During heat‐treatment of Mg‐containing Al‐based alloys, the Mg concentration changes considerably. As compared to the pure material significant surface corrosion is observed for the air heattreated alloy. In vacuum heat treatment the Mg content of the surface layer increases considerably. Initially metallic Mg is detected on the surface which, however, becomes oxidized later on. On the basis of the investigations one has to assume that the process is not a simple diffusion mechanism only. A new conception is formed for the process according to which it is controlled by the breaking up of the Al2O3 barrier layer by Mg.

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The density of electron states of binary alloys of transitional elements with short-range order is found using the coherent potential approximation. On the base of these calculated values the contribution of the band structure energy to the configurational part of the total energy is determined and the equilibrium value of the short-range order parameter on the first coordination sphere is evaluated. I'he order parameters obtained for most the considered systems agree in sign with the experimental data.Die Dichte der Elektronenzustande binarer tfbergangsmetallegierungen mit Nahordnung wird mittels der Naherung des koharenten Potentials gefunden. Auf der Grundlage dieser berechneten Werte wird der Beitrag der Bandstrukturenergie zum Konfigurationsanteil der Gesamtenergie bestimmt und der Gleichgewichtswert des Nahordnungsparameters von der ersten Koordinationssphare berechnet. Die erhaltenen Ordnungsparameter befinden sich fur die meisten betrnchteten Systeme im Vorzeichen in Vbereinstimmung mit den experimentellen Werten.