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

Abstract

AbstractA thermodynamic model for calculating the mass action concentrations of structural units in Fe–P binary melts based on the atom–molecule coexistence theory, i.e., AMCT–Ni model, has been developed and verified through comparing with the reported activities of both P and Fe in Fe–P binary melts with mole fraction xP of P <0.33 in a temperature from 1406 K to 1973 K. The calculated mass action concentration NP of P or NFe of Fe has a very good 1:1 corresponding relationship with the reported activity aR,P of P or aR,Fe of Fe relative to pure liquid P(l) or Fe(l) as standard state, and can be applied to substitute the measured activity aR,P of P or aR,Fe of Fe in Fe–P binary melts. The Raoultian activity coefficient of P and of Fe in the infinitely dilute solution of Fe–P binary melts in a temperature from 1406 K to 1973 K have been determined from the calculated mass action concentrations Ni of structural units in Fe–P binary melts. The activity aR,i, a%,i, and aH,i of P or Fe relative to three standard states have been obtained. The values of the first‐order activity interaction coefficient or or of P and Fe related with activity coefficients γi or f%,i or fH,i of P and Fe in Fe–P binary melts are also determined.