Nano-magnetism of magnetostriction in Fe35Co65

Lisfi, A.; Ren, Tianhao; Khachaturyan, A. G.; Wuttig, Manfred

doi:10.1063/1.4866183

Cited by 25 publications

(5 citation statements)

References 20 publications

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“…In the commonly investigated “quenched” and “slow‐cooled” FeGa samples the transformation is less apparent although the maximum reported here, Figure , has been observed before albeit much less pronounced . It has even been observed in the magnetostriction characteristic of Co 65 Fe 35 . In general, we observe that iron‐based solid solutions Fe−Si, −Ge, −Al, −Ga, −Co and –Pd share many of the macroscopic characteristics, e.g., the softening of C’ and the Permendur character of their magnetization curves are of similar origin.…”

mentioning

confidence: 41%

Transformation‐Induced Magnetoelasticity in FeGa Alloys

et al. 2019

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Global or local phase transformations are commonly used to create or improve useful properties of materials: the functionality of shape memory alloys is enabled by a global thermoelastic transformation. Transformation‐induced plasticity (TRIP) steels and the creation of transformation‐toughened ceramics are examples of materials innovations through local martensitic phase transformations. This research is undertaken to elucidate the nature of the large magnetostriction in FeGa alloys. An investigation of the evolution of the alloy's nanostructure in the varying magnetic fields of the objective lens of an electron microscope reveals the mechanism leading to the large magnetostriction; it is caused by a local martensitic transformation of the DO3 nanoprecipitates to a 6M phase, leading to transformation‐enhanced magnetoelasticity. The analysis of macroscopic elastic, magnetostriction, and magnetic torque data corroborates this finding.

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mentioning

confidence: 41%

Transformation‐Induced Magnetoelasticity in FeGa Alloys

et al. 2019

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“…While some of these values appear to be trending toward higher values than those measured in older publications for the B2 phase region, more recent research has also measured higher values for Fe 50 Co 50 and Fe 35 Co 65 (k 100 ¼ 176 ppm for 50:50). 14,15 To reach the positive value predicted by first principles calculations for pure Fe (k 111 ¼ 12 Â 10 À6 ), approximately 13 at. % added Co would be required.…”

Section: Discussionmentioning

confidence: 92%

Rhombohedral magnetostriction in dilute iron (Co) alloys

Jones

Petculescu

Wun‐Fogle

et al. 2015

Journal of Applied Physics

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Iron is a well-utilized material in structural and magnetic applications. This does not mean, however, that it is well understood, especially in the field of magnetostriction. In particular, the rhombohedral magnetostriction of iron, λ111 , is anomalous in two respects: it is negative in sign, in disagreement with the prediction of first principles theory, and its magnitude decreases with increasing temperature much too rapidly to be explained by a power law dependence on magnetization. These behaviors could arise from the location of the Fermi level, which leaves a small region of the majority 3d t2g states unfilled, possibly favoring small internal displacements that split these states. If this view is correct, adding small amounts of Co to Fe fills some of these states, and the value of λ111 should increase toward a positive value, as predicted for perfect bcc Fe. We have measured the magnetostriction coefficients (λ111 and λ100) of pure Fe, Fe97Co3, and Fe94Co6 single crystals from 77 K to 450 K. Resonant ultrasound spectroscopy has been used to check for anomalies in the associated elastic constants, c 44 and c′. The additional electrons provided by the cobalt atoms indeed produced positive contributions to bothmagnetostriction constants, λ111 and λ100, exhibiting an increase of 2.8 × 10 −6 per at. % Co for λ111 and 3.8 × 10 −6 per at. % Co for λ100. Iron is a well-utilized material in structural and magnetic applications. This does not mean, however, that it is well understood, especially in the field of magnetostriction. In particular, the rhombohedral magnetostriction of iron, k 111 , is anomalous in two respects: it is negative in sign, in disagreement with the prediction of first principles theory, and its magnitude decreases with increasing temperature much too rapidly to be explained by a power law dependence on magnetization. These behaviors could arise from the location of the Fermi level, which leaves a small region of the majority 3d t 2g states unfilled, possibly favoring small internal displacements that split these states. If this view is correct, adding small amounts of Co to Fe fills some of these states, and the value of k 111 should increase toward a positive value, as predicted for perfect bcc Fe. We have measured the magnetostriction coefficients (k 111 and k 100 ) of pure Fe, Fe 97 Co 3 , and Fe 94 Co 6 single crystals from 77 K to 450 K. Resonant ultrasound spectroscopy has been used to check for anomalies in the associated elastic constants, c 44 and c 0 . The additional electrons provided by the cobalt atoms indeed produced positive contributions to both magnetostriction constants, k 111 and k 100 , exhibiting an increase of 2.8 Â 10 À6 per at. % Co for k 111 and 3.8 Â 10 À6 per at. % Co for k 100 . V C 2015 AIP Publishing LLC. [http://dx

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“…The trace‐doping approach to enhancing magnetostriction may be applied to other two‐phase systems, such as Fe‐Co, Fe‐Al, and Fe‐Pd, where nanoheterogeneities provide a local distortion of the matrix. Furthermore, unlike existing giant magnetostrictive materials such as Terfenol‐D (Tb 0.3 Dy 0.7 )Fe 2 that contain a large proportion of expensive heavy rare earth elements, our alloys with comparable magnetostriction are obtained by trace doping with just 0.6 wt% of much cheaper La.…”

Section: Discussionmentioning

confidence: 97%

Interaction of Trace Rare‐Earth Dopants and Nanoheterogeneities Induces Giant Magnetostriction in Fe‐Ga Alloys

Jiang

et al. 2018

Adv Funct Materials

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The discovery of a tenfold increase in magnetostriction of Fe by alloying nonmagnetic Ga was a breakthrough in magnetostrictive materials. The large magnetostriction is attributed to tetragonal nanoheterogeneities dispersed in the bcc matrix. A further remarkable fivefold increase is achieved by trace rare earth doping (<1 at%) up to a value of ≈1500 ppm, more than 50 times that of pure iron. However, it remains a mystery why trace rare earth dopants can induce such giant magnetostriction. Here, it is found that interaction of rare earth dopants with the nanoheterogeneities produces the giant magnetostriction, through a combination of experimental studies, firstprinciples calculation and phase field simulations. The dopants tend to enter the nanoheterogeneities, increasing their distortion thereby creating a larger tetragonal distortion of the matrix as well as increased magnetocrystalline anisotropy. A mesoscopic model is developed using phase field simulation showing that the bulk tetragonal distortion arises mainly from those nanoheterogeneities with fixed Ga-Ga pairs parallel to the applied magnetic field. Increased tetragonal distortion of the doped nanoheterogeneities leads to further distortion of the matrix. The results deepen the understanding of heterogeneous magnetostriction, and will guide the search for new magnetic materials with giant magnetostriction.

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Nano-magnetism of magnetostriction in Fe35Co65

Cited by 25 publications

References 20 publications

Transformation‐Induced Magnetoelasticity in FeGa Alloys

Transformation‐Induced Magnetoelasticity in FeGa Alloys

Rhombohedral magnetostriction in dilute iron (Co) alloys

Interaction of Trace Rare‐Earth Dopants and Nanoheterogeneities Induces Giant Magnetostriction in Fe‐Ga Alloys

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