Thermodynamic Interaction between Chromium and Phosphorus in High Cr Containing Liquid Iron

Abstract

Thermodynamic interaction between chromium and phosphorus in liquid iron was studied using the slag/metal equilibration technique to measure the equilibrium phosphorus distribution between liquid slags and carbon saturated Fe-Cr-P alloys containing chromium up to 20 mass% in the temperature range from 1 573 K to 1 723 K. The phosphate capacities, CPO43- of CaO-CaF2 and CaO-CaF2-Al2O3 slags at different temperatures were separately determined using carbon saturated liquid Fe P alloys under a CO atmosphere. The carbon solubility in liquid iron, which is known to have a large effect on phosphorus, was also determined as a function of chromium and phosphorus concentration. Using the Wagner's interaction parameter formalism, the experimental results were thermodynamically analyzed to determine the specific effects of phosphorus and chromium on phosphorus as their interaction parameters in liquid iron:

e(P)(P) = 0.054 (+/- 0.005), r(P)(P) = 0 (P ˂= 4 mass%, 1 573 K - 1 723 K)

e(P)(Cr) = 0, r(P)(Cr) = 0 (Cr ˂= 20 mass%, 1 623 K - 1 723 K)