Magnetic after-effects of hydrogen in amorphous Co75Si15B10 alloys

Moser, N.; Kronmüller, H.

doi:10.1016/0375-9601(82)90227-4

Cited by 6 publications

(3 citation statements)

References 10 publications

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“…N. Moser et al [19] envisagent un effet inverse pour expliquer leurs résultats de traînage magnétique sur un verre Co7sSi1sB1o brut d'élaboration : ils attribuent l'augmentation du pic de réluctivité après recuit entre 260 K et 350 K à la dissociation d'amas d'hydrogène existant initialement après chargement, peut être sous forme d'hydrures. Pour des recuits à des températures supérieures à 330 K, ils observent ensuite une disparition du pic qu'ils attribuent à une désorption de l'hydrogène.…”

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“…Pour des recuits à des températures supérieures à 330 K, ils observent ensuite une disparition du pic qu'ils attribuent à une désorption de l'hydrogène. Les hypothèses avancées par N. Moser et al [19] ne permettent pas d'expliquer nos résultats. En effet, une dissociation d'amas d'hydrogène entraînerait une augmentation du nombre des atomes d'hydrogène participant à la relaxation à 200 K et donc une augmentation du pic de frottement intérieur; c'est l'inverse qui est observé.…”

Section: Discussionunclassified

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Comportement micromécanique d'un verre métallique Fe-B-Si-C chargé en hydrogène

Allemand

Fouquet

Pérez

1986

Rev. Phys. Appl. (Paris)

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2014 Les verres métalliques ferromagnétiques et magnétostrictifs soumis à une contrainte cyclique sont le siège d'un effet magnétoélastique, ou effet 0394E. En frottement intérieur, cet effet se caractérise par un amortissement d'ordre magnétomécanique. Ce comportement micromécanique a été suivi dans le cas d'un verre métallique base fer (Fe83B14Si1,5C1,5) en relation avec l'état structural du matériau. Par ailleurs, le chargement en hydrogène par voie électrolytique sur un tel matériau entraîne la mise en évidence d'un pic de frottement intérieur dont l'origine physique ne peut être uniquement liée au seul phénomène relaxationnel connu sous le nom de pic de Snoek. Il ressort de cette étude l'existence d'une interaction importante entre les parois de domaines ferromagnétiques et les atomes d'hydrogène ainsi que d'une redistribution ou réorientation des atomes d'hydrogène sous l'effet d'un champ magnétique, liée à la nature magnétostrictive du matériau. Abstract. 2014 When a cyclic stress is applied, ferromagnetic and magnetostrictive metallic glasses exhibit a magnetoelastic effect or 0394E-effect. Such an effect is associated to a magnetomechanical damping. This micromechanical behaviour has been studied in the case of an iron-based amorphous alloy (Fe83B14Si1.5C1.5), as a function of the structural state of the material. On the other hand, after electrolytically introducing hydrogen, an internal friction peak is observed. The physical processus leading to such a peak cannot only be attributed to the relaxational phenomenon well known as Snoek peak. A strong interaction between ferromagnetic domain walls and hydrogen atoms and a redistribution or a reorientation of hydrogen atoms under magnetic field, due to the magnetostrictive property of the material, are suggested in order to explain all the expérimental features.

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Comportement micromécanique d'un verre métallique Fe-B-Si-C chargé en hydrogène

Allemand

Fouquet

Pérez

1986

Rev. Phys. Appl. (Paris)

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“…10 The only composition of the CoB-based amorphous alloy in which the atom-scale mechanism of the MAE was suggested is the hydrogen-charged Co 75 Si 15 B 10 . 11 At 190 K, a hydrogen-related relaxation process with a mean activation energy of 0.42 eV was observed. The amorphous CoZr alloy shows an MAE peak from the atom-pair reorientations at 325 K. 12 In this report we are dealing with the MRs in simple representative Co-based amorphous alloys-Co 75 B 25 and Co 75 Si 15 B 10 , in the as-quenched state as well as after the low-temperature annealing.…”

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Evidence of B- and Si-type magnetic relaxations in Co-based amorphous alloys

2004

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The kinetics of the structural magnetic relaxations (MRs) in the Co-based amorphous alloys has been investigated by magnetic after-effect spectroscopy. The experimental evidence and characterization of two types of MRs in the amorphous Co 75 B 25 and Co 75 Si 15 B 10 alloys are rendered in this work. The binary CoB alloy shows only the B-type MR with the most probable energy of the activation energy spectrum Q * = 1.35 eV and the preexponential factor 0 =2ϫ 10 −17 s. In the ternary CoSiB amorphous alloy, the additional Si-type MR with Q * = 1.96 eV and 0 =6ϫ 10 −18 s occurs. Low-temperature annealing shifts either of the relaxation parameters of both alloys to higher values. Roles of the free volumes, the dimension, and affinity of the B and Si atoms for Co in the MR are discussed.The structural magnetic relaxation significantly influences the magnetic properties, processibility, and stability of the amorphous alloys. The Co-based amorphous alloys play an important role in technical applications because of their excellent soft magnetic properties. 1,2 They exhibit good processibility by the magnetic annealing, 3 which the atomic mechanism lies in the magnetic relaxion (MR). A powerful tool for investigating the MR is magnetic after-effect (MAE) spectroscopy. 4 There are two theoretical approaches to MAE in the amorphous alloys. The micromagnetic model of the MR 5 is based on the reorientations of the atom-pair axes near free volumes to the directions related to the local magnetizations (Fig. 1). A driving force for the reorientation is a reduction of the interaction energy of a given atom pair with the local magnetizationwhere 1 and 2 denote the initial and final angles between the atom-pair axis and the local magnetization, 0 is the local interaction energy consisting from exchange ͑ ex ͒, spin-orbit ͑ K ͒, and magnetoelastic ͑ ex ͒ parts, 0 = ex + K + el . Each atom pair acts as an individual two-level system. Assuming the first-order reaction, the time-temperature dependence of the reluctivity influenced by the MR can be expressed by the equation 6where r 0 ͑T͒ is reluctivity at t =0, ⌬r ϳ n 0 is the maximum reluctivity change (n 0 -concentration of mobile atom pairs), p͑͒ is the distribution function of relaxation times , 0 is the preexponential factor, Q is the activation energy, k is the Boltzmann's constant, 00 is a constant of the order of 10 −13 s related to Debye frequency, and S is the activation entropy.By the magnetostrictive model, 7 the magnetostriction of alloy contributes to the MAE level and the MAE appears as independent of the actual alloy composition. The possible role played by the compositions of the amorphous and nanocrystalline alloys in the MRs is not definitely clarified. 8,9 It looks to be reasonable to start an investigation of the MR in Co-based amorphous alloys with a binary CoB alloy. 10 The only composition of the CoB-based amorphous alloy in which the atom-scale mechanism of the MAE was suggested is the hydrogen-charged Co 75 Si 15 B 10 . 11 At 190 K, a hydrogen-related relaxatio...

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Diffusion of hydrogen isotopes in amorphous ferromagnets I. Short-range processes studied by magnetic aftereffect

Hofmann

Kronmüller

1987

Phys. Stat. Sol. (a)

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Dedicated to Prof. Dr. A. SEEGER on the occasion of his 60th birthday The magnetic after-effect spectra of hydrogen and deuterium charged a,morphous ferr0magnet.s Fe,,B,,, Fe,Ni40P,4B,, and Fe,,Zr, are measured in t'he temperature range between 4.2 K and RT. For low H, D-content in all samples reversible relaxation maxima are observed at 200 K shifting to lower temperatures down to 120 K wit'h increasing the H, D-content. The relaxat,ion peaks are very broad and asymmetric. The high temperature region of the relaxat.ion maxima. can be explained by the thermally activated reorientation of H-metalloid(Zr)-complexes where the Hatoms occupy interstitial type positions characterized by a broad spectrum of activation energies (AQ = 0.1 to 0.3 eV) and nearly discrete preexponential factors to. The medium activation energy dccreases from ca. 0.6 eV below to ca. 0.3 eV whereas to shifts from ca. up t o s by increasing the H-content. Charging by deuterium and st,ructural relaxation treatments shift the average activation energy to = 30 meV higher values. Die Spektren der magnetischen Nachwirkung von Wasserstoff-und Deuterium-geladenen amorphen Ferromagneten Fe,B,,, Fe,,,Ni,oP14B, und Fe,,Zr, werden im Temperaturbereich zwischen 4,2 K und R T gemessen. Fur geringen H-, D-Gehalt werden in allen Proben reversible Relaxationsma.xima bei 300 K beobachtet., die sich zu niedrigeren Tempersturen auf 120 K herab mit wachsendem H-, D-Gehalt verschieben. Die Relaxationsmaxima sind sehr breit und asymmetrisch. Der Hochtempcraturbereich der Relaxationsmaxima lal3t sich durch thermisch aktivierte Reorientierung von H-Metalloid(Zr)-Komplexen erklaren, wobei die H-Atome Zwischengitterlagen besetzen, charakterisiert durch ein breites Spektrum von Aktivierungsenergien ( AQ = 0.1 bis 0,3 eV) und nahezu diskrete Exponentialvorfaktoren to. Die mittlere Aktivierungsenergie nimmt von ca. 0.6 eV auf ca.. 0,3 eV ab, wahrend +o sich von ca.. s mit st.eigendem H-Gehalt verschiebt. Beladung mit Deuterium und Strukturrelaxationsbehandlungen verschieben die mittlere Aktivieritngsenergie zu = 30 meV hoheren Werten. bis auf

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Magnetic after-effects of hydrogen in amorphous Co75Si15B10 alloys

Cited by 6 publications

References 10 publications

Comportement micromécanique d'un verre métallique Fe-B-Si-C chargé en hydrogène

Comportement micromécanique d'un verre métallique Fe-B-Si-C chargé en hydrogène

Evidence of B- and Si-type magnetic relaxations in Co-based amorphous alloys

Diffusion of hydrogen isotopes in amorphous ferromagnets I. Short-range processes studied by magnetic aftereffect

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