Contents of Today S.J.T.U. Phase Transformation and Applications Page 1/45 Review Phase rule One-component systems etc. SJTU Thermodynamics of Materials Spring2010©X.J.Jin Lecture 14 Phase Rule
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2010 © X. J. Jin Lecture 14 Phase Rule Page 1/45 Contents of Today Review : Phase rule One-component systems etc
Nomenclature S.J.T.U. Phase Transformation and Applications Page 2/45 Phase:相 Component:组元 Degrees of freedom:自由度 Phase rule:相律 Phase diagram:相图 One-component system:单元系 SJTU Thermodynamics of Materials Spring2010©X.J.Jin Lecture 14 Phase Rule
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2010 © X. J. Jin Lecture 14 Phase Rule Page 2/45 Nomenclature Phase: 相 Component: 组元 Degrees of freedom: 自由度 Phase rule: 相律 Phase diagram: 相图 One-component system：单元系
Phase rule S.J.T.U. Phase Transformation and Applications Page 3/45 Thermodynamic stability of coexisting elements,compounds,and solution Equilibrium structure How many phases 所有多相平衡系统都遵循的普遍规律！ 描述平衡系统中相数、组分数以及影响系统状态的独立 可变因素（如温度、压力、组成等）的总数（称为自由 度数)之间的关系。 SJTU Thermodynamics of Materials Spring 2010 ©X.J.Jin Lecture 14 Phase Rule
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2010 © X. J. Jin Lecture 14 Phase Rule Page 3/45 Phase Rule Thermodynamic stability of coexisting elements, compounds, and solution Equilibrium structure How many phases 所有多相平衡系统都遵循的普遍规律！ 描述平衡系统中相数、组分数以及影响系统状态的独立 可变因素（如温度、压力、组成等）的总数（称为自由 度数）之间的关系
8.1 Phase 1 S.J.T.U. Phase Transformation and Applications Page 4/45 何谓相：物理、化学性质相同的均匀部分 相与相之间有明确界面，越过界面，性质突变 气相，无论多少，1相 液相，纯、溶液（均匀），1相 多种液体混合，溶解度，1,2,3， •固相，纯或原子/分子状态相互混合成固溶体，1相 一般体系中，多一种固体便多一个相 SJTU Thermodynamics of Materials Spring2010©X.J.Jin Lecture 14 Phase Rule
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2010 © X. J. Jin Lecture 14 Phase Rule Page 4/45 8.1 Phase 1 何谓相：物理、化学性质相同的均匀部分 相与相之间有明确界面，越过界面，性质突变 •气相，无论多少，1相 •液相，纯、溶液（均匀），1相 多种液体混合，溶解度，1，2，3，… •固相，纯或原子/分子状态相互混合成固溶体，1相 一般体系中，多一种固体便多一个相
独立组元/组分数 S.J.T.U. Phase Transformation and Applications Page 5/45 物种chemical species N 体系中每个可以单独分离出来并能独立存在 的化学均匀物质 C=N-R 例子：食盐水NaCl+H2O N=2 限制条件3仅限于同一相 独立组元，构成平衡体系所 中的物质，且不包括一 需的最少物种 相中各组元的摩尔分数 R,物种之间存在的独立关系数 之和为1这一条件 例子：N2,H2,NH3 彼此无关 •化学平衡 W2+3H2=2WH3 化学平衡十N2:H2起始浓度比=1：3 SJTU Thermodynamics of Materials Spring 2010 ©X.J.Jin Lecture 14 Phase Rule
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2010 © X. J. Jin Lecture 14 Phase Rule Page 5/45 独立组元/组分数 • 物种 chemical species N 体系中每个可以单独分离出来并能独立存在 的化学均匀物质 例子：食盐水 NaCl + H2O N=2 C N R 限制条件3仅限于同一相 中的物质，且不包括一 相中各组元的摩尔分数 之和为1这一条件 N2 3H2 2NH3 •独立组元，构成平衡体系所 需的最少物种 R，物种之间存在的独立关系数 例子：N2 ,H2 ,NH3 •彼此无关 •化学平衡 •化学平衡 ＋ N2 :H2起始浓度比＝1：3
Degrees of Freedom S.J.T.U. Phase Transformation and Applications Page 6/45 在一定范围内独立变动而不致破坏多相平 衡的强度因素（温度、压力和组成等）的 数目 ·不考虑相的数量， 表面及表面能 SJTU Thermodynamics of Materials Spring2010©X.J.Jin Lecture 14 Phase Rule
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2010 © X. J. Jin Lecture 14 Phase Rule Page 6/45 Degrees of Freedom • 在一定范围内独立变动而不致破坏多相平 衡的强度因素（温度、压力和组成等）的 数目 • 不考虑相的数量，表面及表面能
8.3 Specifying a System S.J.T.U. Phase Transformation and Applications Page 7/45 Intensive properties VAR:total number of variables to be specified AR=P(C-1)+2 C:components P:phase Not take account of following situations: ●Amount of each phase .Surfaces or surface energy SJTU Thermodynamics of Materials Spring2010©X.J.Jin Lecture 14 Phase Rule
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2010 © X. J. Jin Lecture 14 Phase Rule Page 7/45 8.3 Specifying a System Intensive properties VAR: total number of variables to be specified Not take account of following situations: •Amount of each phase •Surfaces or surface energy VAR P(C 1) 2 C: components P: phase
8.4 Equilibrium Conditions S.J.T.U. Phase Transformation and Applications Page 8/45 Equilibrium conditions: The chemical potential (partial molar Gibbs free energy)of a component must be the same throughout the system Intensive properties 4=4=4=44=.=4 the chemical potential of component i in phase p The total number of relationship REL=C(P-1) SJTU Thermodynamics of Materials Spring 2010 ©X.J.Jin Lecture 14 Phase Rule
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2010 © X. J. Jin Lecture 14 Phase Rule Page 8/45 8.4 Equilibrium Conditions Equilibrium conditions: The chemical potential (partial molar Gibbs free energy) of a component must be the same throughout the system. Intensive properties REL C(P1) p i i i i i ... 1 2 3 4 p i the chemical potential of component i in phase p The total number of relationship
8.5 Gibbs Phase Rule S.J.T.U. Phase Transformation and Applications Page 9/45 Degrees of freedom available in the system(F): VAR:the number of variables required to specify the system REL:the number of relationships required by the equilibrium condition F-VAR-REL F=P(C-1)+2-C(P-1) F=C-P+2 F:the number of system variables that we may freely vary,or arbitrarily fix n C:components P:phase SJTU Thermodynamics of Materials Spring2010©X.J.Jin Lecture 14 Phase Rule
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2010 © X. J. Jin Lecture 14 Phase Rule Page 9/45 8.5 Gibbs Phase Rule Degrees of freedom available in the system (F): VAR: the number of variables required to specify the system REL: the number of relationships required by the equilibrium condition F VAR REL F: the number of system variables that we may freely vary, or arbitrarily fix C: components P: phase F P(C 1) 2C(P1) F C P 2 n
8.6 One-component System S.J.T.U. Phase Transformation and Applications Page 10/45 Degrees of freedom available in the system(F): F=C-P+2 F:the number of system variables that we may freely vary,or arbitrarily fix C:components P:phase C=1 P=1,F=2 Minimum of P and F:1.0 P=2,F=1 fusion、 critical vaporization point P=3,F=0 (solid) (liquid) Phase diagram sublimation triple point (vapour) Maximum of F:2 temperature- SJTU Thermodynamics of Materials Spring2010©X.J.Jin Lecture 14 Phase Rule
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2010 © X. J. Jin Lecture 14 Phase Rule Page 10/45 8.6 One-component System Degrees of freedom available in the system (F): F: the number of system variables that we may freely vary, or arbitrarily fix C: components P: phase F C P 2 C 1 3, 0 2, 1 1, 2 P F P F P F Phase diagram Minimum of P and F: 1,0 Maximum of F: 2