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Surface reactions during rapid solidification and handling of Al5Mn2.5Cr powders
Author(s) -
Olefjord I.,
Nylund A.
Publication year - 1988
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.740120707
Subject(s) - relative humidity , hydroxide , oxide , aluminium hydroxide , aluminium , materials science , aluminium oxide , metallurgy , auger electron spectroscopy , humidity , layer (electronics) , atmospheric temperature range , chemistry , inorganic chemistry , composite material , physics , meteorology , nuclear physics , thermodynamics
Rapidly solidified Al powders were analysed in the as‐received condition, and after exposure in humid atmospheres, using ESCA and Auger spectroscopy. The composition of the powder is Al5Mn2.5Cr. It was produced by the ultra sonic gas atomization (USGA) technique. The cooling rate was in the range 10 5 –10 6 K s −1 . The surface of the as‐atomized powder is partly covered by aluminium oxide particles formed at high temperatures during atomization and by a thin uniform oxide film formed between the oxide particles. The thin film is formed at low temperatures during atomization and during handling of the powder. The average thickness of the oxide is 50 Å. The powders were exposed in humid atmosphere at 22°C for 1 day and for 1 week, at relative humidities of 60% and 80%. During the exposure, aluminium hydroxide is formed on the surface of the oxide. The thickness of the hydroxide layer increases with exposure time and the humidity. After exposure for 1 week in relative humidities of 60% and 80% the thicknesses of the hydroxide layers were 10 and 12 Å, respectively.