上游充通大粤 SHANGHAI JIAO TONG UNIVERSITY Chapter 9.Phase Diagram Ill Review: 是 Immiscibility:不溶性 Spinodal Points:拐点 Peritectic Phase diagram:包晶相图 Compounds:化合物 AIJIAO TONG UNIVE A Peng Zhang NoV25,2016
Chapter 9. Phase Diagram III Review: Immiscibility： 不溶性 Spinodal Points：拐点 Peritectic Phase diagram:包晶相图 Compounds：化合物 1 Peng Zhang Nov 25, 2016
上游充通大粤 SHANGHAI JIAO TONG UNIVERSITY Phase diagrams and Gibbs free energy diagram at certain Tempearture G G T a+8 A B 2
Phase diagrams and Gibbs free energy diagram at certain Tempearture 2
上游克通大学 SHANGHAI JIAO TONG UNIVERSITY 9.5 Immiscibility:Regular solution 4500 4000 m=17,D00md 3500 3000 2500 2000 1500 1000 白 500 025 0.5 0.75 出 ia) 0 -100 T=800K.w=17.000/m0 1t2 200 300 400 ®3025 0.5 0.758.4 1 -500 TON 想◆ -600 Figure 9.14 The miscibility gap in solid A-B solutions. 700 800 0.25 0.75 Figure 9.13 Plots of properties of mixing versus composition for regular solutions: (a)molar enthalpy and (b)molar Gibbs free energy. 3
9.5 Immiscibility: Regular solution 3
上游充通大粤 色 SHANGHAI JIAO TONG UNIVERSITY 9.6 Spinodal points 1050 1000 line 750 0 -100 600 T=800K,w=17,000 J/mol 0.25 0.5 0.75 -200 The decomposition here will cause the increase of Gibbs free energy Figure 9.15 The miscibility gap,showing spinodal line. 300 and therefore is relatively not favored 400 -500 △Gm decrease upon decomposition -600 -700 △Gm increase upon decomposition -800 0 xB.1 0.25 0.5 0.75 XB.2 xB→ 4
9.6 Spinodal points 4
上游充通大￥ SHANGHAI JIAO TONG UNIVERSITY 9.7 Peritectic phase diagrams Peritectic transformation A liquid phase and a solid phase can combine to form an entirely new solid phase Weight percent carbon 02 0.4 0.6 0.8 liquid+solid。=solid B 1538℃ L+6 0.741493 1 iquid+solid。=solid 1500 5Fe 2.43 0.40 onjeradwBl 6+y L+7 相律？ 1400 1394℃ YFe 1300 2 Fe Atomic percent carbon Figure 9.17 The binary phase diagram for carbon(graphite)and iron. 5
9.7 Peritectic phase diagrams 5
上游充通大粤 SHANGHAI JIAO TONG UNIVERSITY 9.8 Compounds 1600 1414 Mg:Si L 1200 L+Si 1087 946.7 赵 L+Mg 56.5 800 L+Mg2Si L+Mg:Si 649 638.8 MgSi+Si 1.38 Mg+Mg2Si 400 M 10 20 30 40 50 60 70 80 90 Si w(Si)/% 6
9.8 Compounds 6
1800A 上游充通大￥ 160U叶 SHANGHAI JIAO TONG UNIVERSITY 1400F 1200外 1186 66.3 10.5 B 1000 Points:A:Tm of Pt 800 B:Tm of Ag 600 P:Peritectic point。 400L The alloy at D is called peritectic alloy(包晶合金) (x)/% 2> Line:ACB:liquid phase line ADPB:solid phase line DE:solid solution curce of Ag in Pt PF:solid solution curce of Pt in Ag DPC:horizontal,called peritectic line. The alloys on this line is under peritectic reaction:Lc+pBp Regions:three single phase regione:L、ak、β solid solution of Ag in Pt β：solid solution of Pt in Ag three double phase regions:Ltau、L+β、a+B。 7
A Points：A：Tm of Pt B：Tm of Ag P：Peritectic point。 The alloy at D is called peritectic alloy(包晶合金) Line：ACB：liquid phase line ADPB：solid phase line DE：solid solution curce of Ag in Pt PF： solid solution curce of Pt in Ag DPC：horizontal, called peritectic line. The alloys on this line is under peritectic reaction: LC + αD →βP Regions： three single phase regione： L、α、β α：solid solution of Ag in Pt β：solid solution of Pt in Ag three double phase regions：L+α、L+β、α+β。 B 7
上游充通大粤 e SHANGHAI JIAO TONG UNIVERSITY Usage of phase diagrams 1 al with multi-components system -phase rule -Phase diagrams: 1.equilibrium phases under different conditions 2.What will happen to the phases while the Temp,pressure and/or composition changes 3.The conditions for phase transformation To investigate new materials Critical evidence to analyze the alloy components,chemical composition, and to design the manufacturing and thermal treatment process 8
Usage of phase diagrams 1 To deal with multi-components system -phase rule -Phase diagrams: 1.equilibrium phases under different conditions 2.What will happen to the phases while the Temp, pressure and/or composition changes 3.The conditions for phase transformation To investigate new materials Critical evidence to analyze the alloy components, chemical composition, and to design the manufacturing and thermal treatment process 8
上游充通大￥ SHANGHAI JIAO TONG UNIVERSITY Usage of phase diagrams 2 To purify a material in M 液相 certain region 固溶体 The impurities in the solid is less than in liquids 20B 熔 熔 图5-15区域熔炼示意图 9
Usage of phase diagrams 2 To purify a material in certain region The impurities in the solid is less than in liquids 9
上游充通大粤 SHANGHAI JIAO TONG UNIVERSITY Usage of phase diagrams 3 ·估算热力学数据，如 熔化热 一从相图上查出一定成 分的合金系统中，作 L(T-T) 为溶剂的金属熔点降 XB= 低了多少度，然后用 RTR 稀溶液凝固点下降的 依数性公式，即可估 算溶剂金属的摩尔熔 化焓 10
Usage of phase diagrams 3 10
