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

摘要

A 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-N, 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 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 Fe-P binary melts. The Raoultian activity coefficient γ_p~0 of P and γ_(Fe)~0 of Fe in the infinitely dilute solution of Fe-P binary melts in a temperature from U06 K to 1973 K have been determined from the calculated mass action concentrations N_i of structural units in Fe-P 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 ε_i~i or e_i~i or h_i~i of P and Fe related with activity coefficients γi or f_(%,i) or f_(H,i) of P and Fe in Fe-P binary melts are also determined.