We studied the influence of mechanical activation (MA) of alumina to modify its crystal lattice and on the dissolution rate in molten fluorides during electrolysis . The changes in phase composition - education x-ray amorphous alumina after MA mills : planetary and vibratory. Studied structural changes in mechanically activated oxide phases such as alumina example, α-Al2O3 . The images confirmed that the dominant slip plane in the structure of corundum is the basal plane {111}.