X-RAY-ANALYSIS OF MAGNESIUM DIFFUSION TOW ARDS THE SURFACE OF AN ASGM-0.7 ALUMINUM-ALLOY MADE BY POWDER-METALLURGY

The aim of this paper was to characterize the magnesium oxide film whi ch forms on the surface of the aluminum alloy ASGM 0.7 during thermal treatments. Grazing X-ray diffraction revealed an increase in the MgO content in the surface, particularly for high temperature thermal trea tments. The concentration ratio (C-MgO/C-Al) for treatments of 1 and 6 hours at 540 degrees C was determined as a function of the mean thick ness of irradiated material. The MgO ratio is maximum in a 1,2 mu m th in layer, in the immediate vicinity of the surface (15,1% for a treatm ent of 6 hours at 540 degrees C).