9.2 The Lever Rule(1) S.J.T.0. Phase Transformation and Applications Page 20/36 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 thethe composition. The relative quantities or fractions of liquid B and solid using a mass balance. Liquid XB=FXB+FsXBs F(XBI-XB)=Fs(XB-XB.s) L+S F=fraction liquid Fs=fraction solid (XB-XB.S） (XBI-XB) F+Fs=1,and a mass balance A B E XB-XB.s XB.S XB XB.1 F- XB-XBs XB→ F XBI-XB XBI-XB.S Fig.9.4 Illustration of the lever rule. SJTU Thermodynamics of Materials Fall 2011 ©X.J.Jin Lecture 14 Phase diagram IPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2011 © X. J. Jin Lecture 14 Phase diagram I Page 20/36 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 ( ) B B,S x − x ( ) B,l B x − x 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 , , B l B S B B s B B l S B s F x x F x x x F x F x − = − = + B l B B B s S x x x x F F − − = , 1 , B l B S B B s x x x x F , , , 1 − − = xB