Magnetic microstructure on surface and in bulk of NANOPERM-type nanocrystalline alloys: Mössbauer effect studies

Miglierini, Marcel; Seberíni, M.; Tóth, I.; Vitázek, K.

doi:10.1016/s0304-8853(03)00272-5

Cited by 8 publications

(4 citation statements)

References 16 publications

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“…The error range in the determination of the relative fraction is comparable with the size of the symbols used. The results, presented in this figure, are in good agreement with the previous observations of the crystallization processes in the amorphous and nanocrystalline alloys [26][27][28][29] that the crystallization process starts on the surface at lower annealing temperature in comparison with the bulk. The temperature of the onset of (surface) crystallization was determined to be 410 • C.…”

Section: Cems and Tms Analysissupporting

confidence: 92%

“…Moreover, the system seems to be an appropriate candidate especially for case studies of hyperfine interactions using Mössbauer effect techniques [25]. An underlying goal of this research took into consideration the results of the previous reports which suggested that the formation of crystallites occurs more easily at the surface than in the bulk [26][27][28][29]. Differences in bulk and surface crystallization have already been pointed out in metal-metalloid glasses [30].…”

Section: Introductionmentioning

confidence: 97%

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AFM and Mössbauer spectrometry investigation of the nanocrystallization process in Fe–Mo–Cu–B rapidly quenched alloy

Pavúk

Miglierini

Vůjtek³

et al. 2007

J. Phys.: Condens. Matter

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In this paper, the effect of heat treatment on the development of nanocrystallites in rapidly quenched Fe79Mo8Cu1B12 alloy is investigated. The surface morphology is examined using non-contact mode atomic force microscopy (AFM). The results are compared with those obtained by transmission Mössbauer spectroscopy (TMS), conversion electron Mössbauer spectrometry (CEMS) and x-ray diffraction (XRD). It was found that the sample is not fully amorphous even in the as-quenched state. Minor amounts of bcc-Fe grains were detected on the wheel side of the ribbon-shaped samples while no indications of the crystalline phase were observed in the bulk. The crystallization onset is observed after annealing at 410 °C, when bcc-Fe nanograins are quite well developed. More intense crystallization is evidenced after annealing at higher temperatures, when the content of the crystalline phase increases progressively. The second crystallization, not discussed in the present paper, is characterized by the occurrence of additional crystalline phases, and appears after annealing at 650 °C. We suggest a crystallization model assuming no drastic change in the size of the primarily formed bcc-Fe nanograins with temperature as proved by XRD. The increase in annealing temperature induces the formation of a higher number of crystalline particles, which form large irregular agglomerates (80–130 nm in height), in accordance with the AFM data.

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Section: Cems and Tms Analysissupporting

confidence: 92%

Section: Introductionmentioning

confidence: 97%

AFM and Mössbauer spectrometry investigation of the nanocrystallization process in Fe–Mo–Cu–B rapidly quenched alloy

Pavúk

Miglierini

Vůjtek³

et al. 2007

J. Phys.: Condens. Matter

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“…As for the sources of the stress, the so-called macroscopic heterogeneity (MH) [1] is considered in this work. MH is the term [2] we propose to encompass certain effects connected to: "native oxide layer" [3], "different SRO at the surfaces" [4] and "surface crystallization" [5]. The quoted terms have something common -all point to a largescale heterogeneity across the ribbon thickness, ie to various differences between the surfaces (surface-adjacent layers) and the deeper layers (interior).…”

Section: Introductionmentioning

confidence: 99%

Application Potential of Nanocrystalline Ribbons Still Pending

Butvin¹,

Butvinová²,

Švec³

et al. 2010

Journal of Electrical Engineering

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Nanocrystalline soft-magnetic ribbons promised a wide-spread practical use when introduced at the beginning of nineties. After 20 years of extensive research there are still unclear material problems which are thought to be the principal reason why these materials show but marginal use. Poorly controllable magnetic anisotropy due to spontaneous intrinsic macroscopic stress that comes from an inevitable heterogeneity of the ribbon materials is pointed to in this work. Certain stress-based mechanisms are shown to induce the unintended anisotropy in the already familiar Finemets as well as in the newer Hitperms. Hysteresis loops, domain structure and power loss is used to reveal the anisotropy consequences and particular connected but still unanswered questions are pinpointed.

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“…However, it results in very low Curie temperatures (T C ∼ room temperature) both in the quenched state and in relaxed and partly crystallized states of the alloy, which promises interesting applications in the future. The magnetic properties of the system were reported in [8][9][10][11], influence of the Fe/B ratio on the thermodynamic properties was studied in [12] and the kinetic characterization of nanocrystal formation in Fe 76 Mo 8 Cu 1 B 15 was done in [13]. It was found [13] that the devitrification of FeMoCuB is a multistage process that does not follow the simple Johnson-Mehl-Avrami kinetics.…”

Section: Introductionmentioning

confidence: 99%

Diffusion and structural changes in Fe_91−yMo₈Cu₁B_yalloys

Čermák

Stloukal

2007

J. Phys.: Condens. Matter

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Fe and Mo tracer diffusion in Fe91−yMo8Cu1By alloys was studied by the serial sectioning method in the temperature interval 548–773 K. The measurement was done with three alloys differing in Fe/B ratio (y = 12, 15 and 17) prepared by the planar flow casting technique, in relaxed and crystallized states. Three modes of Fe diffusion were observed: (i) the slowest one is volume diffusion in the relaxed amorphous (RA) phase, (ii) faster diffusion occurs along the interfaces between crystallites (C) and the RA phase, and (iii) the fastest diffusion was observed along grain boundaries (C/C). It was found that the rate of Mo volume diffusion in the relaxed amorphous phase is approximately the same as that of Fe, but Mo diffusion is much slower than Fe diffusion in grain boundaries. The activation enthalpy of Mo grain boundary diffusion increases with increasing concentration of B. The characteristics of short-circuit diffusion in structures where the relative fraction of RA/C-type interfaces prevail over the C/C-type ones depend sensitively on the thermal treatment.

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Magnetic microstructure on surface and in bulk of NANOPERM-type nanocrystalline alloys: Mössbauer effect studies

Cited by 8 publications

References 16 publications

AFM and Mössbauer spectrometry investigation of the nanocrystallization process in Fe–Mo–Cu–B rapidly quenched alloy

AFM and Mössbauer spectrometry investigation of the nanocrystallization process in Fe–Mo–Cu–B rapidly quenched alloy

Application Potential of Nanocrystalline Ribbons Still Pending

Diffusion and structural changes in Fe_91−yMo₈Cu₁B_yalloys

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Magnetic microstructure on surface and in bulk of NANOPERM-type nanocrystalline alloys: Mössbauer effect studies

Cited by 8 publications

References 16 publications

AFM and Mössbauer spectrometry investigation of the nanocrystallization process in Fe–Mo–Cu–B rapidly quenched alloy

AFM and Mössbauer spectrometry investigation of the nanocrystallization process in Fe–Mo–Cu–B rapidly quenched alloy

Application Potential of Nanocrystalline Ribbons Still Pending

Diffusion and structural changes in Fe91−yMo8Cu1Byalloys

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Product

Resources

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Diffusion and structural changes in Fe_91−yMo₈Cu₁B_yalloys