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Surface segregation and oxidation studies of AlBe alloys
Author(s) -
Ahmad M.,
Blakely J. M.
Publication year - 1987
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740100206
Subject(s) - annealing (glass) , crystallite , single crystal , materials science , crystallography , analytical chemistry (journal) , basal plane , chemistry , metallurgy , chromatography
Surface segregation and oxidation of AlBe alloys have been studied using the LEED‐AES technique. Results obtained from one polycrystalline sample and three single crystals with (001), (011) and (111) orientations show no segregation of Be to the clean Al surface. The annealing temperatures ranged from 300 °C to 600 °C for a few minutes to a few hours. Results from the polycrystalline sample suggest that in the presence of oxygen or Al 2 O 3 on the surface, Be diffuses to the surface during annealing (at 400 °C or above) to form BeO and reduces Al 2 O 3 . The difference in the free energies of formation of the bulk BeO and Al 2 O 3 favors this reaction. A one‐to‐one correspondence has been found between the surface coverage of BeO formed to that of Al 2 O 3 present prior to annealing the sample. The three single crystals had much less Be in the bulk and this affects the reduction reaction by limiting the rate of Be diffusion to the surface. LEED investigation for the (111) oriented crystal showed that BeO grows as the (0001) basal plane on the Al(111) surface. The magnitude of the misfit between unrelaxed Al(111) and BeO(0001) as measured from the relative positions of superlattice beams indicate some compression or expansion in the interface region.