Study on mechanism of iron reduction in magnesium alloy melt

This article studies the mechanism of iron reduction in magnesium alloy melt by investigating the iron concentrations in different parts in the melt with different holding time. The iron concentrations at the top, the center and the bottom of the melt are measured with the holding time of 300, 1800 and 7200 s. The elements in the sludge settling down in the crucible are also determined by ICP. With the increasing holding time, the iron content in the upper part of the melt decreases and that in the lower part of the melt increases. And the iron content in the sludge increases rapidly. The iron concentrations in the melt and the sludge change little with longer holding time than 1800 s. Among the three iron reduction agents B₂O₃, MnCl₂ and TiO₂, B₂O₃ has the highest iron reduction efficiency (IRE). IRE of B₂O₃ is as two times and five times as IRE of MnCl₂ and IRE of TiO₂ respectively. Formation of FeB and settling of it into melting sludge are believed to be the primary mechanism of iron reduction by B₂O₃ processing. The mechanism of iron reduction in magnesium melt by MnCl₂ or TiO₂ processing is studied by thermodynamic analysis. Formation of substance containing MnFeAl or TiFe with high density and high melting point and settling of them into melting sludge are suggested to be the mechanism of iron reduction by MnCl₂ or TiO₂ processing.