Solid Solubility of Selenium in Fe-3.25% Silicon Alloy

Abstract

The solubility of selenium in Fe-3.25% silicon alloy was determined by equilibrating the alloy with a gaseous mixture of H₂ and H₂Se. The composition of the gas mixture, was controlled by adjusting thetemperature of the following reaction:
FeSe (s or l) +H₂ (g) _??_Fe (s) +H₂Se (g)
The results obtained are as follows:
1) The solidus and the liquidus temperature of FeSe were found to be 1270° and 1318°K, respectively. Equilibrium constant, K=PH₂Se/PH₂, was determined to be
logK=-3760/T+0.15 (T<1270°K)
logK=-2200/T+0.53 (1318°K<T)
2) In the absence of manganese, the solubility of selenium was found to be 0.016% (in wt%) at 1200°C, 0.022% at 1250°C and 0.061% at 1300°C. In the presence of 0.05% manganese the solubility ofselenium was found to be 0.014% at 1200°C, 0.017% at 1250°C and 0.041% at 1300°C. In the presenceof 0.10% manganese the selenium solubility was 0.011% at 1200°C, 0.015% at 1250°C and 0.030% at1300°C.
3) The solubility product of manganese and selenium was found to be strongly dependent on manganesecontent in the range of manganese levels measured.