. The direct measurement of temperature change (ΔTad) during an adiabatic transformation under a maximum field variation ΔH = 5.6×106 A/m (7 T) was performed. The polycrystalline sample shows a maximum ΔTad ≈ 1.5 K at a temperature close to the structural transition. The value of ΔTad and the 20 K span of the ΔTad peak encourage further studies of the effect of microstructure on ...


Large Magnetically Induced Strains In Ni50mn28.7ga21.3 Driven With Collinear Field And Stress, A. Malla, M. J. Dapino, Thomas A. Lograsso, Deborah L. Schlagel Mar 2006

Large Magnetically Induced Strains In Ni50mn28.7ga21.3 Driven With Collinear Field And Stress, A. Malla, M. J. Dapino, Thomas A. Lograsso, Deborah L. Schlagel

Ames Laboratory Publications

Despite the huge magnetic-field-induced strain (MFIS) of up to 9.5% exhibited by certain Ni–Mn–Ga alloys, their usefulness in applications is severely hindered by the electromagnet device needed for driving the alloys with a magnetic field and orthogonal loading stress. In this paper we present macroscopic measurements obtained from a single crystal of Ni50Mn28.7Ga21.3 which demonstrate a large reversible MFIS of −4100 ppm when the alloy is driven with quasistatic magnetic fields and fixed compressive stresses applied collinearly along the [001] axis. This collinear configuration marks a fundamental difference with prior ...


Fe–Ga/Pb(Mg1/3nb2/3)O3–Pbtio3 Magnetoelectric Laminate Composites, Shuxiang Dong, Junyi Zhai, Naigang Wang, Feiming Bai, Jiefang Li, D. Viehland, Thomas A. Lograsso Nov 2005

Fe–Ga/Pb(Mg1/3nb2/3)O3–Pbtio3 Magnetoelectric Laminate Composites, Shuxiang Dong, Junyi Zhai, Naigang Wang, Feiming Bai, Jiefang Li, D. Viehland, Thomas A. Lograsso

Ames Laboratory Publications

We have found large magnetoelectric (ME) effects in long-type laminate composites of Fe–20%Ga magnetostrictive alloys and piezoelectric Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystals. At lower frequencies, the ME voltage coefficient of a laminate with longitudinally magnetized and longitudinally polarized (i.e., L-L mode) layers was 1.41 V/Oe (or1.01 V/cm Oe). Near the natural resonant frequency ( ∼ 91 kHz) of the laminate, the ME voltage coefficients were found to be dramatically increased to 50.7 V/Oe (36.2 V/cm Oe)for the L-L mode. In ...


Magnetic Force Microscopy Investigation Of Domain Structures In Fe–X At. % Ga Single Crystals (12, Feiming Bai, Jiefang Li, D. Viehland, D. Wu, Thomas A. Lograsso Jul 2005

Magnetic Force Microscopy Investigation Of Domain Structures In Fe–X At. % Ga Single Crystals (12, Feiming Bai, Jiefang Li, D. Viehland, D. Wu, Thomas A. Lograsso

Ames Laboratory Publications

The domain structure of furnace-cooled (FC) and post-annealed (PA) Fe–x at. % Ga (x = 12, 20, and 25) crystals has been investigated by magnetic force microscopy. For both FC and PA Fe–12 at. % Ga, the domains were found to be well-aligned and oriented along the [100] direction. For Fe–20 at. % Ga, although a preferred [100] orientation remained, a difference in morphology was found between FC and PA conditions—in the PA condition, clear dendritic domains were observed. For both FC and PA Fe–25 at. % Ga, a much reduced [100] preferred domain orientation was found, the domain size ...


Magnetic Field Dependence Of Galfenol Elastic Properties, G. Petculescu, K. B. Hathaway, Thomas A. Lograsso, M. Wun-Fogle, A. E. Clark May 2005

Magnetic Field Dependence Of Galfenol Elastic Properties, G. Petculescu, K. B. Hathaway, Thomas A. Lograsso, M. Wun-Fogle, A. E. Clark

Ames Laboratory Conference Papers, Posters, and Presentations

Elastic shear moduli measurements on Fe100−xGax (x = 12–33) single crystals (via resonant ultrasound spectroscopy) with and without a magnetic field and within 4–300 K are reported. The pronounced softening of the tetragonal shear modulus c′ is concluded to be, based on magnetoelastic coupling, the cause of the second peak in the tetragonal magnetostriction constant λ100 near x = 28. Exceedingly high ΔE effects ( ∼ 25%), combined with the extreme softness in c′ (c′<10 GPa), suggest structural changes take place, yet, gradual in nature, as the moduli show a smooth dependence on Ga concentration, temperature, and magnetic field. Shear anisotropy (c44/c′) as high as 14.7 was observed for Fe71.2Ga28.8.


Temperature Dependence Of The Magnetic Anisotropy And Magnetostriction Of Fe100−Xgax (X = 8.6, 16.6, 28.5), A. E. Clark, M. Wun-Fogle, J. B. Restorff, Kevin W. Dennis, Thomas A. Lograsso, R. William Mccallum May 2005

Temperature Dependence Of The Magnetic Anisotropy And Magnetostriction Of Fe100−Xgax (X = 8.6, 16.6, 28.5), A. E. Clark, M. Wun-Fogle, J. B. Restorff, Kevin W. Dennis, Thomas A. Lograsso, R. William Mccallum

Ames Laboratory Conference Papers, Posters, and Presentations

The temperature dependence of the lowest order magnetic anisotropy constant K1 and the lowest order saturation magnetostriction constant, (3/2)λ100, were measured from 4 K to 300 K for Fe91.4Ga8.6,Fe83.4Ga16.6, and Fe71.5Ga28.5 and were compared to the normalized magnetization power law, ml(l+1)/2. Fe91.4Ga8.6 maintains the magnetostriction anomaly of Fe (dλ100/dT>0) and K1 is a reasonable fit to the ml(l+1)/2power law with ...


Magnetostrictive And Magnetoelectric Behavior Of Fe–20 At. % Ga/Pb(Zr,Ti)O3 Laminates, Shuxiang Dong, Junyi Zhai, Feiming Bai, Jiefang Li, D. Viehland, Thomas A. Lograsso Apr 2005

Magnetostrictive And Magnetoelectric Behavior Of Fe–20 At. % Ga/Pb(Zr,Ti)O3 Laminates, Shuxiang Dong, Junyi Zhai, Feiming Bai, Jiefang Li, D. Viehland, Thomas A. Lograsso

Ames Laboratory Publications

The magnetostrictive and magnetoelectric (ME) properties of laminate composites of Fe–20 at. % Ga and Pb(Zr,Ti)O3 (PZT) have been studied for laminates of different geometries. The results show that (i) a long-type magnetostrictive Fe–20 at. % Ga crystal plate oriented along 〈001〉c and magnetized in its longitudinal (or length) direction has higher magnetostriction than a disk-type one; and consequently (ii) a long-type Fe–20 at. % Ga/PZT laminate has a giant ME effect, and is sensitive to low-level magnetic fields.


Extraordinary Magnetoelasticity And Lattice Softening In Bcc Fe-Ga Alloys, A. E. Clark, K. B. Hathaway, M. Wun-Fogle, J. B. Restorff, Thomas A. Lograsso, V. M. Keppens, G. Petculescu, R. A. Taylor May 2003

Extraordinary Magnetoelasticity And Lattice Softening In Bcc Fe-Ga Alloys, A. E. Clark, K. B. Hathaway, M. Wun-Fogle, J. B. Restorff, Thomas A. Lograsso, V. M. Keppens, G. Petculescu, R. A. Taylor

Ames Laboratory Conference Papers, Posters, and Presentations

Extraordinary magnetostrictive behavior has been observed in Fe-Ga alloys with concentrations of Ga between 4% and 27%. λ100 exhibits two peaks as a function of Ga content. At room temperature, λ100 reaches a maximum of 265 ppm near 19% Ga and 235 ppm near 27% Ga. For compositions between 19% and 27%, λ100 drops sharply to a minimum near 24% Ga and exhibits an anomalous temperature dependence, decreasing by as much as a factor of 2 at low temperatures. This unusual magnetostrictive behavior is interpreted on the basis of a single maximum in the magnetoelastic coupling ∣b ...


Magnetism, Elasticity, And Magnetostriction Of Fecoga Alloys, Liyang Dai, James Cullen, Manfred Wuttig, Thomas A. Lograsso, Eckhard Quandt May 2003

Magnetism, Elasticity, And Magnetostriction Of Fecoga Alloys, Liyang Dai, James Cullen, Manfred Wuttig, Thomas A. Lograsso, Eckhard Quandt

Ames Laboratory Publications

It is known that the substitution of Co for Fe gives rise to increases in magnetization and Curie temperature, not only in the bcc metals, but also in intermetallic compounds and alloys as well. With the expectation that this is the case in Co-substituted FeGa, we measured magnetization, Curie temperature, magnetostriction and elastic constants of a series of polycrystalline FeCoGa ternary alloys with up to 17% Ga and up to 10% Co. The magnetostriction at saturation for Fe0.93−xCo.07Gax increases to 90 ppm for x=0.17. For larger percentages of Co, the rise ...


Structural Studies Of Fe0.81ga0.19 By Reciprocal Space Mapping, D. Viehland, Jiefang Li, Thomas A. Lograsso, A. R. Ross, Manfred Wuttig Oct 2002

Structural Studies Of Fe0.81ga0.19 By Reciprocal Space Mapping, D. Viehland, Jiefang Li, Thomas A. Lograsso, A. R. Ross, Manfred Wuttig

Ames Laboratory Publications

Reciprocal lattice mapping has been performed on Fe0.81Ga0.19 crystals by ω–ω/2θ, Ψ–ϕ, and ω–ϕ scans. A strong elongation of the 〈001〉c peak was found along the〈110〉c direction. ω scans revealed short lateral correlation lengths ξ along 〈110〉cand strong diffuse scattering along the 〈001〉c. Multiple domains with monoclinic symmetry (angle ∼190°) were observed by Ψ–ϕ and ω–ϕ scans on the (001)c face, and were also tilted with respect to each other. The results show an average cubic structure with orthorhombic structural modulations, and ...


Temperature And Stress Dependencies Of The Magnetic And Magnetostrictive Properties Of Fe0.81ga0.19, R. A. Kellogg, Alison B. Flatau, A. E. Clark, M. Wun-Fogle, Thomas A. Lograsso May 2002

Temperature And Stress Dependencies Of The Magnetic And Magnetostrictive Properties Of Fe0.81ga0.19, R. A. Kellogg, Alison B. Flatau, A. E. Clark, M. Wun-Fogle, Thomas A. Lograsso

Ames Laboratory Conference Papers, Posters, and Presentations

It was recently reported that the addition of nonmagnetic Ga increased the saturation magnetostriction (λ100) of Fe over tenfold while leaving the rhombohedral magnetostriction (λ111) almost unchanged. To determine the relationship between the magnetostriction and the magnetization we measured the temperature and stress dependence of both the magnetostriction and magnetization from −21 °C to +80 °C under compressive stresses ranging from 14.4 MPa to 87.1 MPa. For this study a single crystal rod of Fe0.81Ga0.19 was quenched from 800 °C into water to insure a nearly random distribution of Ga atoms ...


Magnetostriction Of Ternary Fe–Ga–X Alloys (X=Ni,Mo,Sn,Al), J. B. Restorff, M. Wun-Fogle, A. E. Clark, Thomas A. Lograsso, A. R. Ross, Deborah L. Schlagel May 2002

Magnetostriction Of Ternary Fe–Ga–X Alloys (X=Ni,Mo,Sn,Al), J. B. Restorff, M. Wun-Fogle, A. E. Clark, Thomas A. Lograsso, A. R. Ross, Deborah L. Schlagel

Ames Laboratory Publications

Investigations were made into the effect of small additions of Ni, Mo, Sn, as well as larger additions of Al on the magnetostriction of single crystal Fe100−xGax alloys (x≅13). The Fe–Ga and Fe–Al systems are seemingly unique among the Fe-based alloys in having very large magnetostrictions in spite of Ga and Al being nonmagnetic. In this paper, we show how additions of Ni, Mo, Sn, and Al affect λ100 and λ111 of the binary Fe–Ga alloys. We substituted small amounts of Ni into a binary Fe–Ga alloy in an ...


6% Magnetic-Field-Induced Strain By Twin-Boundary Motion In Ferromagnetic Ni–Mn–Ga, S. J. Murray, M. Marioni, S. M. Allen, R. C. O'Handley, Thomas A. Lograsso Aug 2000

6% Magnetic-Field-Induced Strain By Twin-Boundary Motion In Ferromagnetic Ni–Mn–Ga, S. J. Murray, M. Marioni, S. M. Allen, R. C. O'Handley, Thomas A. Lograsso

Ames Laboratory Publications

Field-induced strains of 6% are reported in ferromagnetic Ni–Mn–Ga martensites at room temperature. The strains are the result of twin boundary motion driven largely by the Zeeman energy difference across the twin boundary. The strain measured parallel to the applied magnetic field is negative in the sample/field geometry used here. The strain saturates in fields of order 400 kA/m and is blocked by a compressive stress of order 2 MPa applied orthogonal to the magnetic field. The strain versus field curves exhibit appreciable hysteresis associated with the motion of the twin boundaries. A simple model accounts ...