Mossbauer measurements in iron based alloys with transition metals

Vincze, I.; Campbell, I. A.

doi:10.1088/0305-4608/3/3/023

Cited by 265 publications

(133 citation statements)

References 43 publications

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“…One Al neighbor in the first coordination shell reduces the HF of a Fe atom by 2.3 T and Al neighbors in the second and farther coordination shells can modify this value up to 3 T in the bcc alloy phase. 28 These figures are very close for different nonmagnetic impurities in bcc-Fe, 29 but at interfaces, all the above HF values can be slightly modified by dipolar fields 30 or atomic volume changes due to defect sites. Nevertheless, if we estimate the amount of Fe atoms without Al or Ag first neighbors from the intensity of the components above 30.7 T, it is 58% and 61% for samples 1A and 1B and 71% and 75% for samples 2A and 2B, i.e., the thickness of the pure bcc-Fe layer is 2.0, 2.1, 3.5, and 3.7 nm for the four samples, respectively.…”

Section: Resultsmentioning

confidence: 57%

Chemical mixing at “Al on Fe” and “Fe on Al” interfaces

Süle

Kaptás

Bujdosó

et al. 2015

Journal of Applied Physics

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Section: Resultsmentioning

confidence: 57%

Chemical mixing at “Al on Fe” and “Fe on Al” interfaces

Süle

Kaptás

Bujdosó

et al. 2015

Journal of Applied Physics

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“…The hyperfine field distributions 1 determined for the 32 h powder both in the as received state and in the early stage of the heat treatments ͑at 695 K and 770 K͒ contain a peak at around 30 T, which is not discussed in the paper, but it is certainly attributable 6 to the presence of a significant Cr impurity. It is also important to recognize that the 30 T peak appears in the hyperfine field distribution at that stage when the resonant area of the distribution attributed to grain boundaries is doubled, though the change of the average grain size is minimal and does not exceed the experimental error.…”

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confidence: 93%

Comment on “Grain-boundary structure and magnetic behavior in nanocrystalline ball-milled iron”

et al. 1999

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͓Phys. Rev. B 56, 8894 ͑1997͔͒ published Mössbauer spectroscopy and magnetization measurements on ball-milled iron. The observed changes were attributed to the increased grain-boundary fraction and this was supported by measurements on heat treated samples. The recovery of the physical properties of bulk iron after the heat treatments was attributed to grain growth and atomic rearrangement at the grain boundaries. The effect of possible impurities ͑e.g., Cr originating from the milling tools͒ was not considered in any respect. We show that the results on the heat treated samples do not exclude the possibility of explaining some features of the Mössbauer hyperfine field distribution by impurities instead of a reduced hyperfine field of the grain-boundary atoms. Heat treatments of small grain size Fe 95 Cr 5 samples were performed under argon and in a vacuum of 10 Ϫ7 Pa. Significant reduction of the Cr content of the alloy phase can be observed at elevated temperatures, which is explained by Cr 2 O 3 formation in the surface region.

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“…Those 57 Fe atoms with Cr atoms in their first-and second-nearest-neighbor ͑1NN and 2NN͒ shells have a reduction in HMF of approximately 27 kG for each Cr neighbor. 30 The integer m, where 0 ഛ m ഛ 14, denotes the number of 1NN and 2NN Cr neighbors about a specific 57 Fe atom. The HMF, H͑m͒, can be calculated reasonably well by adding these HMF perturbations from neighboring Cr atoms, 30,33,34 H͑m,…”

Section: A Mössbauer Spectrometrymentioning

confidence: 99%

Vibrational entropy of spinodal decomposition in FeCr

2005

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Inelastic neutron-scattering spectra were measured on stoichiometric Fe 0.50 Cr 0.50 prepared as a bodycentered-cubic ͑bcc͒ solid solution, and after increasing amounts of chemical unmixing on the bcc lattice induced by annealing the solid solution at 773 K. These spectra were reduced by a conventional procedure to a neutron-weighted vibrational density of states. Mössbauer spectrometry was used to characterize the extent of decomposition after annealing. A neutron-weight correction was performed, using results from the Mössbauer spectra and recent data on inelastic nuclear resonant scattering from 57 Fe-Cr. The vibrational entropy of decomposition was found to be −0.17± 0.01k B / atom, nearly equal to the change in configurational entropy after spinodal decomposition. Effects of vibrational entropy on the thermodynamics of unmixing are analyzed, showing a large effect on the free energy with the formation of Cr-rich zones, and a large effect on the critical temperature for spinodal decomposition for equiatomic Fe 0.50 Cr 0.50 .

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Mossbauer measurements in iron based alloys with transition metals

Cited by 265 publications

References 43 publications

Chemical mixing at “Al on Fe” and “Fe on Al” interfaces

Chemical mixing at “Al on Fe” and “Fe on Al” interfaces

Comment on “Grain-boundary structure and magnetic behavior in nanocrystalline ball-milled iron”

Vibrational entropy of spinodal decomposition in FeCr

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