Activities in liquid Fe-V-O and Fe-B-O alloys

Abstract

The activities in liquid Fe-V-0 and Fe-B-O alloys have been determined using the following galvanic cells Cr-Cr2O3(s) | ZrO2(CaO) | Fe-V-O (l, saturated with oxide) Cr-Cr2O3(s) | ThO2(Y2O3) | Fe-V-O (l, saturated with oxide) Cr-Cr2O3(s) | ZrO2(CaO) | Fe-B-O (l, B2O3 saturated with Al2O3) The solubility of oxygen in Fe-V alloys at 1600°C decreases with increasing vanadium content to a minimum of about 180 ppm at 3 wt pct V, and then increases to over 4000 ppm at 36.3 wt pct V. Vanadium was found to decrease the activity coefficient of oxygen and the value of the interaction coefficient eoV at infinite dilution of vanadium is -0.14. The activity of vanadium was calculated from the measured electromotive force, and log γv was found to be represented well by the quadratic formalism for Nv < 0.4: log γV = -0.70N2Fe -0.30 At 1550°C boron decreases the solubility of oxygen down to about 80 ppm at 0.67 wt pct B in Fe-B melts in equilibrium with B2O3 saturated with A12O3 (NAl2 O3 = 0.087). The boron deoxidation product, ’K′ = (wt pct B)2(wt pct 0)3 at infinite dilution of boron is 4.4 × 10-9 and 1.5 × 10-8 at 1550° and 1600°C, respectively. Boron decreases the activity coefficient of oxygen in liquid iron, and the value of the interaction coefficient eoB is -2.6 at infinite dilution of boron. The activity coefficient of boron at infinite dilution (γ°B) is 0.083 at 1550°C relative to solid boron.