Mn-induced Refining Poisoning Effect in Al-Si-Mn Alloys
With the gradual increase in amount of recycled aluminum,Mn element,which is used to improve the mor-phology of Fe phase,plays an increasingly important role in aluminum alloys.However,Mn-induced refining poison-ing effect occurs in Al-Si-Mn(ASM)alloys with Al-Ti-B alloy addition,of which the degree deepens with the increase of Mn(or Si)content.The mechanism of Mn poisoning was revealed by means of optical microscopy,scan-ning electron microscopy and Pandat software.The results indicate that the primary solidification phase of Al15FeMn3Si2 is observed with higher Mn content in ASM alloys,which covers the free titanium particles in the alumi-num alloy melt,leading to the miss of nucleation substrate and resulting in the poisoning phenomenon.A new process was proposed to regulate the primary phase in ASM alloys with a small amount of Ti with assistance of Al-Ti-C-B(Al-TCB)seed alloy to effectively alleviate Mn-induced refining poisoning.