Ferromagnetic Anomalies in the Surface of Single Crystals of the FeNi System

Vasiliev, M. A.; Gorodetskii, S. D.

doi:10.1002/pssa.2211020262

Cited by 4 publications

(6 citation statements)

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“…In particular, magnetic scattering and polarization of electrons from the Ni(100) face near the critical region [58,59], new morphological transition at the Curie temperature [60], reconstruction of stepped Ni surfaces [61], reversible step rearrangement and segregation on Ni surface at T b 0 [62], and emission of secondary particles during ion sputtering of ferromagnetic metals in the phase transition region [194,195] was observed. In our opinion the first surface ferromagnetic anomalies in alloys were reported by Vasiliev and Gorodetsky [63] and Mamaev et al [64] for the clean surface of an Ni 3 Fe single crystal. The first effect was observed [63] in the course of the continuous registration of the temperature dependence of Bragg maximum intensity I hk (T ).…”

Section: Ferromagnetic Anomaliesmentioning

confidence: 51%

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Surface effects of ordering in binary alloys

Vasiliev

1997

J. Phys. D: Appl. Phys.

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Section: Ferromagnetic Anomaliesmentioning

confidence: 51%

“…LEED intensity of the (00) reflex I 00 and the intensity logarithm ln I 00 versus temperature corresponding to (a) Ni(100) and (b) Ni 3 Fe(100)[63].…”

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confidence: 99%

Surface effects of ordering in binary alloys

Vasiliev

1997

J. Phys. D: Appl. Phys.

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“…The compositional changes induced by the segregation at the surface play an important role in determining the properties of alloy surface and grain boundary such as corrosion, oxidation, and embrittlement. Several studies have been carried out on Fe/Al/Ni binary alloys. − For example, high-temperature sputtering and annealing studies on FeAl surfaces have reported the formation of an Al-segregation layer near the surface. − For Fe/Ni alloys, however, no large segregation was observed due to similar size and surface energy. In Fe 3 Ni, only a limited surface segregation of Ni has been reported due to a magnetic phase transition with a significant temperature dependence. , In addition, no significant segregation was observed on a clean Ni 3 Al(111) surface .…”

Section: Resultsmentioning

confidence: 99%

“…61 Another experiment of Fe 3 Ni(110) surface reported that, due to the magnetic phase transition, the Fe concentration on the surface decreased from roughly 76% to 62% in the temperature range 560−650 K and did not change beyond the temperature range. 62 In addition, in the study of FeAl in various surface orientations using Auger electron spectroscopy (AES), Al segregation was observed in alloy multilayers. 65 All these experimental works are in qualitative agreement with our MD simulation results, demonstrating that our force fields for the Fe/Al/Ni alloys are capable to describe such segregation phenomena.…”

Section: Resultsmentioning

confidence: 99%

“…% at the topmost surface layer . Another experiment of Fe 3 Ni(110) surface reported that, due to the magnetic phase transition, the Fe concentration on the surface decreased from roughly 76% to 62% in the temperature range 560–650 K and did not change beyond the temperature range . In addition, in the study of FeAl in various surface orientations using Auger electron spectroscopy (AES), Al segregation was observed in alloy multilayers .…”

Section: Resultsmentioning

confidence: 99%

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Development and Validation of a ReaxFF Reactive Force Field for Fe/Al/Ni Alloys: Molecular Dynamics Study of Elastic Constants, Diffusion, and Segregation

et al. 2012

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We have developed a ReaxFF force field for Fe/Al/Ni binary alloys based on quantum mechanical (QM) calculations. In addition to the various bulk phases of the binary alloys, the (100), (110) and (111) surface energies and adatom binding energies were included in the training set for the force field parametrization of the Fe/Al/Ni binary alloys. To validate these optimized force fields, we studied (i) elastic constants of the binary alloys at finite temperatures, (ii) diffusivity of alloy components in Al/Ni alloy, and (iii) segregation on the binary alloy surfaces. First, we calculated linear elastic constants of FeAl, FeNi(3), and Ni(3)Al in the temperature range 300 to 1100 K. The temperature dependences of the elastic constants of these three alloys, showing a decrease in C(11), C(12), and C(44) as temperature increases, were in good agreement with the experimental results. We also performed ReaxFF molecular dynamics (MD) simulations for Al or Ni diffusion in the system modeled as Al/Ni mixed layers with the linear composition gradients. At 1000 K, Al diffusivity at the pure Al end was 2 orders of magnitude larger than that in the Al trace layers, probably explaining the nature of different diffusion behavior between molten metals and alloys. However, the diffusivity of Ni at the pure Ni end was only slightly larger than that in the Ni trace layers at the system temperature much lower than the melting temperature of Ni. Third, we investigated the surface segregation in L1(2)-Fe(3)Al, Fe(3)Ni, and Ni(3)Al clusters at high temperature (2500 K). From the analysis of composition distribution of the alloy components from the bulk to the surface layer, it was found that the degree of segregation depended on the chemical composition of the alloy. Al surface segregation occurred most strongly in Fe(3)Al, whereas it occurred most weakly in Ni(3)Al. These results may support the segregation mechanism that surface segregation results from the interplay between the energetic stability of the ordered bulk phase and the surface reconstruction. In addition, the surface segregation induced the depletion layers of segregating metal species (Al in Fe(3)Al and Ni(3)Al, and Ni in Fe(3)Ni) next to the segregation layers. These simulation results qualitatively agreed with early experimental observations of segregation in Fe/Al/Ni binary alloys.

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