材料科学基础-第7章2合金相图_ppt课件

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1、1二元共晶相图Pb-Sb、Pb-Sn、Ag-Cu、Al-Si、Zn-Sn等合金相图都属于共晶相图，在Mg-Al及Fe-Fe3C相图中也包含有共晶部分。共晶反应；共晶组织（共晶体）Section7.4二元共晶相图及其合金的结晶图7-13Pb-Sn二元相图2点、线、区分析、固溶体；最大溶解度；室温下溶解度；熔点，共晶点三相共存水平线（区）边际（端部）固溶体合金；共晶合金；亚共晶合金；过共晶合金相律应用7.4.1二元共晶相图分析图7-13Pb-Sn二元相图3Solvus-Asolubilitycurvethatseparatesasingle-s

2、olidphaseregionfromatwo-solidphaseregioninthephasediagram.Isopleth-Alineonaphasediagramthatshowsconstantchemicalcomposition.Hypoeutecticalloy-Analloycompositionbetweenthatoftheleft-hand-sideendofthetielinedefiningtheeutecticreactionandtheeutecticcomposition.Hypereutecticallo

3、ys-Analloycompositionbetweenthatoftheright-hand-sideendofthetielinedefiningtheeutecticreactionandtheeutecticcomposition.TheEutecticPhaseDiagram4边际（端部）固溶体，二次结晶→Ⅱ共晶合金亚共晶合金过共晶合金7.4.2典型合金的平衡结晶过程及室温平衡组织5Figurethelead-tinequilibriumphasediagram.8Determine(a)thesolubilityoftinins

4、olidleadat100oC,(b)themaximumsolubilityofleadinsolidtin,(c)theamountofβthatformsifaPb-10%Snalloyiscooledto0oC,(d)themassesoftincontainedintheαandβphases,and(e)massofleadcontainedintheαandβphases.AssumethatthetotalmassofthePb-10%Snalloyis100grams.ExamplePhasesintheLead–Tin(Pb

5、-Sn)PhaseDiagram9FigureSolidification,precipitation,andmicrostructureofaPb-10%Snalloy.Somedispersionstrengtheningoccursastheβsolidprecipitates.10ExampleSOLUTION(a)The100oCtemperatureintersectsthesolvuscurveat5%Sn.Thesolubilityoftin(Sn)inlead(Pb)at100oCthereforeis5%.(b)Themax

6、imumsolubilityoflead(Pb)intin(Sn),whichisfoundfromthetin-richsideofthephasediagram,occursattheeutectictemperatureof183oCandis97.5%Sn.(c)At0oC,the10%Snalloyisinaα+βregionofthephasediagram.Bydrawingatielineat0oCandapplyingtheleverrule,wefindthat:11ExampleSOLUTION(Continued)(d)

7、ThemassofSnintheαphase=2%Sn91.8gofαphase=0.0291.8g=1.836g.Sincetin(Sn)appearsinboththeαandβphases,themassofSnintheβphasewillbe=(10–1.836)g=8.164g.(e)MassofPbintheαphase=98%Sn91.8gofαphase=0.9891.8g=89.964gMassofPbintheβphase=90-89.964=0.036g.12FigureSummaryofcalculations

8、13FigureSolidificationandmicrostructureoftheeutecticalloyPb-61.9%Sn.14Figur