INFLUENCE OF COMPLEX MODIFICATION ON THE FORMATION OF IRON-CONTAINING PHASES IN THE A380 ALLOY

The work is devoted to the study of structural-phase characteristics, in particular - the modification of iron-containing phases in Al-Si-Cu system cast aluminum alloys after adding microalloying elements and modifiers (Co, Cr, V and Mo) to their composition separately and in various combinations with each other. The widespread commercial alloy A380 was chosen as a modeling material for the research. The prospects of using complex modification principles, which makes it possible to reduce the content of modifiers to 0.5 wt. % are shown. Such concentration of modifying additives is 2−3 times lower in comparison with similar studies. It is also shown that the best grain refinement and microstructure homogenization indicators were achieved by modifying the alloy with cobalt, vanadium and molybdenum. It was found that molybdenum is more effectively grain refiner, but it makes iron-containing phases less compact and promotes their formation by the primary mechanism even with single-component modification. The negative aspects of the molybdenum influence are enhanced by the addition of chromium, but they can be eliminated by the addition of vanadium and cobalt. Alloy modification according to the schemes Co+V, V+Mo, Cr+Co+Mo, V+Co+Mo and Co+Cr+V+Mo showed the highest efficiency of the influence on the structural-phase state of the A380 alloy. In particular, the formation of β-Al5FeSi-type phases was almost completely eliminated and significant modification and refinement of the α-AІ15(Fe,Mn,Me)3Si2-type phases, the sizes of which usually did not exceed 10…15 μm, was achieved. With an increase in the number of modifiers, especially vanadium and molybdenum, more signs of the iron-containing phases by the primary mechanism formation were observed, while maintaining their small sizes. It is shown that by varying the set and content of modifiers, it is possible make influence on the structure and phase formation of the Al−Si−Cu system alloys.