Detection and quantification of D03 chemical order in Fe–Ga alloys using high resolution X-ray diffraction

Lograsso, Thomas A.; Summers, Eric

doi:10.1016/j.msea.2005.10.035

Cited by 108 publications

(68 citation statements)

References 7 publications

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“…An Fe 80 Ga 20 sample prepared by blade milling of arc-melted alloy was reported to be completely disordered from Mössbauer spectroscopy results 12 while the Fe-Ga alloys were claimed to have some degree of Ga SRO in another Mössbauer investigation of the Fe-Ga prepared by rapid solidification. 13 Transmission electron microscopy ͑TEM͒, 10 neutron diffraction, 11,14 and conventional x-ray diffraction 15,16 studies did not report the presence of the SRO in the single crystals of Fe-Ga alloys prepared via water quenching or rapid solidification. In conventional x-ray diffraction studies, SRO is difficult to quantitatively characterize because of the extremely weak peak intensity of the SRO diffuse scattering due to the close x-ray atomic factors between Fe and Ga atoms.…”

Section: Introductionmentioning

confidence: 99%

Relation between Ga ordering and magnetostriction of Fe-Ga alloys studied by x-ray diffuse scattering

Huang

Chang

et al. 2010

Phys. Rev. B

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Transmission synchrotron diffraction was employed to characterize the Ga ordering in magnetostrictive Fe 100−x Ga x alloys with Ga concentrations from 0 to 20.3 at. %. The experiments focused on the development of atomic short-range ordering (SRO) by analysis of the diffuse scattering appearing at superlattice positions of the D0 3 ordered alloy structure. No SRO was found for Ga concentrations less than 4 at. %. Between 13 and 20.3 at. %, D0 3 -type SRO clusters are observed whose size increases with Ga concentration for both slowcooled and quenched samples. Thermal quenching of the samples suppresses the cluster sizes when compared to slow-cooled samples of the same concentration. For quenched samples with large Ga concentration, Ga pairing is evidenced by growing B2-type correlations. At low concentrations, the presence of SRO appears to have little (if any) effect on the enhanced magnetostriction. However, the dramatic suppression of magnetostriction near ∼20 at. % Ga can be linked rapid growth of SRO just before the onset of long-range chemical order. Transmission synchrotron diffraction was employed to characterize the Ga ordering in magnetostrictive Fe 100−x Ga x alloys with Ga concentrations from 0 to 20.3 at. %. The experiments focused on the development of atomic short-range ordering ͑SRO͒ by analysis of the diffuse scattering appearing at superlattice positions of the D0 3 ordered alloy structure. No SRO was found for Ga concentrations less than 4 at. %. Between 13 and 20.3 at. %, D0 3 -type SRO clusters are observed whose size increases with Ga concentration for both slowcooled and quenched samples. Thermal quenching of the samples suppresses the cluster sizes when compared to slow-cooled samples of the same concentration. For quenched samples with large Ga concentration, Ga pairing is evidenced by growing B2-type correlations. At low concentrations, the presence of SRO appears to have little ͑if any͒ effect on the enhanced magnetostriction. However, the dramatic suppression of magnetostriction near ϳ20 at. % Ga can be linked rapid growth of SRO just before the onset of long-range chemical order.

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Section: Introductionmentioning

confidence: 99%

Relation between Ga ordering and magnetostriction of Fe-Ga alloys studied by x-ray diffuse scattering

Huang

Chang

et al. 2010

Phys. Rev. B

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“…Local short-range ordering of the Ga atoms along the ͓100͔ direction in the disordered Fe structure has been suggested to be responsible for this increase 10 but experimental confirmation still remains a challenge. 11,12 This is because the peaks corresponding to both D0 3 and A2 phases overlap except for the weak satellite peaks corresponding to the ordered structure. These satellite peaks can generally not be clearly identified due to the very low relative intensities found using x-ray diffraction.…”

Section: Introductionmentioning

confidence: 99%

Neutron diffraction studies of magnetostrictive Fe–Ga alloy ribbons

Zhao

Mellors

Kilcoyne

et al. 2008

Journal of Applied Physics

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Melt-spun Fe-Ga ribbons were prepared and some ribbons were annealed at 1000°C for 1 h then slowly cooled to room temperature. X-ray diffraction patterns revealed no evidence of texture and only bcc phase in the as-quenched ribbons. However, high-resolution neutron diffraction patterns gave more information on the structure of these ribbons. Only diffractions from the disordered bcc A2 phase were found in as-quenched ribbons with 15, 17.5, and 19.5 at. % Ga content, without any trace of satellite peaks or splitting peaks from the proposed Ga-Ga pairing superlattice structure. The broadening of the base of the ͑110͒ peaks for all samples except the as-quenched 15 at. % Ga ribbon might indicate the existence of some kind of short range ordering. Ribbons developed L1 2 phase after annealing especially in the Fe 19.5 at. % Ga ribbon where the formation of L1 2 phase reduced the Ga content in the remaining A2 phase and decreased its lattice parameter dramatically. D0 3 phase formed in the as-quenched 22.5 at. % Ga ribbon and the following annealing treatment transformed more A2 phase into D0 3 phase.

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“…The alloys exhibit superior magnetostrictive properties at low field, negligible magnetic hysteresis, high mechanical strength, good ductility, and low cost [1][2][3]. Although the exact nature of this magnetostrictive behaviour is still to be understood, recent studies have suggested that there is a close correlation between the structure of these alloys and their resulting magnetostrictive performance [4][5][6]. Therefore in order to understand the origin of the magnetostrictive effect in Fe-Ga alloys, knowledge of both the phase constitutions and the short range ordering within these phases is required.…”

Section: Introductionmentioning

confidence: 99%

“…Rapid cooling of Fe 100-x Ga x crystals (with 18 < x < 21) results in an alloy entirely in the A2 phase [9]. However, the phase formation after slow cooling is open to debate: Lograsso et al established that bulk Fe 100-x Ga x alloys with 18 < x < 21 and cooled at a rate of 2 °C/min exhibited a two-phase mixture of A2 and D0 3 [5], a similar result was noted by Zhang et al in Fe 81 Ga 19 ribbons cooled at 1.29 °C/min [10].…”

Section: Introductionmentioning

confidence: 99%

“…Experimental confirmation of these hypotheses still remains a challenge [5,14] particularly as the phase diagram and the magnetostrictive behaviour of the alloys is strongly dependent upon the form of the alloy (bulk, single crystal, thin film, melt spun ribbon etc). It is difficult to confirm the D0 3 ordering in Fe-Ga alloys using standard diffraction techniques because, with the exception of the satellite peaks corresponding to the ordered superlattice structure, many of the peaks corresponding to both D0 3 and A2 phases overlap.…”

Section: Introductionmentioning

confidence: 99%

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A Mössbauer spectroscopy and neutron diffraction study of magnetostrictive, melt-spun Fe–Ga alloy ribbons

Mellors

Zhao

Simmons

et al. 2012

Journal of Magnetism and Magnetic Materials

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Ribbons of Fe 100−x Ga x (x = 15, 17.5, 19.5 and 22.5) were prepared by rapid solidification from the melt. 57Fe Mössbauer spectroscopy and high resolution neutron diffraction have revealed that Fe 100-x Ga x alloys with x = 15 and 17.5 have the disordered bcc (A2) structure even after annealing, but the alloy with x = 19.5 developed the short-range ordered D0 3 phase when annealed. The x = 22.5 alloys showed mainly D0 3 phase with a fraction of bcc phase. A fraction of the bcc phase transformed into D0 3 phase and the long-range ordering of D0 3 phase was improved after annealing. 57Fe Mössbauer spectra showed no observable L1 2 phase in any samples even though less than 1% volume of L1 2 phases have been found in the annealed samples by neutron diffraction. The additional absorption at hyperfine field of 25 T in x = 22.5 samples was regarded as a result of imperfect D0 3 structure, rather than a L1 2 phase.Keywords: Melt spun FeGa alloys; Magnetostrictive alloys; Mössbauer spectroscopy; neutron diffraction; Short-range order; Ferromagnetism Highlights:Melt-spun Fe 100-x Ga x alloys with (15 ≤ x ≤ 17.5) have a disordered bcc structure.Ribbons with x = 19.5 develop short-range ordered D0 3 phase upon annealing.The x = 22.5 ribbons show mainly D0 3 phase with a fraction of bcc phase.2

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Detection and quantification of D03 chemical order in Fe–Ga alloys using high resolution X-ray diffraction

Cited by 108 publications

References 7 publications

Relation between Ga ordering and magnetostriction of Fe-Ga alloys studied by x-ray diffuse scattering

Relation between Ga ordering and magnetostriction of Fe-Ga alloys studied by x-ray diffuse scattering

Neutron diffraction studies of magnetostrictive Fe–Ga alloy ribbons

A Mössbauer spectroscopy and neutron diffraction study of magnetostrictive, melt-spun Fe–Ga alloy ribbons

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