Solidification characteristics of the Al-8.3Fe-0.8V-0.9Si alloy

Studies of solidification behavior have been conducted on cast AI-Fe-V-Si a lloys. The first phase to precipitate during solidification of an Al-8.3Fe- 0.8V-0.9Si alloy is Al3Fe(V,Si), which is isostructural with the Al3Fe phas e. Thereafter, the solidification proceeds through several invariant reacti ons. The final invariant reaction is associated with a pronounced arrest. T he temperature of this arrest is a function of the cooling rate and modific ation treatment, with magnesium added as an Al-20 pet Mg or Ni-20 pet Mg ma ster alloy. The coarse iron aluminide precipitates in a slow-cooled (>1 deg rees C/s) cast structure transform to a ten-armed, star-like morphology upo n chill casting the melt (cooling rate >10 degrees C/s) from 900 degrees C or upon water quenching from above 800 degrees C. Treatment with magnesium refines the morphology, size, and distribution of iron aluminide precipitat es in slow-cooled alloys.