Chapter 11: Phase Diagrams - CHERIC

1 Chapter 11 -AMSE 205 Spring 20161 ISSUES TO When we combine two is the resulting equilibrium state? In particular, if we the composition ( , wt% Cu - wt% Ni), and-- the temperature (T) many phases form?What is the composition of each Phase ?What is the amount of each Phase ? Chapter 11: Phase DiagramsPhase BPhase ANickel atomCopper atomChapter 11 -AMSE 205 Spring 20162 Phase Equilibria: Solubility LimitQuestion:What is thesolubility limit for sugar in water at 20 oC ?Answer: 65 wt% 20 C, if C< 65 wt% sugar:syrupAt 20 C, if C> 65 wt% sugar:syrup + sugar65 Solubility Limit:Maximum concentration forwhich only a single Phase solution Phase DiagramSugarTemperature (oC)02040 6080 100C= Composition (wt% sugar)L(liquid solution , syrup)Solubility LimitL(liquid) + S(solid sugar)20406080100 WaterAdapted from Fig.

2 , Callister & Rethwisch 9e. Solution solid, liquid, or gas solutions, single Phase Mixture more than one phaseChapter 11 -AMSE 205 Spring 20163 Components:The elements or compounds which are present in the alloy( , Al and Cu) phases :The physically and chemically distinct material regionsthat form ( , and ).Aluminum-CopperAlloyComponents and phases (darker Phase ) (lighter Phase )Adapted from Chapter -opening photograph, Chapter 9, Callister, Materials Science & Engineering: An Introduction, 3e. Chapter 11 -AMSE 205 Spring 2016470 80 1006040200 Temperature (oC)C= Composition (wt% sugar)L(liquid solution , syrup)201004060800L(liquid) + S(solid sugar)Effect of Temperature & Composition Altering Tcan change # of phases : path Ato B. Altering Ccan change # of phases :path Bto , Callister & Rethwisch (100 oC, C= 90)2 phases B(100 oC, C= 70)1 Phase A(20 oC, C= 70)2 phasesChapter 11 -AMSE 205 Spring 20165 Criteria for Solid Solubility CrystalStructureelectronegr(nm) Both have the same crystal structure (FCC) and have similar electronegativities and atomic radii (W.)

3 Hume Rothery rules) suggesting high mutual solubility. Simple system( , Ni-Cu solution) Ni and Cu are totally soluble in one another for all 11 -AMSE 205 Spring 20166 Phase Diagrams Indicate phases as a function of T, C, and P. For this course:- binary systems: just 2 independent variables: Tand C(P= 1 atm is almost always used).PhaseDiagramfor Cu-NisystemFig. (a), Callister & Rethwisch 9e.(Adapted from Phase Diagrams of BinaryNickel Alloys, P. Nash, Editor, 1991. Reprintedby permission of ASM International, MaterialsPark, OH.) 2 phases :L(liquid) (FCC solid solution) 3 different Phase fields: LL+ wt% Ni20 40 60 80 10001000110012001300140015001600T(oC)L(l iquid) (FCC solid solution) Chapter 11 -AMSE 205 Spring 20167Cu-NiphasediagramIsomorphous Binary Phase Diagram Phase diagram:Cu-Ni system.

4 System is:Fig. (a), Callister & Rethwisch 9e.(Adapted from Phase Diagrams of BinaryNickel Alloys, P. Nash, Editor, 1991. Reprintedby permission of ASM International, MaterialsPark, OH.) , 2 components:Cu and , completesolubility of onecomponent inanother; phasefield extends from0 to 100 wt% Ni20 40 60 80 10001000110012001300140015001600T(oC)L(l iquid) (FCC solid solution) Chapter 11 -AMSE 205 Spring 2016wt% Ni20 40 60 80 10001000110012001300140015001600T(oC)L(l iquid) (FCC solidsolution)Cu-Niphasediagram8 Phase Diagrams :Determination of Phase (s) present Rule 1:If we know Tand Co, then we know:-- which Phase (s) is (are) present. Examples:A(1100 oC, 60 wt% Ni): 1 Phase : B(1250 oC, 35 wt% Ni): 2 phases : L+ B(1250 C,35)A(1100 C,60)Fig. (a), Callister & Rethwisch 9e.

5 (Adapted from Phase Diagrams of BinaryNickel Alloys, P. Nash, Editor, 1991. Reprintedby permission of ASM International, MaterialsPark, OH.) Chapter 11 -AMSE 205 Spring 20169wt% Ni2012001300T(oC)L(liquid) (solid)304050Cu-Ni systemPhase Diagrams :Determination of Phase compositions Rule 2:If we know Tand C0, then we can determine:-- the composition of each Phase . Examples:TAA35C032 CLAt TA= 1320 oC : Only Liquid (L) present CL= C0( = 35 wt% Ni)At TB= 1250 oC : Both and LpresentCL= Cliquidus( = 32 wt% Ni) C = Csolidus( = 43 wt% Ni)At TD= 1190 oC : Only Solid ( ) presentC = C0( = 35 wt% Ni)Consider C0= 35 wt% NiDTDtie line4C 3 Fig. (b), Callister & Rethwisch 9e.(Adapted from Phase Diagrams of BinaryNickel Alloys, P. Nash, Editor, 1991. Reprintedby permission of ASM International, MaterialsPark, OH.)

6 BTBC hapter 11 -AMSE 205 Spring 201610 Rule 3:If we know Tand C0, then can determine:-- the weight fraction of each Phase . Examples:At TA: Only Liquid (L) present WL= , W = 0At TD: Only Solid ( ) present WL= 0, W = Diagrams :Determination of Phase weight fractionswt% Ni2012001300T(oC)L(liquid) (solid)304050Cu-Ni systemTAA35C032 CLBTBDTDtie line4C 3 RSAt TB: Both and L = SR+SW RR+SConsider C0= 35 wt% NiFig. (b), Callister & Rethwisch 9e.(Adapted from Phase Diagrams of BinaryNickel Alloys, P. Nash, Editor, 1991. Reprintedby permission of ASM International, MaterialsPark, OH.) Chapter 11 -AMSE 205 Spring 201611 Tie line connects the phases in equilibrium with each other also sometimes called an isothermThe Lever RuleWhat fraction of each Phase ?Think of the tie line as a lever (teeter-totter)MLM RSwt% Ni2012001300T(oC)L(liquid) (solid)304050 BTBtie lineC0 CLC SRAdapted from Fig.

7 (b), Callister & Rethwisch 11 -AMSE 205 Spring 201612wt% Ni2012001300304050110 0L(liquid) (solid)T(oC)A35C0L: 35 wt%NiCu-Nisystem Phase diagram:Cu-Ni from Fig. , Callister & Rethwisch 9e. Consider microstuctural changes that accompany the cooling of aC0= 35 wt% Ni alloyEx: Cooling of a Cu-Ni Alloy46354332 : 43 wt% Ni L: 32 wt% NiB : 46 wt% NiL: 35 wt% NiCEL: 24 wt% Ni : 36 wt% Ni 2436D : 35 wt% Ni Chapter 11 -AMSE 205 Spring 201613 Mechanical Properties:Cu-Ni System Effect of solid solution strengthening on:-- Tensile strength (TS)-- Ductility (%EL)Adapted from Fig. (a), Callister & Rethwisch Strength (MPa)Composition, wt% NiCuNi0 20406080100200300400 TSfor pure NiTSfor pure CuElongation (%EL)Composition, wt% NiCuNi0204060801002030405060%ELfor pure Ni%ELfor pure CuAdapted from Fig.

8 (b), Callister & Rethwisch 11 -AMSE 205 Spring 2016142 componentshas a special compositionwith a min. melting , Callister & Rethwisch 9e [Adapted from Binary Alloy Phase Diagrams , 2nd edition, Vol. 1, T. B. Massalski (Editor-in-Chief), 1990. Reprinted by permission of ASM International, Materials Park, OH.].Binary-Eutectic Systems 3 single Phase regions (L, , ) Limited solubility: : mostly Cu : mostly Ag TE: No liquid below TE: Composition at temperature TE CEEx.: Cu-Ag systemCu-AgsystemL(liquid) L+ L+ C, wt% Ag20 40 6080 10002001200T(oC) Ccoolingheating Eutectic reactionL(CE) (C E) + (C E) Chapter 11 -AMSE 205 Spring 201615L+ L+ + 200T(oC) , wt% Sn2060 801000300100L(liquid) 183 For a 40 wt% Sn-60 wt% Pb alloy at 150 oC, determine:-- the phases presentPb-SnsystemEX 1: Pb-Sn Eutectic SystemAnswer: + -- the Phase compositions-- the relative amountof each phase15040C011C 99C SRAnswer:C = 11 wt% SnC = 99 wt% SnW =C -C0C -C =99 - 4099 - 11=5988= +S=W =C0-C C -C =RR+S=2988= - 1199 - 11 Answer:Fig.

9 , Callister & Rethwisch 9e.[Adapted from Binary Alloy Phase Diagrams , 2nd edition, Vol. 3, T. B. Massalski (Editor-in-Chief), 1990. Reprinted by permission of ASM International, Materials Park, OH.] Chapter 11 -AMSE 205 Spring 201616 Answer:C = 17 wt% Sn-- the Phase compositionsL+ + 200T (oC)C, wt% Sn2060 801000300100L(liquid) L+ 183 C For a 40 wt% Sn-60 wt% Pb alloy at 220 oC, determine:-- the phases present:Pb-SnsystemEX 2: Pb-Sn Eutectic System-- the relative amountof each phaseW =CL-C0CL-C =46 - 4046 - 17=629= CL-C =2329= 220 SRAnswer: + LCL= 46 wt% SnAnswer:Fig. , Callister & Rethwisch 9e.[Adapted from Binary Alloy Phase Diagrams , 2nd edition, Vol. 3, T. B. Massalski (Editor-in-Chief), 1990. Reprinted by permission of ASM International, Materials Park, OH.]

10 ] Chapter 11 -AMSE 205 Spring 201617 For alloys for which C0< 2 wt% Sn Result: at room temperature-- polycrystalline with grains of Phase having composition C0 Microstructural Developments in Eutectic Systems I0L+ 200T(oC)C, wt% Sn10220C0300100L 30 + 400(room Tsolubility limit)TE(Pb-SnSystem) LL: C0wt% Sn : C0wt% SnFig. , Callister & Rethwisch 11 -AMSE 205 Spring 201618 For alloys for which 2 wt% Sn < C0< wt% Sn Result: at temperatures in + range-- polycrystalline with grainsand small -phaseparticlesFig. , Callister & Rethwisch Developments in Eutectic Systems IIPb-SnsystemL+ 200T(oC)C, wt% 30 + 400(sol. limit at TE)TE2(sol. limit at Troom)L L: C0wt% Sn : C0wt% SnChapter 11 -AMSE 205 Spring 201619 For alloy of composition C0= CE Result:Eutectic microstructure (lamellar structure)-- alternating layers (lamellae) of and , Callister & Rethwisch Developments in Eutectic Systems IIIFig.