Density and Molar Volume of Liquid Iron Containing Nb

Abstract

Densities of liquid iron containing Nb up to 0.198 wt pct were measured with the modified sessile drop method in a temperature range from 1510 to 16108C. The densities decrease linearly with increase in temperature and increase with increase in niobium content. The thermal expansion coefficient of molten liquid containing Nb increases linearly with increase in niobium content. An equation for density of liquid iron containing niobium has been derived from the measured results as a function of temperature and niobium content as follows:rð10 3 kg m À3 Þ ¼ 7:03 þ 0:75 Â ½%Nb À ð7:54 þ 6:92 Â ½%NbÞ Â 10 À4 ðT À 1530Þ 1510 C T 1610 C; T in C The difference between the measured and calculated values is in the range of À0.26 to þ0.29 pct. The molar volume of liquid iron containing Nb at the same temperature decreases with increase in niobium content. The partial molar volume of niobium in liquid iron decreases with increase in temperature, while that of iron increases with temperature. The densities calculated with the partial molar volumes are in good agreement with the measured ones for the iron-niobium binary alloys.