3－物理冶金原理－合金相图与凝固(1)

null1、液态金属的结构： 金属熔化时物理性质的变化  体积膨胀约3～5%、配位数约11、原子间距增加约1～1.5%: 原子间结合力仍很强！ 熔化潜热约为蒸发热的3～7％：原子间结合力仍很强； 液态金属的结构更接近固体1、液态金属的结构： 金属熔化时物理性质的变化  体积膨胀约3～5%、配位数约11、原子间距增加约1～1.5%: 原子间结合力仍很强！ 熔化潜热约为蒸发热的3～7％：原子间结合力仍很强； 液态金属的结构更接近固体一、Structure of Liquid Metals Short-Range Order 近程有序 Structure Fluctuation 结构起伏 Composition Fluctuation 成分起伏一、Structure of Liquid Metals Short-Range Order 近程有序 Structure Fluctuation 结构起伏 Composition Fluctuation 成分起伏2、Properties of Liquid Metals Fluidity 流动性 Viscosity 粘度 Surface Tension 表 关于同志近三年现实表现材料材料类招标技术评分表图表与交易pdf视力表打印pdf用图表说话 pdf 面张力 Diffusion Coefficient 扩散系数 Electric Resistance 电阻2、Properties of Liquid Metals Fluidity 流动性 Viscosity 粘度 Surface Tension 表面张力 Diffusion Coefficient 扩散系数 Electric Resistance 电阻Structure of Amorphous Alloys Short-Range Order No Grain Boundaries No Dislocations Chemical HomogeneityStructure of Amorphous Alloys Short-Range Order No Grain Boundaries No Dislocations Chemical HomogeneityThe atoms are arranged in a random fashion, similar to their arrangement in the liquid state Example of a crystalline atomic structure.  Four grains are illustrated金属的凝固 Solidification of Metals 形核与长大 Nucleation and Growth金属的凝固 Solidification of Metals 形核与长大 Nucleation and Growth形核 Nucleation形核 Nucleation形核的热力学条件:过冷 “过冷” Undercooling “过冷度” Degree of Undercooling nullG = H – TS DGv = Gs – GL = Hs-HL - T(Ss-SL) = DH-T.DS DSm = DH/Tm DGv = (DHm/Tm).DTSpontaneous Nucleation 自发形核（均匀形核）Spontaneous Nucleation 自发形核（均匀形核）Spontaneous Nucleation 自发形核（均匀形核）Spontaneous Nucleation 自发形核（均匀形核）Spontaneous Nucleation 自发形核（均匀形核）Spontaneous Nucleation 自发形核（均匀形核）r临界形核功： Critical Energy of Nucleation临界形核功： Critical Energy of Nucleation形核率及其主要影响因素形核率及其主要影响因素过冷度的影响Nr*rDT*DTTm (DT=0)形核率及其主要影响因素形核率及其主要影响因素原子扩散能力的影响NDTDTTm (DT=0)nullHeterogeneous NucleationHeterogeneous NucleationDG= -gML .S1 + gMS.S1 + gSL.S2 S1=f1(q); S2=f2(q) rc=2ssL/DGv DG*= DGC.f1(q)Effect of Wetting AngleEffect of Wetting Angleq=0: Complete Wetting No nucleation is needed q=180: No wettingSpontaneous Nucleation晶体生长－Crystal Growth晶体生长－Crystal Growth热力学条件:过冷Undercooling 生长机制: 液-固界面结构与Jackson因子纯金属凝固典型冷却曲线 Typical Cooling Curve of a Pure Metal纯金属凝固典型冷却曲线 Typical Cooling Curve of a Pure MetalDTkDT＊TmTimeTemperatureAtomically Rough S/L Interface （原子尺度）粗糙液－固界面Atomically Rough S/L Interface （原子尺度）粗糙液－固界面Continuous Growth --连续生长 Non-faceted Phases (非小面相）连续生长－Continuous Growth （Non-Faceted Crystal）连续生长－Continuous Growth （Non-Faceted Crystal）所需界面动力学过冷度很小 生长速度与过冷度呈线性关系 晶体外形圆滑、无棱角Non-faceted PhasesNon-faceted PhasesnullnullEffect of Solidification Cooling Rate on DASEffect of Solidification Cooling Rate on DASEffect of SDAS on Tensile StrengthEffect of SDAS on Tensile StrengthAtomically Smooth S/L Interface （原子尺度）光滑液固界面Atomically Smooth S/L Interface （原子尺度）光滑液固界面Lateral Growth– 侧向生长 Faceted Phase—小面相台阶侧向生长: lateral or edgewise growth台阶侧向生长: lateral or edgewise growth表面二维形核侧向生长 Lateral Growth by Steps due to Surface Two-Dimensional Nucleation表面二维形核侧向生长 Lateral Growth by Steps due to Surface Two-Dimensional Nucleation密排面－－低界面能null所需动力学过冷度很大 生长速度与过冷度呈指数关系 晶体生长表面棱角分明(Faceted Crystal)Lateral Growth by Steps from a Screw DislocationLateral Growth by Steps from a Screw Dislocationnull所需动力学过冷度较大 生长速度与过冷度呈对数关系 晶体生长表面棱角分明(Faceted Crystal) 能观察到螺旋状生长台阶气相沉积生长SiC晶体表面螺旋生长台阶气相沉积生长SiC晶体表面螺旋生长台阶晶体生长的台阶机制 晶体中确实存在螺位错Growth Steps on a Rapidly Solidified TiC Crystal SurfaceGrowth Steps on a Rapidly Solidified TiC Crystal SurfacenullFaceted Phases Ti5Si3Faceted Phases Ti5Si3nullNon-Faceted and Faceted PhasesNon-Faceted and Faceted Phases正温度梯度：平界面稳定正温度梯度：平界面稳定Solid S/L Interface Liquid定向凝固 Directional Solidificationnull负温度梯度：平界面失稳负温度梯度：平界面失稳Solid S/L Interface Liquid晶体生长过程中平界面的稳定性Planar S/L Interface Stability晶体生长过程中平界面的稳定性Planar S/L Interface StabilityFe-Dendrite in Cu Matrix in Fe-20vol%Cu alloy Fe-20vol%Cu合金中Fe树枝晶SEM照片Fe-Dendrite in Cu Matrix in Fe-20vol%Cu alloy Fe-20vol%Cu合金中Fe树枝晶SEM照片Effect of Solidification Cooling Rate on DASEffect of Solidification Cooling Rate on DASEffect of SDAS on Tensile StrengthEffect of SDAS on Tensile Strength自由生长树枝晶自由生长树枝晶S/L界面处负的温度梯度 “平界面”失稳形成自由生长等轴树枝晶 Free-Grown Equiaxed Dendritenull自由生长树枝晶自由生长树枝晶S/L界面处负的温度梯度 “平界面”失稳形成自由生长等轴树枝晶 Free-Grown Equiaxed DendritePreferred Orientation of Crystal Growth 晶体生长过程中的择优取向性Preferred Orientation of Crystal Growth 晶体生长过程中的择优取向性e.g.立方系金属择优生长方向: <100>晶向Fe-Dendrite in Cu Matrix in Fe-20vol%Cu alloy Fe-20vol%Cu合金中Fe树枝晶SEM照片Fe-Dendrite in Cu Matrix in Fe-20vol%Cu alloy Fe-20vol%Cu合金中Fe树枝晶SEM照片Preferred Orientation and Competitive Growth of Crystal Growth Preferred Orientation and Competitive Growth of Crystal Growth Competitive Growth Induced Natural Selection of Columnar Grains (Struggle for existence, the Fittest Survives!)Competitive Growth Induced Natural Selection of Columnar Grains (Struggle for existence, the Fittest Survives!)null择优取向与竞争生长择优取向与竞争生长控制凝固过程细化晶粒的方法控制凝固过程细化晶粒的方法加大冷却速度提高过冷度（降低浇铸温度、提高铸型冷却能力、减小零件壁厚、强制冷却、内外“冷铁”，等等） 熔体纯净化(深过冷)提高过冷度 加强液态金属的流动（浇铸方式、机械搅拌与振动、电磁及超声搅拌与振动等等） 型壁晶体的游离 枝晶臂断裂与游离 孕育处理 微合金化处理nullSeparation of Crystal from Mould Wall due to Convection nullSeparation of Crystal from Mould Wall due to Convection nullSeparation of Crystal from Mould Wall due to Convection nullnullSeparation of Crystal from Mould Wall due to Convection nullBreaking of Dendrite-Arms due to Melt Convection nullnull典型金属铸锭组织及形成机理 表面细小等轴晶区 柱状晶区 内部粗大等轴晶区 中心缩孔、气孔、夹杂物、低熔点杂质、null金属的熔化与过热: Surface Nucleation  No Superheating NeededsSG > sSL + sLG二元合金相图与二元合金的凝固 Binary Phase Diagrams and Solidification of Binary Alloys二元合金相图与二元合金的凝固 Binary Phase Diagrams and Solidification of Binary Alloys相图及其建立方法相图及其建立方法相图 相图的建立方法 相律 相图的建立方法相图的建立方法实验方法：临界点的测定 热力学计算： 冷却曲线－Cooling Curve冷却曲线－Cooling CurveAB热力学计算法: 化学位热力学计算法: 化学位GABAmAmBGBmA = RT ln aA mB = RT ln aB cA相平衡条件相平衡条件元素在平衡相中的化学位相等 热力学计算法热力学计算法abGBAmAmBnull相平衡规律：相律相平衡规律：相律体系自由度 f＝n – p + 2 f＝n – p + 1（常压条件）常见基本相图类型常见基本相图类型1、匀晶相图（无限互溶单相固溶体）Isomorphous Solidus LineLiquidus Linea+LLa(f=2-1+1=2)(f=2-1+1=2)(f=2-2+1=1)2、共晶相图：Eutectic Phase Diagram LE  (a+b) 三相平衡 f=2-3+1=02、共晶相图：Eutectic Phase Diagram LE  (a+b) 三相平衡 f=2-3+1=0nullnullnullnull单相二元合金的凝固 Solidification of Single-Phase Binary Alloys单相二元合金的凝固 Solidification of Single-Phase Binary Alloys一、相图分析： 液相线－Liquidus; 固相线－Solidus; 液相区; 固相区; 两相区. 自由度null二、单相合金的平衡凝固：Equilibrium Solidification 1. 合金凝固过程中溶质再分配现象： Solute Redistribution during Solidification 溶质再分配系数： k = Cs/CL Solute Redistribution (Partition) Coefficient Cs＝ k CLnullWaWLCoCLCaTsTLnull二、单相合金的平衡凝固：Equilibrium Solidification 2. 两相平衡的基本规则：杠杆规则 Lever Rule 平衡相之成分点：连接线－tie-line or Conode 平衡相之相对重量百分数：杠杆定律Lever Rule WS × (Co－Cs) = WL × (CL－Co) WS WLCs Co CL平衡凝固过程及冷却曲线平衡凝固过程及冷却曲线null3、合金平衡凝固过程分析TSTLCokConull平衡凝固过程null三、单相合金的非平衡凝固及凝固偏析规律： 基本假设： 1)、液固界面处两相局域平衡： Local equilibrium at S/L interface Cs/CL=k 2)、液相线及固相线均为直线：k=constant 3)、液-固界面保持平面：Planar S/L interfacenull固相无扩散、液相完全混合 No Diffusion in Solid and Complete Mixing in Liquid固相无扩散、液相完全混合 No Diffusion in Solid and Complete Mixing in LiquiddfS×(CL-CS)= (1-fS)×dCL Boundary Condition: When fS=0, CS=kOCO CS=kCO(1-fS)ko-1 CL=CO(1-fS)ko-1fs1液相完全混合条件下定向生长晶体中溶质分布规律 液相完全混合条件下定向生长晶体中溶质分布规律 Scheil Equation：非平衡凝固杠杆规则 CS=kCO(1-fS)ko-1 CL=CO(1-fS)ko-1固相无扩散、液相完全混合 No Diffusion in Solid and Complete Mixing in Liquid固相无扩散、液相完全混合 No Diffusion in Solid and Complete Mixing in LiquidkCO CO CL=CO/k CETL T1 TSDendritic Segregation and Interdendritic SegregationDendritic Segregation and Interdendritic SegregationSegregation-Induced Interdendritic EutecticsPrimary DendriteNonequilibrium Eutectic in Co3Mo2Si Metal Silicide AlloyNonequilibrium Eutectic in Co3Mo2Si Metal Silicide AlloyCo3Mo2SiCoNonequilibrium Eutectic in Co3Mo2Si Metal Silicide AlloyNonequilibrium Eutectic in Co3Mo2Si Metal Silicide AlloyCo3Mo2Si Co3Mo2SiSolidification Segregation 凝固偏析的分类： 晶内偏析（枝晶偏析） 晶界偏析 宏观偏析 微观偏析 减轻或消除凝固偏析的方法： 平衡凝固：无偏析 细化晶粒 快速凝固 均匀化退火消除 Solidification Segregation 凝固偏析的分类： 晶内偏析（枝晶偏析） 晶界偏析 宏观偏析 微观偏析 减轻或消除凝固偏析的方法： 平衡凝固：无偏析 细化晶粒 快速凝固 均匀化退火消除 凝固偏析的危害 化学成分不均匀：性能不均匀、降低性能 合金元素作用得不到发挥： 形成有害相、降低合金使用性能 降低合金初熔温度和使用温度 降低合金工艺性能或无法进行二次加工处理 凝固偏析的危害 化学成分不均匀：性能不均匀、降低性能 合金元素作用得不到发挥： 形成有害相、降低合金使用性能 降低合金初熔温度和使用温度 降低合金工艺性能或无法进行二次加工处理 凝固偏析的应用危害 金属的提纯： 低熔点液相－－补缩 形成晶界强化相 形成自润滑相、耐磨相等凝固偏析的应用危害 金属的提纯： 低熔点液相－－补缩 形成晶界强化相 形成自润滑相、耐磨相等Zone Melting/Refining of Metals 金属的区域熔化提纯：非平衡凝固偏析现象的应用 Zone Melting/Refining of Metals 金属的区域熔化提纯：非平衡凝固偏析现象的应用 Scheil Equation：CS=kCO(1-fS)ko-1固相无扩散、液相无对流 No Diffusion in Solid, Diffusional Mixing in Liquid固相无扩散、液相无对流 No Diffusion in Solid, Diffusional Mixing in Liquid熔体中无对流条件下定向凝固晶体中溶质偏析规律 Solute Distribution for an Unidirectionally Solidified Crystal without Convection in Melt 熔体中无对流条件下定向凝固晶体中溶质偏析规律 Solute Distribution for an Unidirectionally Solidified Crystal without Convection in Melt null组成过冷-Constitutional Supercooling组成过冷-Constitutional SupercoolingFormation of a Solute-Enriched Boundary Layer in front of the S/L interface Real Liquidus Temperature Real Undercooling Distrbution in the Solute-Enriched Layer Constitutional Supercooling and Solidification Interface Morphology 组成过冷及凝固界面形态Constitutional Supercooling and Solidification Interface Morphology 组成过冷及凝固界面形态组成过冷的产生 质量守恒： R(CL-Co) = -D(dCL/dx) 边界条件： X=0, CL=Co/k X=infinite, CL=Co 溶质边界层中溶质浓度分布 CL=Co{1-[(1-k)/k ] exp(-Rx/D)}nullTo-TL = m (CL-Co )  TL=To-m (CL-Co ) 或Tm-TL = mCL  TL=Tm-m CL 溶质边界层中熔体的实际液相线温度 TL =Tm- m Co{1-[(1-k)/k ] exp(-Rx/D)}CL nullTsT0C0C0／kTLCLTm-TL = m CL TL=Tm-mCL ＝ Tm- m Co{1-[(1-k)/k ] exp(-Rx/D)}nullC0C0／kTLCLTm-TL = m CL TL=Tm-mCL ＝ Tm- m Co{1-[(1-k)/k ] exp(-Rx/D)}null组成过冷 DT = TL – GLX = Tm- m Co{1-[(1-k)/k ] exp(-Rx/D)} – GLX DTmax = XC = TLGLXCDTmaxnullPlanar-Front SolidificationPlanar-Front SolidificationNo constitutional supercoolingCellular Front Solidification Mushy Zone Cellular Front Solidification Mushy Zone Mushy ZoneCellular Structure of DS Ni-Base Single-Crystal SuperalloyCellular Structure of DS Ni-Base Single-Crystal SuperalloyPulsed Laser Melted/Rapidly Solidified Cellular Structure of Ni-Base Superalloy 脉冲激光重熔／快速凝固镍基高温合金胞状晶Pulsed Laser Melted/Rapidly Solidified Cellular Structure of Ni-Base Superalloy 脉冲激光重熔／快速凝固镍基高温合金胞状晶nullDendritic Front Solidification with Large Constitutional SupercoolingDendritic Front Solidification with Large Constitutional SupercoolingnullnullnullnullMushy ZoneToTL Ts Critical Effect of Temperature Gradient on Mushy Zone, DAS, Segregation, Interdendritic Pores and EutecticsCritical Effect of Temperature Gradient on Mushy Zone, DAS, Segregation, Interdendritic Pores and EutecticsLower G  Longer Dmushy zone  Larger DAS  Severer Segregation Lower G  Larger Dmushy zone  Larger DAS  Larger and more Interdendritic Pores Lower G  Larger Dmushy zone  Stronger Interdendritic Fluid Flotation  More Dendrite Arm Breaking  More Prone to FreckelsliquidussolidusCritical Effect of Temperature Gradient on Mushy Zone, DAS, Segregation, Interdendritic Pores and EutecticsCritical Effect of Temperature Gradient on Mushy Zone, DAS, Segregation, Interdendritic Pores and EutecticsLower G  Longer Dmushy zone  Larger DAS  Severer Segregation Lower G  Larger Dmushy zone  Larger DAS  Larger and more Interdendritic Pores Lower G  Larger Dmushy zone  Stronger Interdendritic Fluid Flotation  More Dendrite Arm Breaking  More Prone to Freckelsnull[010][001][100]Formation of Pores or Shrinkage Cavity in the Interdendricitic ZoneFormation of Pores or Shrinkage Cavity in the Interdendricitic ZoneEffect of Solidification Cooling Rate on DASEffect of Solidification Cooling Rate on DASEffect of SDAS on Tensile StrengthEffect of SDAS on Tensile StrengthBinary Eutectic Phase Diagrams and Solidification of Binary Eutectic Alloys 二元共晶合金相图及二元共晶合金的凝固Binary Eutectic Phase Diagrams and Solidification of Binary Eutectic Alloys 二元共晶合金相图及二元共晶合金的凝固 f = 0, LE = (aA + bB) 共晶反应或共晶凝固Eutectic Reaction or Eutectic Solidification 共晶组织 Eutectics or Eutectic Structure f = 0, LE = (aA + bB) 共晶反应或共晶凝固Eutectic Reaction or Eutectic Solidification 共晶组织 Eutectics or Eutectic StructureLEL + aL+ba + bbaBATETEnullnullEutectic Growth: Coupled GrowthnullEutectic Growth: Coupled GrowthnullCr/Cr3Si共晶团- Eutectic Colonies共晶转变 L  (Cr3Si + Cr) 相图分析：液相线、固相线、共晶线、固溶度曲线 共晶线： f = 0, LE = (aA + bB) 固溶度曲线：溶质在固溶体中固溶度随温度的变化曲线 相图分析：液相线、固相线、共晶线、固溶度曲线 共晶线： f = 0, LE = (aA + bB) 固溶度曲线：溶质在固溶体中固溶度随温度的变化曲线 LEL + aL+ba + bbaBATE共晶凝固的特点共晶凝固的特点三相平衡f=0，在恒温条件下进行 合金系中熔点最低：合金熔炼与铸造容易 结晶温度间隔为零、糊状区很小或无糊状区：难产生凝固偏析、难产生凝固缩孔与疏松 定向凝固可获得自生复合材料（Unidirectionally Solidified in-situ Composites） 铸造性能优异： 流动性及补缩性能很好：可浇注很薄的铸件、不易产生缩孔等缺陷 铸件不易产生凝固开裂现象（热裂Hot Tearing、冷裂Cold Cracking)共晶凝固过程动力学共晶凝固过程动力学一、协同形核 Cooperative Nucleation 一相自液相中领先析出 界面前沿溶质富集促进另一相协同析出 通过搭桥（Bridging）、分枝（Branching or Bifurcating）等协同方式侧向扩展（Edgewise Advancement）；null二、协同生长 Cooperative or Coupled Growth 相互促进nullEutectic LiquidbaaabbbCoupled or Cooperative Growth of a Eutectic by Edgewise Solute Diffusion at the Solidification InterfaceCooperative or Coupled Growth Cooperative or Coupled Growth 共晶组织分类：Classification of Eutectics共晶组织分类：Classification of Eutectics一、按共晶组织形态分类：Morphological Classification 层片状共晶－Lamellar Eutectic 杆状共晶 －Rod-like Eutectic 点状共晶－Dod-like Eutectic 不规则共晶－Irregular Eutectic 离异共晶－Divorced Eutectic共晶组织分类：Classification of Eutectics共晶组织分类：Classification of Eutectics二、按共晶组成相的性质： Non-Faceted/Non-Faceted共晶 Non-Faceted/Faceted共晶 Faceted/Faceted共晶 DS Lamellar Cr3Si/Cr Eutectic 定向凝固Cr3Si/Cr层片状共晶Lamellar Spacing 片层间距 l2R=knullLamellar Fe3C/Fe Eutectic Fe3C/Fe层片状共晶(莱氏体)null②Mo2Ni3Si/g 共晶团Mo2Ni3Si/g Eutectic ColoniesnullCr/Cr3Si共晶团- Eutectic Colonies共晶转变 L  (Cr3Si + Cr) nullDS Rod-like g/g’-Mo Eutectic 定向凝固杆状g/g’-Mo共晶nullMo-g/g’ “in-situ” Eutectic CompositeDS Rod-like g/g’-Mo Eutectic 定向凝固杆状g/g’-Mo共晶DS Rod-Like Cr3Si/Cr EutecticDS Rod-Like Cr3Si/Cr EutecticDot-Like EutecticDot-Like EutecticnullLaser Melted Rapidly Solidified Irregular Fe3C/Fe Eutectic 不规则共晶nullLaser Melted Rapidly Solidified Irregular Fe3C/Fe Eutectic 不规则共晶nullIrregular Mo2Ni3Si/Ni Eutectic Mo2Ni3Si/Ni不规则共晶nullIrregular Mo2Ni3Si/Ni Eutectic Mo2Ni3Si/Ni不规则共晶null完全无共晶组织特征的共晶组织 －球墨铸铁组织：Ductile Cast IronnullSynthesis of Novel Iron-Base Material Containing Ultra-fine nodular Graphite Particles by Pulsed Nd:YAG Laser Annealing of Laser Melted/Rapidly Solidified Cast Ironnull 非共晶成分合金(亚共晶、过共晶)的凝固 Solidification of Off-Eutectic （Hypoeutectic or Hyper-eutectic) Alloys 非共晶成分合金(亚共晶、过共晶)的凝固 Solidification of Off-Eutectic （Hypoeutectic or Hyper-eutectic) Alloysa+La+L两相平衡： 杠杆规则！ 计算共晶转变开始时、 共晶转变完成时及室温 组织中相组成及组织组 组成的相对重量百分数！Liquida + b ba A B Raa/b eutecticTimeTemperaturenull晶体生长过程中平界面的稳定性Planar S/L Interface Stability晶体生长过程中平界面的稳定性Planar S/L Interface Stabilitynull杆杆规则：两相平衡 gE%=oC/EC LE%=Ledeburite%=oE/ECnullCr3SiCr3Si/Crnullnull①null③null④nullnullBlocky Primary Ti5Si3 + Ti5Si3/Ti EutecticAl－Si合金相图Al－Si合金相图Al-Si合金共晶组织的变质处理 Modification Al-Si Eutectic StructureAl-Si合金共晶组织的变质处理 Modification Al-Si Eutectic StructurenullGrain Refining of Primary Silicon in Al-Si Cast Alloys by Phospherous Addition非平衡凝固共晶组织 Segregation Induced Eutectic Structure under Nonequilibriem Solidification Conditions非平衡凝固共晶组织 Segregation Induced Eutectic Structure under Nonequilibriem Solidification Conditions晶体生长过程中平界面的稳定性Planar S/L Interface Stability晶体生长过程中平界面的稳定性Planar S/L Interface Stability共生区与伪共晶： Coupled Zone and Pseudo-Eutectic 共生区与伪共晶： Coupled Zone and Pseudo-Eutectic LEL + aL+ba + bbaBATENon-equilibrium Eutectic (Divorced Eutectic ) in Co3Mo2Si Metal Silicide AlloyNon-equilibrium Eutectic (Divorced Eutectic ) in Co3Mo2Si Metal Silicide AlloyCo3Mo2SiCoNon-equilibrium Eutectic (Divorced Eutectic ) in Co3Mo2Si Metal Silicide AlloyNon-equilibrium Eutectic (Divorced Eutectic ) in Co3Mo2Si Metal Silicide AlloyCo3Mo2Si Co3Mo2SinullDivorced EutecticnullDivorced Eutecticnull完全离异形核、离异生长的共晶组织 －球墨铸铁组织：Ductile Cast IronnullCritical Solidification Processing Conditions for Directionally Aligned Eutectic CompositesCritical Solidification Processing Conditions for Directionally Aligned Eutectic CompositesHigh GL and Slow R to Guarantee Planar Solid-Liquid Interface! Cellular S/L Interface Planar S/L InterfaceLiquidDirectionally Solidified in-situ Fibrous g/Cr7C3 High-Temperature Wear Resistant CompositeDirectionally Solidified in-situ Fibrous g/Cr7C3 High-Temperature Wear Resistant Compositeg/Cr7C3Primary CarbideBinary Peritectic Phase Diagrams and Solidification of Binary Peritectic Alloys 二元胞晶合金相图及二元胞晶合金的凝固Binary Peritectic Phase Diagrams and Solidification of Binary Peritectic Alloys 二元胞晶合金相图及二元胞晶合金的凝固nullnullL66.3 + a10.5  b42.4 需要原子固态长程扩散与晶体结构转变nullL66.3 + a10.5  b42.4 原子固态长程扩散 晶体结构转变 转变速度慢、转变通常难以完成！a10.5胞晶转变开始前： Lc＝PD/PC b＝DC/PC 胞晶转变完成后： a＝100％ 室温：nullL66.3 + a10.5  b42.4 需要原子固态长程扩散与晶体结构转变胞晶转变前： LC% = PD/PC aP% = DC/PC 室温时的相及组织组成： bF% = EK/EF (aII )E % = KF/EF Knull用杆杆规则计算：胞晶转变前、胞晶转变完成后、室温：相组成及组织组成重量百分比。null胞晶转变前： LC% = PH/PC aP% = HC/PC 胞晶转变完成时： aP% = HD/PD bD% = PH/PD 室温时相组成： aE% = KF/EF bF% = EK/EF 室温时组织组成： bII% = aE%.(EPo/EF) aII% = bF%.EK/EF a% = aP% - bII% b% = bD% - aII%KPoDo杆杆规则：两相平衡！null包晶转变 L + NiTi  NiTi2 B2 cF96包晶转变 L + NiTi  NiTi2 B2 cF96NiTiNiTi2Ti NinullCr3SiL36 + (Cr5Si3)27  (CrSi)35Cr5Si3Cr5Si3CrSiSi Cr 原子固态扩散 晶体结构的重构 转变速度很慢，通常难以完成