Representation Reaction Abilities of Structural Units and Related Thermodynamic Properties in Fe–P Binary Melts Based on the Atom–Molecule Coexistence Theory

Abstract

A thermodynamic model for calculating the mass action concentrations of structural units in FeÀP binary melts based on the atomÀmolecule coexistence theory, i.e., AMCTÀN i model, has been developed and verified through comparing with the reported activities of both P and Fe in FeÀP binary melts with mole fraction x P of P <0.33 in a temperature from 1406 K to 1973 K. The calculated mass action concentration N P of P or N Fe of Fe has a very good 1:1 corresponding relationship with the reported activity a R,P of P or a R,Fe of Fe relative to pure liquid P(l) or Fe(l) as standard state, and can be applied to substitute the measured activity a R,P of P or a R,Fe of Fe in FeÀP binary melts. The Raoultian activity coefficient g 0 P of P and g 0 Fe of Fe in the infinitely dilute solution of FeÀP binary melts in a temperature from 1406 K to 1973 K have been determined from the calculated mass action concentrations N i of structural units in FeÀP binary melts. The activity a R,i , a %,i , and a H,i of P or Fe relative to three standard states have been obtained. The values of the first-order activity interaction coefficient e i i or e i i or h i i of P and Fe related with activity coefficients g i or f %,i or f H,i of P and Fe in FeÀP binary melts are also determined.