9.1 Freezing Point Depress4ion (4) S.J.T.U. Phase Transformation and Applications Page 4/30 The liquid solution is in equilibrium with 稀溶液的依数性 the pure solid, aA.L.pure =1 △G= L(T-T) T分X RTIn a1solution 主0 1.pure asolid=1 L(Tm-T)=-RTInXAJ.solmon ideal solution If T is close to the Tm In xA1.solution L(T-T) RT A XB→ B Melting point depression Fig.9.2 Plot of the activity of Aliqui L(T -T) △T=Tm-T at T<Tm.A versus composition. XB 二 ln(1-z）=-z small z 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 4/30 9.1 Freezing Point Depress4ion (4) Fig. 9.2 Plot of the activity of Aliquid at T < Tm,A versus composition. A B 1.0 a A (liquid) xB asolid=1 aA,l,pure=1 The liquid solution is in equilibrium with the pure solid, ln 0 )( , , + = − =Δ purel solutionl m m a a RT T TTL G If T is close to the Tm xRT ideal solution T TTL solutionlA m m ,, ln )( −= − ,, 2 )( ln m m solutionlA RT TTL x − −= 2 )( m m B RT TTL x − = zsmallzz m TTT −=− Δ = − )1ln( Melting point depression 稀溶液的依数性 ↔ xT