Effect of ultrafine powders on the structural formation processes and mechanical properties of Al–7%Si alloy

The multi-component system interaction mechanisms associated with ultrafine powders (TiO[2] and ZrO[2]) and fluorine-containing salts (K[2]ZrF[6], Na[3]AlF[6] and Na[5]Al[3]F[14]) with the Al-7%Si melt are studied. The formation of a multi-phase system with a high concentration of crystallization centres (N≈7·10{12} U/cm{3}) was identified. We experimentally show that the injection of an ultrafine powders modifying mixture containing refractory metal oxides and fluorine-containing salts into a Al-7%Si melt leads to a significant reduction in the a silicon plate size (by 1.5 times) and the Fe-containing phases (by 4 times). An equal distribution of the eutectic phase ([alpha]-Al+[beta]-Si) is established in the Al-7%Si alloy. As a result of microstructural changes when the modifying mixture was injected, a factor of 2 increase in the Al-7%Si alloy ductility was observed