Thermophysical properties of liquid industrial ferrochromium alloys

This paper analyses melting properties and density of liquid ferrochromium alloys with different carbon contents; from low-carbon (0.027 wt% C) to high-carbon (7.7 wt% C) ferrochrome with chromium content 68 -73 wt%. The experimental liquidus temperature decreased from 1943 K to 1687 K with increasing carbon content from 0.027 to 3.7 wt% and increased to 1945 K with further increase in carbon content to 7.7 wt%. Experimental density of liquid alloys at liquidus temperature was in the range 6.30-6.50 g/cm3 for alloys with 0.027-4.65 wt% C, and 6.16 g/cm3 for the alloy with 7.7 wt% C. Volumetric coefficients of thermal expansion were in the range of (0.9-1.4) × 10-4 K-1 for the studied alloys. Liquidus temperatures of alloys calculated using Thermo-Calc were significantly higher for alloys with 0.027-1.2 wt% C (up to 80 K), and were in a reasonable agreement with experimental data for alloys with higher carbon content. Calculated densities were lower than experimental data; volumetric coefficients of thermal expansion (0.3-0.4) × 10-4 K-1 were significantly lower. The density and molar volume of liquid ferrochromium alloys were also analysed using the model of interstitial solutions (stereochemical model developed by P. Gaskell). Molar volumes and volumetric coefficients of pure liquid iron and chromium are very close. Substitution of Fe for Cr does not change parameters of the interstitial model. Calculated molar volumes and densities of liquid ferrochromium alloys at 1873 and 1973 K are in agreement with experimental data.