Thermodynamic activity(2) S.J.T.U. Phase Transformation and Applications Standard state not reference state In liquid solutions and solid solutions the pure materials at one atmosphere pressure and specified crystal structure. Solid solution of iron and nickel The pure iron (bec or fec)and pure nickel are chosen as the standard state. Gi-Gipure =G:-Gj=RTlna dG;RTd(Infi) Ideal solution: The fugacity of component i is equal to the mole fraction of component i multiplied by the fugacity of i in the pure state. fi=xifP SJTU Thermodynamics of Materials Spring 2007 ©X.J.Jin Lecture 11 Solution IPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2007 © X. J. Jin Lecture 11 Solution I i i i purei i , =−=− RTGGGG lnα D p ii i = fxf Thermodynamic activity (2) Standard state / not reference state In liquid solutions and solid solutions the pure materials at one atmosphere pressure and specified crystal structure. Solid solution of iron and nickel The pure iron (bcc or fcc) and pure nickel are chosen as the standard state. i = fRTdGd i)(ln Ideal solution: The fugacity of component i is equal to the mole fraction of component i multiplied by the fugacity of i in the pure state