Metastable and transient states of chemical ordering in Fe-V nanocrystalline alloys

Ziller, T.; Caër, G. Le; Isnard, O.; Cénédèse, Pierre; Fultz, B.

doi:10.1103/physrevb.65.024204

Cited by 28 publications

(23 citation statements)

References 55 publications

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“…22 For B2 Fe 0.50 Co 0.50 , an order parameter L = 0.76 was determined from the ratio of the intensities of the ͑100͒ superlattice peak to the ͑110͒ fundamental peak, following the method of Ziller et al 23 The intensity of perfectly ordered B2 FeCo was calculated using the Philips X'PERT PLUS software. After successfully matching the calculated intensity to the fundamental peaks in the experimental data, the measured ͑100͒ superlattice peaks were found to be weaker than calculated in the ratio I meas 100 / I calc 100 Ӎ 0.5.…”

Section: Alloysmentioning

confidence: 99%

Effects of chemical composition and B2 order on phonons in bcc Fe–Co alloys

Lucas

Muñoz

Mauger

et al. 2010

Journal of Applied Physics

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The phonon density of states ͑DOS͒ gives insight into interatomic forces and provides the vibrational entropy, making it a key thermodynamic function for understanding alloy phase transformations. Nuclear resonant inelastic x-ray scattering and inelastic neutron scattering were used to measure the chemical dependence of the DOS of bcc Fe-Co alloys. For the equiatomic alloy, the A2 → B2 ͑chemically disordered→ chemically ordered͒ phase transformation caused measurable changes in the phonon spectrum. The measured change in vibrational entropy upon ordering was −0.02Ϯ 0.02 k B /atom, suggesting that vibrational entropy results in a reduction in the orderdisorder transition temperature by 60Ϯ 60 K. The Connolly-Williams cluster inversion method was used to obtain interaction DOS ͑IDOS͒ curves that show how point and pair variables altered the phonon DOS of disordered bcc Fe-Co alloys. These IDOS curves accurately captured the change in the phonon DOS and vibrational entropy of the B2 ordering transition.

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Section: Alloysmentioning

confidence: 99%

Effects of chemical composition and B2 order on phonons in bcc Fe–Co alloys

Lucas

Muñoz

Mauger

et al. 2010

Journal of Applied Physics

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“…3). An order parameter L ¼ 0:37 was determined from the ratio of the intensities of the (100) and (110) intensities to the (220) fundamental peak, following the method of Ziller et al 16 The intensity of the superlattice peaks for a perfectly ordered sample was calculated by setting L ¼ 1 and solving for the ratio of the intensities (solid diamonds in Fig. 3).…”

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confidence: 99%

Phonon densities of states of face-centered-cubic Ni-Fe alloys

Lucas

Mauger

Muñoz

et al. 2013

Journal of Applied Physics

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Inelastic neutron scattering and nuclear resonant inelastic x-ray scattering were used to determine the phonon densities of states of face-centered-cubic Ni-Fe alloys. Increasing Fe concentration results in an average softening of the phonon modes. Chemical ordering of the Ni0.72Fe0.28 alloy results in a reduction of the partial vibrational entropy of the Fe atoms but does not significantly change the partial vibrational entropy of the Ni atoms. Changes in the phonon densities of states with composition and chemical ordering are discussed and analyzed with a cluster expansion method.

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“…In the case of a transformation without composition change, we would expect to observe a spectrum similar to the one shown by Fig. 6 of [21] for an as-milled bcc Fe 53 V 47 alloy for which the mean field of the sole magnetic part is 14.3 T at RT [21]. Its HMFD consists essentially of a narrow peak at $1 T, which accounts actually for the intense central peak of the spectrum, and of a broad Gaussian-like peak centered on a field of 14.3 T. The bcc phase which forms here is clearly heterogeneous.…”

Section: Resultsmentioning

confidence: 67%

“…A similar brittle phase, also formed in Fe-Cr alloys, is for instance detrimental to their mechanical behavior. A metastable ordered compound FeV with a structure of the B2 type (CsCl) is rather easily formed [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

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Mössbauer spectroscopy and X-ray diffraction studies of ball-milling-induced transformations of a near-equiatomic FeV sigma phase: Influence of oxygen

Costa

Caër

Malaman

et al. 2007

Nuclear Instruments and Methods in Physics Research Section A:

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Abstract57 Fe Mo¨ssbauer spectroscopy and X-ray diffraction were used to study the structural changes induced by ball milling a coarse-grained Fe 48.1 V 51.9 at% sigma phase in a vibratory mill in argon with a frequent gas renewal. The sigma phase transforms into a bcc alpha phase till 140 h of milling. Mo¨ssbauer spectroscopy also shows the presence of an amorphous phase. Further, X-ray diffraction and Mo¨ssbauer spectroscopy reveals the presence of a corundum type oxide (V 1-x Fe x ) 2 O 3 and of a spinel FeV 2 O 4 in samples milled for 140 h and longer. Mo¨ssbauer spectroscopy clearly shows that the spinel phase starts to form after 140 h of milling. Oxidation is progressive and occurs first via an unmixing process which deprives the Fe-V bcc matrix of vanadium atoms. r

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Metastable and transient states of chemical ordering in Fe-V nanocrystalline alloys

Cited by 28 publications

References 55 publications

Effects of chemical composition and B2 order on phonons in bcc Fe–Co alloys

Effects of chemical composition and B2 order on phonons in bcc Fe–Co alloys

Phonon densities of states of face-centered-cubic Ni-Fe alloys

Mössbauer spectroscopy and X-ray diffraction studies of ball-milling-induced transformations of a near-equiatomic FeV sigma phase: Influence of oxygen

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