Regular solution 2 S.J.T.U. Phase Transformation and Applications Page 16/30 In the case of regular solutions Gibbs free energy of mixing is symmetrical around the mid-point composition 0）--2w-0 2 T T←→XB C1+a2 0 8,30.25 0.5 0759,4 Above Tc Tc=@2R 绍→ Figure 9.14 The miscibility gap in solid A-B solutions. The A and B are completely miscible Below Tc The solution separates into two separate phases At points under the miscibility gap,the phase compositions vary with temperature SJTU Thermodynamics of Materials Spring2007©X.J.Jin Lecture 16 Phase Diagram IlPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2007 © X. J. Jin Lecture 16 Phase Diagram II Page 16/30 In the case of regular solutions Gibbs free energy of mixing is symmetrical around the mid-point composition 0)21( 1 ln =−+⎟⎟⎠⎞ ⎜⎜⎝⎛ − = ⎟⎟⎠⎞ ⎜⎜⎝⎛ ∂∂ B B B B T M x x x RT xG ϖ Above Tc The A and B are completely miscible B ↔ xT Regular solution 2 Below Tc The solution separates into two separate phases At points under the miscibility gap, the phase compositions vary with temperature R TC 2 =ϖ