Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 1 Development of microstructure.

Slides:



Advertisements
Similar presentations
L10B: Phases in equilibrium with one another: Composition and amount of each The temperature and pressure must be the same in each phase in equilibrium.
Advertisements

Mechanical & Aerospace Engineering West Virginia University Phase Diagram (1)
CHAPTER 8 Phase Diagrams 8-1.
Thermal Equilibrium Diagrams
CENG151 Introduction to Materials Science and Selection Phase Diagrams Homework Solutions 2007.
Phase Equilibria: Solubility Limit Sucrose/Water Phase Diagram Pure Sugar Temperature (°C) Co=Composition (wt% sugar) L (liquid solution.
Chapter 9 Sections:9.2, 9.3, 9.4, 9.5.
CENG151 Introduction to Materials Science and Selection
Chapter 9: Phase Diagrams
Phase Diagrams Phase: A homogeneous portion of a system that have uniform physical and chemical characteristics. Single phase Two phases For example at.
EXPERIMENT # 9 Instructor: M.Yaqub
Phase Diagrams Chapter 10.
PHASE DIAGRAMS Phase B Phase A • When we combine two elements...
Chapter Outline: Phase Diagrams
CENG151 Introduction to Materials Science and Selection
How to calculate the total amount of  phase (both eutectic and primary)? Fraction of  phase determined by application of the lever rule across the entire.
Lecture 9 Phase Diagrams 8-1.
Chapter 9 Phase Diagrams.
Chapter ISSUES TO ADDRESS... When we combine two elements... what equilibrium state do we get? In particular, if we specify... --a composition (e.g.,
Chapter 9: Phase Diagrams
ENGR-45_Lec-22_PhaseDia-2.ppt 1 Bruce Mayer, PE Engineering-45: Materials of Engineering Bruce Mayer, PE Licensed Electrical &
Copper (Cu) FCC nm atomic radii Silver (Ag) FCC nm atomic radii Mix 50% Ag + 50% Cu, gives two solid phases (  and  )  (saturated - mostly.
1. Chapter 09: Phase Diagram 2 Introduction Phase Diagrams are road maps.
Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 1 Growth of Solid Equilibrium.
Dispersion Strengthening by Heat Treatment Chapter 11a – 4 th Edition Chapter 12a- 5 th Edition.
Thermal Equilibrium Diagram
1 ISSUES TO ADDRESS... When we combine two elements... what equilibrium state do we get? In particular, if we specify... --a composition (e.g., wt% Cu.
Ex: Phase Diagram: Water-Sugar System THE SOLUBILITY LIMIT.
Microstructure and Phase Transformations in Multicomponent Systems
PHASE DIAGRAMS THEORY AND APPLICATIONS. Some basic concepts u Phase A homogeneous region with distinct structure and physical properties In principle,
Chapter ISSUES TO ADDRESS... When we mix two elements... what equilibrium state do we get? In particular, if we specify... --a composition (e.g.,
CHE 333 Class 3 Phase Diagrams.. Why Phases? Few materials used in pure state – gold, copper, platinum etc for electrical properties or coatings. Most.
1 1 Figure 10.1 Considerations for effective dispersion strengthening: (a) The precipitate phase should be hard and discontinuous. (c)2003 Brooks/Cole,
Phase Diagrams A phase is a state of matter with the following characteristics: It has the same structure or atomic arrangement throughout It has roughly.
Mechanical & Aerospace Engineering West Virginia University 9 – Phase Diagram (2) (Phase Reactions)
1 1  Phase - Any portion including the whole of a system, which is physically homogeneous within it and bounded by a surface so that it is mechanically.
Phase Diagrams melting / production process / alloying (strength, Tm...) heat treatment microstructure material properties system (e.g. Cu-Ni) components.
EBB 512 – Phase Diagram and Equilibria Lecture 1.
The Structure and Dynamics of Solids
Phase Diagrams Binary Eutectoid Systems Iron-Iron-Carbide Phase Diagram Steels and Cast Iron 1.
Chapter ISSUES TO ADDRESS... When we combine two elements... what is the resulting equilibrium state? In particular, if we specify the composition.
Chapter ISSUES TO ADDRESS... When we combine two elements... what equilibrium state do we get? In particular, if we specify... --a composition (e.g.,
Chapter ISSUES TO ADDRESS... When we combine two __________... what is the resulting _____________state? In particular, if we specify the.
Dispersion Strengthening and Eutectic Phase Diagrams
Chemical compositions of equilibrated phases One phase areas: the determination of the chemical composition of a single phase is automatic: it has the.
Metallic Materials-Phase Diagrams
Material Science & Metallurgy Non Equilibrium Cooling
Materials Engineering
Dispersion Strengthening and Eutectic Phase Diagrams
Phase Diagrams 8-1.
Chapter 5 Phase Equilibria
Chapter 11: Phase Diagrams
Introduction to Materials Science and Engineering
CHAPTER 9: Definitions A. Solid Solution
© 2016 Cengage Learning Engineering. All Rights Reserved.
Fully Miscible Solution
CHAPTER 9: PHASE DIAGRAMS
Chapter 10: Phase Diagrams
CHE 333 Class 5 Phase Diagrams. Prov08.
2/16/2019 9:54 PM Chapter 9 Phase Diagrams Dr. Mohammad Abuhaiba, PE.
Single solid phase binary alloy -1
CHAPTER 8 Phase Diagrams 1.
CHAPTER 8 Phase Diagrams 1.
CHAPTER 8 Phase Diagrams 1.
Working with Phase Diagrams
Eutectic Type Phase Diagrams
Phase diagrams of pure substances
Phase Diagram.
CHAPTER 9: PHASE DIAGRAMS
Mechanical Properties of Isomorphous Alloys
Presentation transcript:

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 1 Development of microstructure in isomorphous alloys Equilibrium (very slow) cooling  Upon cooling from the liquidus line (in the solid + liquid phase region) formation of the solid occurs gradually.  Compositions of the solid and the liquid change gradually during cooling (as determined by the tie-line method.)  At the solidus line, nuclei grow to consume all the liquid

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 2 Non-equilibrium cooling

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 3 Development of microstructure in isomorphous alloys Non-equilibrium cooling Compositional change  diffusion SOLID Diffusion is very slow  Tie-line invalid New layers formed on top of existing grains have the equilibrium composition at that T  Formation of layered (cored) grains. LIQUID Diffusion is fast  Tie-line method works Lever rule  greater proportion of liquid phase as compared to equilibrium at the same T  Solidus line is shifted to the right (higher Ni content), solidification is complete at lower T, outer parts of grains are richer in the low- melting component (Cu). Upon heating grain boundaries will melt first. This can lead to premature mechanical failure.

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 4 Mechanical properties of isomorphous alloys Solid solution strengthening

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 5 Binary Eutectic Systems (I) alloys with limited solubility silver (Ag) / copper (Cu) radii differ The melting point of eutectic alloy is lower than that of the components (eutectic = easy to melt in Greek).

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 6 Three single phase regions  = solid solution Ag in Cu matrix,  = solid solution of Cu in Ag matrix, L = liquid Three two-phase regions (  + L,  +L,  +  ) Solvus  limit of solubility Separates one solid solution from the mixture Copper – Silver phase diagram Binary Eutectic System

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 7 Binary Eutectic System Eutectic or invariant point - Liquid + two solid phases co-exist at eutectic composition C E and eutectic temperature T E Eutectic isotherm - horizontal solidus line at T E Lead – Tin phase diagram Invariant or eutectic point Eutectic isotherm

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 8 Binary Eutectic System Eutectic reaction – transition from liquid to mixture of two solid phases,  +  at eutectic concentration C E. Two phases in equilibrium except: Three phases (L, ,  ) in equilibrium only at a few points along the eutectic isotherm. Single-phase regions are separated by 2-phase regions.

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 9 Binary Eutectic System Compositions and relative amounts of phases are determined from the same tie lines and lever rule, as for isomorphous alloys--demonstrate  C  B  A

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 10 Microstructure in eutectic alloys (I) Several types of microstructure formed in slow cooling an different compositions. Cooling of liquid lead/tin system at different compositions. In this case of lead-rich alloy (0-2 wt. % of tin) solidification proceeds in the same manner as for isomorphous alloys (e.g. Cu-Ni) that we discussed earlier. L   +L  

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 11 Microstructure in eutectic alloys (II) At compositions between room temperature solubility limit and the maximum solid solubility at the eutectic temperature,  phase nucleates as the  solid solubility is exceeded at solvus line. L  +L   + 

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 12 No changes above eutectic temperature, T E. At T E liquid transforms to  and  phases (eutectic reaction). L   +  Microstructure in eutectic alloys (III) Solidification at the eutectic composition (I)

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 13 Microstructure in eutectic alloys (IV) Solidification at the eutectic composition (II) Compositions of  and  very different  eutectic reaction involves redistribution of Pb and Sn atoms by atomic diffusion. Simultaneous formation of  and  phases results in a layered (lamellar) microstructure:called eutectic structure. Formation of eutectic structure in lead-tin system. Dark layers are lead-rich  phase. Light layers are the tin-rich  phase.

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 14 Microstructure in eutectic alloys (V) Compositions other than eutectic Primary  phase is formed in the  + L region, and the eutectic structure that includes layers of  and  phases (called eutectic  and eutectic  phases) is formed upon crossing the eutectic isotherm. L   + L   + 

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 15 Microstructure in eutectic alloys (VI) Microconstituent – element of microstructure having a distinctive structure. For case described on previous page, microstructure consists of two microconstituents, primary  phase and the eutectic structure. Although the eutectic structure consists of two phases, it is a microconstituent with distinct lamellar structure and fixed ratio of the two phases.

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 16 Relative amounts of microconstituents? Eutectic microconstituent forms from liquid having eutectic composition (61.9 wt% Sn) Treat eutectic as separate phase and apply lever rule to find relative fractions of primary  phase (18.3 wt% Sn) and eutectic structure (61.9 wt% Sn): W e = P / (P+Q) (eutectic) W  ’ = Q / (P+Q) (primary)