Contents of Today S.J.T.0. Phase Transformation and Applications Page 1/36 Review previous Freezing Point Depression The lever rule Simple eutectic diagram Cooling curves Review of today SJTU Thermodynamics of Materials Fall 2011 ©X.J.Jin Lecture 14 Phase diagram I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2011 © X. J. Jin Lecture 14 Phase diagram I Page 1/36 Contents of Today Review previous Freezing Point Depression The lever rule Simple eutectic diagram Cooling curves Review of today
Review of Last S.J.T.U. Phase Transformation and Applications Page 2/36 ·Phase rule:相律 ·Phase diagram:相图 One-component systems SJTU Thermodynamics of Materials Fall 2011 ©X.J.Jin Lecture 14 Phase diagram I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2011 © X. J. Jin Lecture 14 Phase diagram I Page 2/36 Review of Last • Phase rule : 相律 • Phase diagram : 相图 • One-component systems
吉布斯相律 S.J.T.0. Phase Transformation and Applications Page 3/36 吉布斯相律是处于热力学平衡状态的系统中自 由度与组元和相数之间关系的规律 基本概念包括相、组元和自由度等。 - 相为系统中性质与成分均匀的一部分；相平衡指的 是在多相体系中所有相的强度性质均相等，体系的 性质不会自发地随时间变化的状态即相平衡状态； - 组元为决定各平衡相的成分，而且是可以独立变化 的组分（元素或化合物)； 自由度是可以在一定范围内任意改变而不引起任何 相的产生与消失的最大变量数。 F=C-P+2 SJTU Thermodynamics of Materials Fall 2011 ©X.J.Jin Lecture 14 Phase diagram I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2011 © X. J. Jin Lecture 14 Phase diagram I Page 3/36 吉布斯相律 • 吉布斯相律是处于热力学平衡状态的系统中自 由度与组元和相数之间关系的规律。 • 基本概念包括相、组元和自由度等。 –相为系统中性质与成分均匀的一部分；相平衡指的 是在多相体系中所有相的强度性质均相等，体系的 性质不会自发地随时间变化的状态即相平衡状态； –组元为决定各平衡相的成分，而且是可以独立变化 的组分（元素或化合物）； –自由度是可以在一定范围内任意改变而不引起任何 相的产生与消失的最大变量数。 F = C − P + 2
局限性 S.J.T.U. Phase Transformation and Applications Page 4/36 但相律只是对可能存在的平衡状态的一 个定性描述。它可以给出一个相图中可 能有些什么点、线和区，却不能给出这 些点、线和区的具体位置。 SJTU Thermodynamics of Materials Fall 2011 ©X.J.Jin Lecture 14 Phase diagram I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2011 © X. J. Jin Lecture 14 Phase diagram I Page 4/36 • 但相律只是对可能存在的平衡状态的一 个定性描述。它可以给出一个相图中可 能有些什么点、线和区，却不能给出这 些点、线和区的具体位置。 局限性
单组分系统 S.J.T.0. Phase Transformation and Applications Page 5/36 ·相律分析 F=C-P+2 C=1 P=1,F=2 P≥1；F≥0 P=2,F=1 P=3,F=0 ·物态转变方程式 dP△H N.H 气固或气液 dT TAV P=Aexp RT △H△T 固液 △P= =K·△T AV T SJTU Thermodynamics of Materials Fall 2011 X.J.Jin Lecture 14 Phase diagram I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2011 © X. J. Jin Lecture 14 Phase diagram I Page 5/36 单组分系统 • 相律分析 • 物态转变方程式 C =1 3, 0 2, 1 1, 2 = = = = = = P F P F F = C − P + 2 P F P ≥1;F ≥ 0 T V H dT dP β α β α Δ Δ = ⎟⎟⎠⎞ ⎜⎜⎝⎛ Δ = − RTH P A βα exp K T T T V H P = ⋅Δ Δ Δ Δ Δ = 1 β α β α 气固或气液 固液
S.J.T.0. Phase Transformation and Applications Page 6/36 45.7K 3×105Pa Liquid ainssald Solid B(F=1 菱形 液 A Gas 单斜 Triple point (F=2) R 3.33 M' 1,33 R Temperature→ 368.6 386392 Figure 8.1 Phase diagram for water (one component).In the T/K phase diagram for water,the solid-liquid equilibrium line slopes up and to the left from the triple point because the volume change upon solidification is positive.In most mate- 图6-4硫系相图 rials.the volume change upon solidification is negative,and the solid-liquid equilibrium line slopes up and to the right. SJTU Thermodynamics of Materials Fall 2011 ©X.J.Jin Lecture 14 Phase diagram I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2011 © X. J. Jin Lecture 14 Phase diagram I Page 6/36
S.J.T.0. Phase Transformation and Applications Page 7/36 熔体 17132 、1620元 ~1600℃ 赛熙 石英玻璃 B'IC" 870℃ 方石英 a-方石英 1470℃ a-鳞石英 a-石英 B 180-270℃ 163℃ 573℃ B方石英 鳞石英足鲸石英 a-鳞石英 A B-方石英 B-鳞石英 B-石英 石英玻璃 a石英 阜石英 117℃ Y-鳞石英 120163230 573 870 1350147016701713 1600 T/c 图6-5Si02系相图 SJTU Thermodynamics of Materials Fall 2011 ©X.J.Jin Lecture 14 Phase diagram I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2011 © X. J. Jin Lecture 14 Phase diagram I Page 7/36
Phase diagram for pure Fe S.J.T.0. Phase Transformation and Applications Page 8/36 3500 3000 Melt 00 2000 1500 1000X 500-a 1 0 20 40 60 80 100 120 Pressure《GPa) SAXENA,S.K.,G.SHEN and P.LAZOR,1993.Science,260,1312. SJTU Thermodynamics of Materials Fall 2011 ©X.J.Jin Lecture 14 Phase diagram I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2011 © X. J. Jin Lecture 14 Phase diagram I Page 8/36 Phase diagram for pure Fe
Nomenclature S.J.T.0. Phase Transformation and Applications Page 9/36 Freezing Point Depression:擬固点下降 ·The lever rule:杠杆定量 。 Simple eutectic diagram:简单共晶相图 Cooling curves:冷却曲线 SJTU Thermodynamics of Materials Fall 2011 ©X.J.Jin Lecture 14 Phase diagram I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2011 © X. J. Jin Lecture 14 Phase diagram I Page 9/36 Nomenclature • Freezing Point Depression:凝固点下降 • The lever rule：杠杆定量 • Simple eutectic diagram：简单共晶相图 • Cooling curves：冷却曲线
Binary Phase Diagrams S.J.T.0. Phase Transformation and Applications Page 10/36 In condensed systems,modest variations in pressure do not appreciably alter phase relationship Phase rule for condensed system F=C-P+1 It is possible to plot phase stability regions for two-component(binary) systems in two dimensions.C=2.F=3-P Composition on abscissa(horizontal axis) Temperature on the ordinate(vertical axis) T-x SJTU Thermodynamics of Materials Fall 2011 ©X.J.Jin Lecture 14 Phase diagram I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2011 © X. J. Jin Lecture 14 Phase diagram I Page 10/36 Binary Phase Diagrams Phase rule for condensed system In condensed systems, modest variations in pressure do not appreciably alter phase relationship F = C − P +1 It is possible to plot phase stability regions for two-component (binary) systems in two dimensions. C=2, F=3-P Composition on abscissa (horizontal axis) Temperature on the ordinate (vertical axis) T - x