The vapor pressure of P on liquid Fe-P-j (j= C, Si, Al, or B) alloys has been measured by the transportation method at 1673 K.
The results obtained were treated by the model of interstitial solution proposed by J. CHIPMAN, and the effect of alloying elements on the activity coefficient of P in liquid iron was determined by assuming C and B as interstitial elements and Si and Al as substitutional ones respectively.
The interaction parameters are summarized as follows:
ε^C_P=(∂1nγ_P/∂X_c)X_Fe→1=5.43±0.67
ε^Sl_P=(∂1nγ_P/∂X_si)X_Fe→1=7.68±0.44
ε^Al_P=(∂1nγ_P/∂X_Al)X_Fe→1=3.57±0.33
ε^B_P=(∂1nγ_P/∂X_B)X_Fe→1=1.49±0.16