Segregation phenomena on surfaces of the ordered bimetallic alloy FeAl

Hammer, Lutz; Graupner, H.; Blüm, Volker; Heinz, K.; Ownby, G. W.; Zehner, D. M.

doi:10.1016/s0039-6028(98)00370-7

Cited by 40 publications

(68 citation statements)

References 30 publications

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“…Whatever the orientation, the near surface composition obtained is close to the B 2 Fe 0.5 Al 0.5 with a typical affected depth of around 25Å, except on the (110) surface for which those figures are slightly different (Fe 0.6 Al 0.4 ; ∼ 35Å) [17]. Although suspected in the diffraction study of Kottcke et al [19] on FeAl(100) and in the Auger measurements of Hammer et al [20] on the open FeAl(111) surface, such a composition gradient in the Fe 1−x Al x system was never evidenced before, probably because experiments [21,22,23,19,24,20,25,14,26,23,27] have focused mostly on ordered FeAl alloys with higher Al contents.…”

Section: Introductionsupporting

confidence: 60%

Al-rich Fe0.85Al0.15(1 0 0), (1 1 0) and (1 1 1) surface structures

Dai

Alyabyeva

Borghetti

et al. 2020

Applied Surface Science

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Based on previous photoemission findings, the influence of newly observed aluminum surface segregation at the low (110), (100) and (111) index surfaces of the A 2 body-centered Fe 0.85 Al 0.15 random alloy is explored. Scanning Tunneling Microscopy, Low-Energy Electron Diffraction and Grazing-Incidence X-Ray Diffraction are combined to explore surface structures and topographies. The formation of a surface composition close to the B 2 Fe 0.5 Al 0.5 occurs with the appearance of (i) a long-range pseudo-hexagonal incommensurate superstructure with a periodicity of ∼ 18Å on the (110) surface, (ii) a (1 × 1) termination on the (100) surface and (iii) a intense vicinal faceting of the (111) surface in the form of triangular pits.

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Section: Introductionsupporting

confidence: 60%

Al-rich Fe0.85Al0.15(1 0 0), (1 1 0) and (1 1 1) surface structures

Dai

Alyabyeva

Borghetti

et al. 2020

Applied Surface Science

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“…The basic phenomena of aluminium depletion by preferential sputtering and the recovery of the overall surface composition upon thermal annealing are well known for transition metal aluminide surfaces, as e.g. reported for FeAl [3,5,9,15], CoAl [16,17], and NiAl [18][19][20][21][22][23] surfaces. For the samples investigated in this work, this behaviour is illustrated in figure 4 by displaying the dependence of the above-defined Auger ratio r(Al/Fe) on the annealing temperature, starting with the temperature of sputtering (400 K).…”

Section: Structural Development Towards Equilibriummentioning

confidence: 99%

Equilibration of stoichiometrically distorted Fe_1-xAl_x(100) surfaces

Meier¹,

Blüm²,

Hammer³

et al. 2001

J. Phys.: Condens. Matter

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The correlation between segregation kinetics and the geometric and chemical structure of iron-rich Fe 1−x Al x (100) surfaces was investigated for four samples with different bulk stoichiometries (x = 0.03, 0.15, 0.30, 0.47) using quantitative low-energy electron diffraction (LEED) and Auger electron spectroscopy (AES). After being largely depleted of Al through preferential sputtering, the surfaces were annealed in a stepwise fashion. Auger signals as well as LEED patterns and intensity spectra were recorded for the transient phases which developed after each step, so monitoring the surfaces' return to equilibrium by means of aluminium segregation. They were used as fingerprints for comparison to the corresponding data of the equilibrium phases which had been analysed quantitatively in earlier investigations. It appears that transient phases of a sample with a certain bulk Al concentration can be identified with equilibrium phases of samples with lower bulk Al content. In other words, the structure of the surface slab accessible by means of LEED and AES is dictated by the actual intermediate slab stoichiometry in accordance with the bulk phase diagram and prevailing local quasi-equilibrium. The intermediate structures are metastable in the sense that the full equilibration of the crystal is kinetically limited by long-range mass transport from the bulk. In contrast, the top layer is always aluminium rich in accordance with the full equilibrium with the surface slab. So, the kinetics observed is dominated by the equilibration between the surface slab and the bulk, a feature possibly applying generally for stoichiometric equilibration in surfaces.

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“…33,34 Presumably, this is because the Al-Ni bond is much stronger than the Al-Ag or Ni-Ag bond, as reflected in the thermody-namic data for the respective alloys. [35][36][37] Thus, alloying is not anticipated in the present work, wherein Ag is deposited at 200 and 300 K. Second, the low surface energy of Ag usually leads the first few layers to "wet" the substrate, although strain can trigger three-dimensional growth in higher layers ͑Stranski-Krastanov growth͒. An example of the latter is Ag on W͑110͒.…”

Section: Introductionmentioning

confidence: 99%

Scanning tunneling microscopy and density functional theory study of initial bilayer growth of Ag films on NiAl(110)

et al. 2007

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Scanning tunneling microscopy (STM) studies of the deposition of Ag on bcc NiAl(110) in the temperature range from 200 to 300 K reveal an initial bilayer growth mode. In this regime, which encompasses at least the first two levels of bilayer islands, the film appears to have an fcc Ag(110)-like structure. Selection of this structure reflects an almost perfect lateral match between the Ag(110) and NiAl(110) lattice constants. Density functional theory (DFT) analysis of supported Ag films with an ideal fcc(110) structure on NiAl(110) indicates that the bilayer growth mode is promoted by a quantum size effect. However, the system does not exhibit perfect Ag(110) film growth. STM analysis reveals that the tops of Ag islands are decorated by a ripple structure even in the initial levels of growth and also shows a deviation from Ag(110)-like bilayer growth to Ag(111)-like monolayer growth for thick films. DFT analysis is also applied to provide some insight into the observed deviations from perfect Ag(110) film structure.

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Segregation phenomena on surfaces of the ordered bimetallic alloy FeAl

Cited by 40 publications

References 30 publications

Al-rich Fe0.85Al0.15(1 0 0), (1 1 0) and (1 1 1) surface structures

Al-rich Fe0.85Al0.15(1 0 0), (1 1 0) and (1 1 1) surface structures

Equilibration of stoichiometrically distorted Fe_1-xAl_x(100) surfaces

Scanning tunneling microscopy and density functional theory study of initial bilayer growth of Ag films on NiAl(110)

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Segregation phenomena on surfaces of the ordered bimetallic alloy FeAl

Cited by 40 publications

References 30 publications

Al-rich Fe0.85Al0.15(1 0 0), (1 1 0) and (1 1 1) surface structures

Al-rich Fe0.85Al0.15(1 0 0), (1 1 0) and (1 1 1) surface structures

Equilibration of stoichiometrically distorted Fe1-xAlx(100) surfaces

Scanning tunneling microscopy and density functional theory study of initial bilayer growth of Ag films on NiAl(110)

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Equilibration of stoichiometrically distorted Fe_1-xAl_x(100) surfaces