SURFACE-ANALYSIS OF POWDER ALUMINUM-ALLOY

Electron Spectroscopy for Chemicals Analysis (ESCA) was used to determ ine the concentration of elements in the surface of aluminum alloy of the type ASGM 0.7. Aluminum, silicon and magnesium can exist either in the form of element or element oxide. It was shown that the oxides ar e amorphous. Subsequently, the increase in magnesium oxide following a heat treatment was determined. The increase in thickness was studied for specimens heated at 410 and 535 degrees C. It appears that with in creasing temperature the proportion of MgO increases and also the vale ncy of the bonds is higher than for compact material. Argon ion beam m illing was used to remove surface layer enabling sub-surface analysis of the powder. The ratio {I-MgO/(I-AlO + I-Al)} (I refers to integrate d intensity of photoelectronic peaks) was determined using an empirica l formula. It approaches a constant value asymptocally with increasing depth. The ratio is 5% for compacted material heated at 410 degrees C . It was shown that alumina exists in the amorphous state and does not crystallize to gamma-Al2O3 on heating. The increase in MgO could be d ue to the slow sublimation of magnesium.