9.2 The Lever Rule (1) S.J.T.0. Phase Transformation and Applications Page 5/34 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. Liquid F=fraction liquid Fs=fraction solid L+S F Fs=1,and a mass balance FXB-XBs F= XB-XB.s (XB-XB,s） FS XBI-XB XBI-XB.S A B XB.S XB XB.1 XB→ Fig.9.4 Illustration of the lever rule. SJTU Thermodynamics of Materials Fall 2011 X.J.Jin Lecture 15 Phase Diagram llPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2011 © X. J. Jin Lecture 15 Phase Diagram II Page 5/34 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. Fig. 9.4 Illustration of the lever rule. Fl=fraction liquid FS=fraction solid Fl+ FS=1, and a mass balance 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 − − = B xB A Tm T xB,S xB xB,l T1 Fig. 9.4 Illustration of the lever rule. B xB A Tm Liquid xB,l L+S xB,S xB ( ) B B,S x − x ( ) B,l B x − x Fig. 9.4 Illustration of the lever rule