9.2 The Lever Rule (1) S.J.T.U. Phase Transformation and Applications Page 5/30 In a two-phase region of a condensed system,if the overall composition is given,the quantities of the various phases can be calculated,beside to the the composition. The relative quantities or fractions of liquid and solid using a mass balance. 人 Liquid xg=FXBI+FsxB.s F(xBI-xB)=Fs(xB-XB.s) L+S F=fraction liquid Fs=fraction solid (XB-XB.S) F+Fs=1,and a mass balance A B FXB-XB.s XB-XB.s XB.S XB XB.I F XB→ Fs XBI-XB XBI-XB.S Fig.9.4 Illustration of the lever rule. SJTU Thermodynamics of Materials Spring 2007 ©X.J.Jin Lecture 16 Phase Diagram llPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2007 © X. J. Jin Lecture 16 Phase Diagram II Page 5/30 9.2 The Lever Rule (1) In a two-phase region of a condensed system, if the overall composition is given, the quantities of the various phases can be calculated, beside to the the composition. B xB A Tm T Liquid xB,l L+S xB,S xB T1 )( ,SBB − xx )( , BlB − xx Fig. 9.4 Illustration of the lever rule. The relative quantities or fractions of liquid and solid using a mass balance. Fl=fraction liquid FS=fraction solid Fl+ FS=1, and a mass balance )()( ,1 , ,1 , sBBSBlB B sBSlB xxFxxF xFxFx −=− = + BlB sBB S xx xx F F − − = , 1 , SBlB sBB xx xx F ,, , 1 − − =