Defects and Diffusion

Save this PDF as:
 WORD  PNG  TXT  JPG

Size: px
Start display at page:

Download "Defects and Diffusion"

Transcription

1 Defects and Diffusion Goals for the Unit Recognize various imperfections in crystals Point imperfections Impurities Line, surface and bulk imperfections Define various diffusion mechanisms Identify factors controlling diffusion processes

2 Defects in Materials Types of defects How are defects introduced Diffusion in materials Introduction to Defects All real structures are imperfect Real material properties are often dominated by the imperfections in the structure Some materials have little long-range structure at all (glasses, some polymers)

3 Types of defects Point defects Vacancies Interstitials Impurities Extensive chemical changes Solid solutions Not a defect in intentional alloying or doping Line defects (1-dimensional) Dislocations - in metals Types of Defects, cont. Interfacial defects (2-dimensional) Surfaces - both interior (pore walls) and exterior (surface of material) Interfaces -(grain boundaries) Bulk-Volume defects (3- dimensional) Cracks, foreign inclusions, other phases (including pores)

4 Point defects Vacancy An empty atomic site Interstitial An atom somewhere other than an atomic site Self-interstitial Impurity interstitial Substitutional impurity Some foreign species on an atomic site How are point defects introduced? Some types are thermally generated Direct result of thermal vibration of the atomic array The concentration of thermally-produced defects increases exponentially with increasing temperature

5 How are point defects introduced? Added solutes (impurities or dopants) How do they get uniformly distributed? Stoichiometry changes (cation/anion ratio changes) e.g., ZrO 2-δ, Fe 1-δ O How is uniform composition accomplished? Point Defects in Metals Self Interstitial Interstitial Impurity Vacancy Substitutional Impurity

6 Ceramic Point Defects Anion Vacancy Cation Vacancy Point Defects in Ceramics Substitutional Cation Impurity Interstitial Cation Impurity Substitutional Anion Impurity Anion impurity Interstitial (not shown)

7 Point Defects in Ceramics Schottky Defect (anion and cation vacancies ) Frenkel Defect (cation vacancy + cation interstitial) Anion Frenkel (anion vacancy+anion intersititial (not shown) Solid Solution All solids have some degree of impurities dissolved in them Unintentional - called impurities Intentional - called dopants or alloying additives Solute and solvent Solvent (present in greatest amount) Solute (present in minor concentration)

8 Hume-Rothery Rules Complete mutual solid solubility will occur between two metals if: Less than 15% difference in atomic radii Both have the same crystal structure in pure form Both have similar electronegativities Both have the same valence The more deviation, the less the solubility Can also be applied roughly in simple ceramics Solution of ~30 at% Cu dissolved in solid Ni(substitutional solid solution)

9 Disordered (normal) and ordered solid solution Cu 3 Au Interstitial solid solution

10 Solution of NiO in MgO (cations of same valence) Solution of Fe 2 O 3 in FeO (altervalent cation - vacancy charge compensation) cation vacancies

11 Point defects summary Linear defects Dislocations in Metals Linear (one dimensional) defect around which some of the atoms are misaligned

12 Types of Dislocations Edge Dislocation A portion of an extra plane of atoms Screw Dislocation Helical atomic displacement around a line extending through the crystal Mixed Dislocation Some edge, some screw nature Edge dislocation

13 Burgers vector Screw dislocation

14 Mixed dislocation Shear occurs by dislocation movement producing permanent (plastic) deformation by slip Slip plane Direction of dislocation movement

15 Examples of dislocations Mixed dislocation movement to cause slip Shearing Stresses Slip occurs along densely packed directions on densely packed planes (unlikely) (likely)

16 (Plane)[Direction] pairs designate slip systems (e.g., in ccp and hcp) Dislocation movement and ductility A large number of independent slip systems are required for good ductility in polycrystalline materials so grains can deform to accomodate their neighboring grains Common in many metal structures (esp. bcc and ccp) Dislocations are very complex in ceramic structures This and complications of like charged ions encountering each other during slip make dislocation movement almost impossible in ceramics Therefore ceramics are not ductile, they are brittle

17 Major slip systems in metal structures Impediments to easy dislocation movement Impurity atoms ( solute hardening ) Intersection with other dislocations (entanglement) ( work hardening ) Grain boundaries (dislocations pile up ) Small dispersed inclusions ( precipitation hardening ) All of these affect ductility and yield strength of a metal

18 Grain boundaries and other dislocations impede the movement of dislocations causing hardening 2-D Defects Twin boundaries Grain boundaries Surfaces

19 Twinning is common in some materials Small angle grain boundaries can be thought of as arrays of dislocations

20 Grain boundaries in a polycrystalline material Some details of surface structure

21 Other types of defects Bulk (Volume defects) Pores - common feature in parts made from powders Cracks Other phases (inclusions) Pores Diffusion in Materials Q. How do changes in microstructure and chemical composition actually occur? A. Atoms must be able to move around (this is called diffusion ) Diffusion occurs in solids, liquids and gases Redistribution of non-uniform chemical species is called impurity diffusion or interdiffusion Random atomic movement can also occur in chemically uniform materials (called self diffusion )

22 Diffusion is driven by nonuniformity Concentration Profile Diffusion Diffusion is necessary for: Redistribution of chemical species Physical changes in microstructure Densification of powder compacts Deformation at high temperature (creep) Formation of solid state reaction products One kind of conductivity in ceramics (ionic)

23 Atoms in a perfect crystal would not move around because there would be no places for them to move to (all sites would be occupied)--all would be locked in place Point defects must be present in a crystal to permit atomic movement (diffusion) In a way, atomic diffusion is actually the movement of defects Diffusion Mechanisms- Vacancy Diffusion Only adjacent atoms can move into a vacancy Vacancy moves in opposite direction of atomic motion Rate depends on concentration of vacancies

24 Diffusion Mechanisms- Interstitial Diffusion Interstitial atom can move into any adjacent empty interstitial position (usually smaller atoms) Rate depends on concentration of interstitial atoms (Usually faster than vacancy diffusion) Interdiffusion forming a solid solution

25 Diffusion occurs by random jumps After many random jumps by an atom, it s displacment can be calculated by the theory of random walks Quantitative Description of Diffusion The rate of diffusion is characterized by describing atomic fluxes at particular locations in the material Critical quantities J = atomic flux (atoms/cm 2 -s) (dc/dx) = concentration gradient (atoms/cm 4 ) D = diffusion coefficient (cm 2 /s)

26 Illustration of critical quantities Interrelating the quantities Fick s first law: J = -D dc dx (negative sign indicates that the direction of diffusion flux is down the concentration gradient from high to low concentration) For steady state diffusion (local flux doesn t change with time), Fick s First Law can be solved directly

27 Non-steady state diffusion The diffusion flux at a particular point varies with time (There is a net accumulation or depletion of the diffusing species at a given location) i.e., local concentration of diffusing species changes with time as diffusion proceeds This is the most common situation Non-steady state diffusion Fick s Second Law governs 2 c t = D c 2 x Many solutions exist for particular geometries (initial and boundary conditions)

28 A Non-Steady State Situation Surface concentrati on held constant at c s Conentration and gradient change at given location with time Factors that Influence Diffusion Diffusing Species Magnitude of diffusion coefficient, D - indicates the rate at which atoms diffuse Both diffusing species and host material influence the coefficient

29 Factors influencing diffusion, cont. For example: For the host species of iron: Self diffusion at 500 C (Fe atoms moving in Fe) D = 1.1 x m 2 /s (vacancy diffusion) Carbon impurity diffusion at 500 C (C moving in Fe): D = 2.3 x m 2 /s (interstitial diffusion) This shows the contrast between rates of vacancy and interstitial diffusion Factors that Influence Diffusion Temperature Very strong effect on the diffusion coefficient: D= D o exp Q d RT (Arrhenius Equation) D o = T independent preexponential Q d = the activation energy for diffusion (J /mol, or ev/ atom) R = the gas constant, 8.31 J/ mol- K or x 10-5 ev/ atom T = absolute temperature, (K) A large activation energy results in a small D ln D = ln D o Q d R 1 T Plot lnd vs 1/T - get straight line (to measure activation energy and D o )

30 Temperature dependence of diffusion coefficient (activation energy) Carbon in α-fe Other Diffusion Paths (Besides through volume of the crystal) Atomic migration often occurs more rapidly along so-called short circuiting paths Dislocations Grain boundaries External surfaces However, there is usually small total area for this to occur - so not always important

31 Volume, grain boundary and surface diffusion Ag in Ag Diffusion and Materials Processing Properties and microstructure of materials are altered through diffusion Heat treatment is used to cause these modifications to occur in a reasonable time frame (accelerating effect of higher temp.) This is one of our most valuable tools for modifying materials

32 Summary Recognize various imperfections in crystals Point imperfections Impurities Line imperfections (dislocations) Bulk imperfections Define various diffusion mechanisms Identify factors controlling diffusion processes

Learning Objectives. Chapter Outline. Solidification of Metals. Solidification of Metals

Learning Objectives. Chapter Outline. Solidification of Metals. Solidification of Metals Learning Objectives Study the principles of solidification as they apply to pure metals. Examine the mechanisms by which solidification occurs. - Chapter Outline Importance of Solidification Nucleation

More information

TOPIC 2. STRUCTURE OF MATERIALS III

TOPIC 2. STRUCTURE OF MATERIALS III Universidad Carlos III de Madrid www.uc3m.es MATERIALS SCIENCE AND ENGINEERING TOPIC 2. STRUCTURE OF MATERIALS III Topic 2.3: Crystalline defects. Solid solutions. 1 PERFECT AND IMPERFECT CRYSTALS Perfect

More information

Imperfections: Good or Bad? Structural imperfections (defects) Compositional imperfections (impurities)

Imperfections: Good or Bad? Structural imperfections (defects) Compositional imperfections (impurities) Imperfections: Good or Bad? Structural imperfections (defects) Compositional imperfections (impurities) 1 Structural Imperfections A perfect crystal has the lowest internal energy E Above absolute zero

More information

CRYSTAL STRUCTURE, MECHANICAL BEHAVIOUR & FAILURE OF MATERIALS

CRYSTAL STRUCTURE, MECHANICAL BEHAVIOUR & FAILURE OF MATERIALS MODULE ONE CRYSTAL STRUCTURE, MECHANICAL BEHAVIOUR & FAILURE OF MATERIALS CRYSTAL STRUCTURE Metallic crystal structures; BCC, FCC and HCP Coordination number and Atomic Packing Factor (APF) Crystal imperfections:

More information

Material Science. Prof. Satish V. Kailas Associate Professor Dept. of Mechanical Engineering, Indian Institute of Science, Bangalore India

Material Science. Prof. Satish V. Kailas Associate Professor Dept. of Mechanical Engineering, Indian Institute of Science, Bangalore India Material Science Prof. Satish V. Kailas Associate Professor Dept. of Mechanical Engineering, Indian Institute of Science, Bangalore 560012 India Chapter 5. Diffusion Learning objectives: - To know the

More information

Chapter Outline Dislocations and Strengthening Mechanisms. Introduction

Chapter Outline Dislocations and Strengthening Mechanisms. Introduction Chapter Outline Dislocations and Strengthening Mechanisms What is happening in material during plastic deformation? Dislocations and Plastic Deformation Motion of dislocations in response to stress Slip

More information

Point Defects. Vacancies are the most important form. Vacancies Self-interstitials

Point Defects. Vacancies are the most important form. Vacancies Self-interstitials Grain Boundaries 1 Point Defects 2 Point Defects A Point Defect is a crystalline defect associated with one or, at most, several atomic sites. These are defects at a single atom position. Vacancies Self-interstitials

More information

Dislocations and Plastic Deformation

Dislocations and Plastic Deformation Dislocations and Plastic Deformation Edge and screw are the two fundamental dislocation types. In an edge dislocation, localized lattice distortion exists along the end of an extra half-plane of atoms,

More information

Kinetics. Rate of change in response to thermodynamic forces

Kinetics. Rate of change in response to thermodynamic forces Kinetics Rate of change in response to thermodynamic forces Deviation from local equilibrium continuous change T heat flow temperature changes µ atom flow composition changes Deviation from global equilibrium

More information

Diffusion in Solids. Why is it an important part of processing? How can the rate of diffusion be predicted for some simple cases?

Diffusion in Solids. Why is it an important part of processing? How can the rate of diffusion be predicted for some simple cases? Diffusion in Solids ISSUES TO ADDRESS... How does diffusion occur? Why is it an important part of processing? How can the rate of diffusion be predicted for some simple cases? How does diffusion depend

More information

CHAPTER 5 IMPERFECTIONS IN SOLIDS PROBLEM SOLUTIONS ev /atom = exp. kt ( =

CHAPTER 5 IMPERFECTIONS IN SOLIDS PROBLEM SOLUTIONS ev /atom = exp. kt ( = CHAPTER 5 IMPERFECTIONS IN SOLIDS PROBLEM SOLUTIONS Vacancies and Self-Interstitials 5.1 Calculate the fraction of atom sites that are vacant for copper at its melting temperature of 1084 C (1357 K). Assume

More information

Impurities in Solids. Crystal Electro- Element R% Structure negativity Valence

Impurities in Solids. Crystal Electro- Element R% Structure negativity Valence 4-4 Impurities in Solids 4.4 In this problem we are asked to cite which of the elements listed form with Ni the three possible solid solution types. For complete substitutional solubility the following

More information

Point Defects in Metals

Point Defects in Metals CHAPTER 5 IMPERFECTIONS IN SOLIDS PROBLEM SOLUTIONS Point Defects in Metals 5.1 Calculate the fraction of atom sites that are vacant for lead at its melting temperature of 327 C (600 K). Assume an energy

More information

CHAPTER 5 IMPERFECTIONS IN SOLIDS PROBLEM SOLUTIONS

CHAPTER 5 IMPERFECTIONS IN SOLIDS PROBLEM SOLUTIONS CHAPTER 5 IMPERFECTIONS IN SOLIDS PROBLEM SOLUTIONS Vacancies and Self-Interstitials 5.1 Calculate the fraction of atom sites that are vacant for copper at its melting temperature of 1084 C (1357 K). Assume

More information

Chapter 5: Diffusion

Chapter 5: Diffusion Chapter 5: Diffusion ISSUES TO ADDRESS... How does diffusion occur? Why is it an important part of processing? How can the rate of diffusion be predicted for some simple cases? How does diffusion depend

More information

Free Electron Model What kind of interactions hold metal atoms together? How does this explain high electrical and thermal conductivity?

Free Electron Model What kind of interactions hold metal atoms together? How does this explain high electrical and thermal conductivity? Electrical Good conductors of heat & electricity Create semiconductors Oxides are basic ionic solids Aqueous cations (positive charge, Lewis acids) Reactivity increases downwards in family Mechanical Lustrous

More information

Free Electron Model What kind of interactions hold metal atoms together? How does this explain high electrical and thermal conductivity?

Free Electron Model What kind of interactions hold metal atoms together? How does this explain high electrical and thermal conductivity? Electrical Good conductors of heat & electricity Create semiconductors Oxides are basic ionic solids Aqueous cations (positive charge, Lewis acids) Reactivity increases downwards in family Free Electron

More information

Definition and description of different diffusion terms

Definition and description of different diffusion terms Definition and description of different diffusion terms efore proceeding further, it is necessary to introduce different terms frequently used in diffusion studies. Many terms will be introduced, which

More information

Short-Circuit Diffusion L6 11/14/06

Short-Circuit Diffusion L6 11/14/06 Short-Circuit Diffusion in Crystals 1 Today s topics: Diffusion spectrum in defective crystals Dislocation core structure and dislocation short circuits Grain boundary structure Grain boundary diffusion

More information

Dislocations in Materials. Dislocations in Materials

Dislocations in Materials. Dislocations in Materials Pose the following case scenario: Consider a block of crystalline material on which forces are applied. Top Force (111) parallel with top surface Bottom Force Sum Sum of of the the applied forces give

More information

Module-6. Dislocations and Strengthening Mechanisms

Module-6. Dislocations and Strengthening Mechanisms Module-6 Dislocations and Strengthening Mechanisms Contents 1) Dislocations & Plastic deformation and Mechanisms of plastic deformation in metals 2) Strengthening mechanisms in metals 3) Recovery, Recrystallization

More information

Engineering 45: Properties of Materials Final Exam May 9, 2012 Name: Student ID number:

Engineering 45: Properties of Materials Final Exam May 9, 2012 Name: Student ID number: Engineering 45: Properties of Materials Final Exam May 9, 2012 Name: Student ID number: Instructions: Answer all questions and show your work. You will not receive partial credit unless you show your work.

More information

Point Defects LATTICE VACANCIES 585. DIFFUSION 588 Metals 591. COLOR CENTERS 592 F centers 592 Other centers in alkali halides 593 PROBLEMS 595

Point Defects LATTICE VACANCIES 585. DIFFUSION 588 Metals 591. COLOR CENTERS 592 F centers 592 Other centers in alkali halides 593 PROBLEMS 595 ch20.qxd 9/22/04 5:27 PM Page 583 20 Point Defects LATTICE VACANCIES 585 DIFFUSION 588 Metals 591 COLOR CENTERS 592 F centers 592 Other centers in alkali halides 593 PROBLEMS 595 1. Frenkel defects 595

More information

1. Use the Ellingham Diagram (reproduced here as Figure 0.1) to answer the following.

1. Use the Ellingham Diagram (reproduced here as Figure 0.1) to answer the following. 315 Problems 1. Use the Ellingham Diagram (reproduced here as Figure 0.1) to answer the following. (a) Find the temperature and partial pressure of O 2 where Ni(s), Ni(l), and NiO(s) are in equilibrium.

More information

C h a p t e r 4 : D e f e c t s i n C r y s t a l s

C h a p t e r 4 : D e f e c t s i n C r y s t a l s C h a p t e r 4 : D e f e c t s i n C r y s t a l s...perfection's a gift of The gods, few can boast they possess it - and most Of you, my dears, don't. - Ovid, The Art of Love Chapter 4: Defects in Crystals...

More information

3. Anisotropic blurring by dislocations

3. Anisotropic blurring by dislocations Dynamical Simulation of EBSD Patterns of Imperfect Crystals 1 G. Nolze 1, A. Winkelmann 2 1 Federal Institute for Materials Research and Testing (BAM), Berlin, Germany 2 Max-Planck- Institute of Microstructure

More information

Mechanical Properties

Mechanical Properties Mechanical Properties Elastic deformation Plastic deformation Fracture II. Stable Plastic Deformation S s y For a typical ductile metal: I. Elastic deformation II. Stable plastic deformation III. Unstable

More information

Chapter 18: Electrical Properties

Chapter 18: Electrical Properties Chapter 18: Electrical Properties ISSUES TO ADDRESS... How are electrical conductance and resistance characterized? What are the physical phenomena that distinguish conductors, semiconductors, and insulators?

More information

a) The self-diffusion coefficient of a metal with cubic structure can be expressed as

a) The self-diffusion coefficient of a metal with cubic structure can be expressed as EXERCISES KJM5120 Chapter 5; Diffusion 1. Random (self) diffusion a) The self-diffusion coefficient of a metal with cubic structure can be expressed as 1 n D = s 6 t 2 where n/t represents the jump frequency

More information

STRENGTHENING MECHANISM IN METALS

STRENGTHENING MECHANISM IN METALS Background Knowledge Yield Strength STRENGTHENING MECHANISM IN METALS Metals yield when dislocations start to move (slip). Yield means permanently change shape. Slip Systems Slip plane: the plane on which

More information

A DISLOCATION MODEL FOR THE PLASTIC DEFORMATION OF FCC METALS AN ANALYSIS OF PURE COPPER AND AUSTENITIC STEEL

A DISLOCATION MODEL FOR THE PLASTIC DEFORMATION OF FCC METALS AN ANALYSIS OF PURE COPPER AND AUSTENITIC STEEL A DISLOCATION MODEL FOR THE PLASTIC DEFORMATION OF FCC METALS AN ANALYSIS OF PURE COPPER AND AUSTENITIC STEEL Background In the bcc model for work hardening in single phase materials, see (6), it is assumed

More information

Chapter Outline How do atoms arrange themselves to form solids?

Chapter Outline How do atoms arrange themselves to form solids? Chapter Outline How do atoms arrange themselves to form solids? Fundamental concepts and language Unit cells Crystal structures Face-centered cubic Body-centered cubic Hexagonal close-packed Close packed

More information

Objective To study the time and temperature variations in the hardness of Al-4% Cu alloy on isothermal aging.

Objective To study the time and temperature variations in the hardness of Al-4% Cu alloy on isothermal aging. EXPERIMENT 8 PRECIPITATION HARDENING IN 2024 ALUMINUM Objective To study the time and temperature variations in the hardness of Al-4% Cu alloy on isothermal aging. Introduction Materials can be hardened

More information

Chapter 12: Structures & Properties of Ceramics

Chapter 12: Structures & Properties of Ceramics Chapter 12: Structures & Properties of Ceramics ISSUES TO ADDRESS... Review of structures for ceramics How are impurities accommodated in the ceramic lattice? In what ways are ceramic phase diagrams similar

More information

Chapter 10: Phase Diagrams

Chapter 10: Phase Diagrams hapter 10: Phase Diagrams Show figures 10-1 and 10-3, and discuss the difference between a component and a phase. A component is a distinct chemical entity, such as u, Ni, NiO or MgO. A phase is a chemically

More information

Phase Transformations in Metals Tuesday, December 24, 2013 Dr. Mohammad Suliman Abuhaiba, PE 1

Phase Transformations in Metals Tuesday, December 24, 2013 Dr. Mohammad Suliman Abuhaiba, PE 1 Ferrite - BCC Martensite - BCT Fe 3 C (cementite)- orthorhombic Austenite - FCC Chapter 10 Phase Transformations in Metals Tuesday, December 24, 2013 Dr. Mohammad Suliman Abuhaiba, PE 1 Why do we study

More information

Chapter Outline: Failure

Chapter Outline: Failure Chapter Outline: Failure How do Materials Break? Ductile vs. brittle fracture Principles of fracture mechanics Stress concentration Impact fracture testing Fatigue (cyclic stresses) Cyclic stresses, the

More information

The Structure of Materials

The Structure of Materials The Structure of Materials Samuel M. Allen Edwin L. Thomas Massachusetts Institute of Technology Cambridge, Massachusetts / John Wiley & Sons, Inc. New York Chichester Weinheim Brisbane Singapore Toronto

More information

LN Introduction to Solid State Chemistry. Lecture Notes No. 9 DIFFUSION

LN Introduction to Solid State Chemistry. Lecture Notes No. 9 DIFFUSION 3.091 Introduction to Solid State Chemistry Lecture Notes No. 9 DIFFUSION * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Sources for Further Reading:

More information

Creep and High Temperature Failure. Creep and High Temperature Failure. Creep Curve. Outline

Creep and High Temperature Failure. Creep and High Temperature Failure. Creep Curve. Outline Creep and High Temperature Failure Outline Creep and high temperature failure Creep testing Factors affecting creep Stress rupture life time behaviour Creep mechanisms Example Materials for high creep

More information

J = D C A C B x A x B + D C A C. = x A kg /m 2

J = D C A C B x A x B + D C A C. = x A kg /m 2 1. (a) Compare interstitial and vacancy atomic mechanisms for diffusion. (b) Cite two reasons why interstitial diffusion is normally more rapid than vacancy diffusion. (a) With vacancy diffusion, atomic

More information

- Slip by dislocation movement - Deformation produced by motion of dislocations (Orowan s Eq.)

- Slip by dislocation movement - Deformation produced by motion of dislocations (Orowan s Eq.) Lecture #12 - Critical resolved shear stress Dr. Haydar Al-Ethari - Slip y dislocation movement - Deformation produced y motion of dislocations (Orowan s Eq.) References: 1- Derek Hull, David Bacon, (2001),

More information

Two marks questions and answers. 1. what is a Crystal? (or) What are crystalline materials? Give examples

Two marks questions and answers. 1. what is a Crystal? (or) What are crystalline materials? Give examples UNIT V CRYSTAL PHYSICS PART-A Two marks questions and answers 1. what is a Crystal? (or) What are crystalline materials? Give examples Crystalline solids (or) Crystals are those in which the constituent

More information

Planar Defects in Materials. Planar Defects in Materials

Planar Defects in Materials. Planar Defects in Materials Classification of Defects in Solids: Planar defects: Stacking faults o {311} defects in Si o Inversion domain boundaries o Antiphase boundaries (e.g., super dislocations): analogous to partials but in

More information

The University of Jordan School of Engineering Chemical Engineering Department

The University of Jordan School of Engineering Chemical Engineering Department The University of Jordan School of Engineering Chemical Engineering Department 0905351 Engineering Materials Science Second Semester 2016/2017 Course Catalog 3 Credit hours.all engineering structures and

More information

Chapter 10, Phase Transformations

Chapter 10, Phase Transformations Chapter Outline: Phase Transformations Heat Treatment (time and temperature) Microstructure Kinetics of phase transformations Homogeneous and heterogeneous nucleation Growth, rate of the phase transformation

More information

Unit-1 THE SOLID STATE QUESTIONS VSA QUESTIONS (1 - MARK QUESTIONS)

Unit-1 THE SOLID STATE QUESTIONS VSA QUESTIONS (1 - MARK QUESTIONS) Unit-1 THE SOLID STATE QUESTIONS VSA QUESTIONS (1 - MARK QUESTIONS) 1. What are anistropic substances. 2. Why are amorphous solids isotropic in nature?. Why glass is regarded as an amorphous solid? 4.

More information

Section 4: Thermal Oxidation. Jaeger Chapter 3. EE143 - Ali Javey

Section 4: Thermal Oxidation. Jaeger Chapter 3. EE143 - Ali Javey Section 4: Thermal Oxidation Jaeger Chapter 3 Properties of O Thermal O is amorphous. Weight Density =.0 gm/cm 3 Molecular Density =.3E molecules/cm 3 O Crystalline O [Quartz] =.65 gm/cm 3 (1) Excellent

More information

Point defects. process complicated. Now we shall discuss on defects, which will help to understand the atomic mechanism of diffusion.

Point defects. process complicated. Now we shall discuss on defects, which will help to understand the atomic mechanism of diffusion. Point defects Diffusion of elements is possible because of the presence of defects. For example, substitutional diffusion occurs because of exchange of an atom with acancies. Further, impurities are present

More information

CHAPTER 5 DIFFUSION PROBLEM SOLUTIONS

CHAPTER 5 DIFFUSION PROBLEM SOLUTIONS CHAPTER 5 DIFFUSION PROBLEM SOLUTIONS 5.5 (a) Briefly explain the concept of a driving force. (b) What is the driving force for steady-state diffusion? (a) The driving force is that which compels a reaction

More information

3.40 Sketch within a cubic unit cell the following planes: (a) (01 1 ) (b) (112 ) (c) (102 ) (d) (13 1) Solution

3.40 Sketch within a cubic unit cell the following planes: (a) (01 1 ) (b) (112 ) (c) (102 ) (d) (13 1) Solution 3.40 Sketch within a cubic unit cell the following planes: (a) (01 1 ) (b) (11 ) (c) (10 ) (d) (13 1) The planes called for are plotted in the cubic unit cells shown below. 3.41 Determine the Miller indices

More information

1. Introduction. What is implantation? Advantages

1. Introduction. What is implantation? Advantages Ion implantation Contents 1. Introduction 2. Ion range 3. implantation profiles 4. ion channeling 5. ion implantation-induced damage 6. annealing behavior of the damage 7. process consideration 8. comparison

More information

Recrystallization Theoretical & Practical Aspects

Recrystallization Theoretical & Practical Aspects Theoretical & Practical Aspects 27-301, Microstructure & Properties I Fall 2006 Supplemental Lecture A.D. Rollett, M. De Graef Materials Science & Engineering Carnegie Mellon University 1 Objectives The

More information

Materials Issues in Fatigue and Fracture. 5.1 Fundamental Concepts 5.2 Ensuring Infinite Life 5.3 Failure 5.4 Summary

Materials Issues in Fatigue and Fracture. 5.1 Fundamental Concepts 5.2 Ensuring Infinite Life 5.3 Failure 5.4 Summary Materials Issues in Fatigue and Fracture 5.1 Fundamental Concepts 5.2 Ensuring Infinite Life 5.3 Failure 5.4 Summary 1 A simple view of fatigue 1. Will a crack nucleate? 2. Will it grow? 3. How fast will

More information

Twins & Dislocations in HCP Textbook & Paper Reviews. Cindy Smith

Twins & Dislocations in HCP Textbook & Paper Reviews. Cindy Smith Twins & Dislocations in HCP Textbook & Paper Reviews Cindy Smith Motivation Review: Outline Crystal lattices (fcc, bcc, hcp) Fcc vs. hcp stacking sequences Cubic {hkl} naming Hcp {hkil} naming Twinning

More information

Precipitation Hardening. Outline. Precipitation Hardening. Precipitation Hardening

Precipitation Hardening. Outline. Precipitation Hardening. Precipitation Hardening Outline Dispersion Strengthening Mechanical Properties of Steel Effect of Pearlite Particles impede dislocations. Things that slow down/hinder/impede dislocation movement will increase, y and TS And also

More information

Module 31. Heat treatment of steel I. Lecture 31. Heat treatment of steel I

Module 31. Heat treatment of steel I. Lecture 31. Heat treatment of steel I Module 31 Heat treatment of steel I Lecture 31 Heat treatment of steel I 1 Keywords : Transformation characteristics of eutectoid steel, isothermal diagram, microstructures of pearlite, bainite and martensite,

More information

Chem 241. Lecture 19. UMass Amherst Biochemistry... Teaching Initiative

Chem 241. Lecture 19. UMass Amherst Biochemistry... Teaching Initiative Chem 241 Lecture 19 UMass Amherst Biochemistry... Teaching Initiative Announcement March 26 Second Exam Recap Water Redox Comp/Disproportionation Latimer Diagram Frost Diagram Pourbaix Diagram... 2 Ellingham

More information

Electrical conduction in ceramics

Electrical conduction in ceramics Laurea Magistrale in Scienza dei Materiali Materiali Inorganici Funzionali Electrical conduction in ceramics Prof. Antonella Glisenti - Dip. Scienze Chimiche - Università degli Studi di Padova Conductivity

More information

Lectures on: Introduction to and fundamentals of discrete dislocations and dislocation dynamics. Theoretical concepts and computational methods

Lectures on: Introduction to and fundamentals of discrete dislocations and dislocation dynamics. Theoretical concepts and computational methods Lectures on: Introduction to and fundamentals of discrete dislocations and dislocation dynamics. Theoretical concepts and computational methods Hussein M. Zbib School of Mechanical and Materials Engineering

More information

The Plastic Regime. Processes in Structural Geology & Tectonics. Ben van der Pluijm. WW Norton+Authors, unless noted otherwise 3/4/ :11

The Plastic Regime. Processes in Structural Geology & Tectonics. Ben van der Pluijm. WW Norton+Authors, unless noted otherwise 3/4/ :11 The Plastic Regime Processes in Structural Geology & Tectonics Ben van der Pluijm WW Norton+Authors, unless noted otherwise 3/4/2017 17:11 We Discuss The Plastic Regime Strain rate Viscosity Crystal defects

More information

a. 50% fine pearlite, 12.5% bainite, 37.5% martensite. 590 C for 5 seconds, 350 C for 50 seconds, cool to room temperature.

a. 50% fine pearlite, 12.5% bainite, 37.5% martensite. 590 C for 5 seconds, 350 C for 50 seconds, cool to room temperature. Final Exam Wednesday, March 21, noon to 3:00 pm (160 points total) 1. TTT Diagrams A U.S. steel producer has four quench baths, used to quench plates of eutectoid steel to 700 C, 590 C, 350 C, and 22 C

More information

LEARNING OBJECTIVES FUNDAMENTALS PREFACE

LEARNING OBJECTIVES FUNDAMENTALS PREFACE FUNDAMENTALS PREFACE Accreditation standards, as mandated by many engineering accreditation organizations, now include outcome assessment components. Often one of these components includes the delineation

More information

Lecture 11. Ductile Deformation and Microstructures. Earth Structure (2 nd Edition), 2004 W.W. Norton & Co, New York Slide show by Ben van der Pluijm

Lecture 11. Ductile Deformation and Microstructures. Earth Structure (2 nd Edition), 2004 W.W. Norton & Co, New York Slide show by Ben van der Pluijm Lecture 11 Ductile Deformation and Microstructures Earth Structure (2 nd Edition), 2004 W.W. Norton & Co, New York Slide show by Ben van der Pluijm Crustal Fault Model EarthStructure (2 nd ed) 2 Brittle

More information

Section 4: Thermal Oxidation. Jaeger Chapter 3

Section 4: Thermal Oxidation. Jaeger Chapter 3 Section 4: Thermal Oxidation Jaeger Chapter 3 Properties of O Thermal O is amorphous. Weight Density =.0 gm/cm 3 Molecular Density =.3E molecules/cm 3 O Crystalline O [Quartz] =.65 gm/cm 3 (1) Excellent

More information

Free Sintering or Hot Pressing? A Decision Support

Free Sintering or Hot Pressing? A Decision Support Free Sintering or Hot Pressing? A Decision Support Christian H. Kühl Diamond Tool Consulting Neuhofer Straße 13b, 24558 Henstedt-Ulzburg christian.h.kuehl@gmx.de www.diamond-tool-consulting.de Abstract

More information

Packing of atoms in solids

Packing of atoms in solids MME131: Lecture 6 Packing of atoms in solids A. K. M. B. Rashid Professor, Department of MME BUET, Dhaka Today s topics Atomic arrangements in solids Points, directions and planes in unit cell References:

More information

ENGINEERING MATERIALS LECTURE #4

ENGINEERING MATERIALS LECTURE #4 ENGINEERING MATERIALS LECTURE #4 Chapter 3: The Structure of Crystalline Solids Topics to Cover What is the difference in atomic arrangement between crystalline and noncrystalline solids? What features

More information

Chapter 3 Crystal Interfaces and Microstructure

Chapter 3 Crystal Interfaces and Microstructure Chapter 3 Crystal Interfaces and Microstructure Interfacial free energy Solid / vapor interfaces Boundaries in single-phase solids Interphase interfaces in solids Interface migration Interfacial Free Energy

More information

DOE FUNDAMENTALS HANDBOOK

DOE FUNDAMENTALS HANDBOOK DOE-HDBK-1017/1-93 JANUARY 1993 DOE FUNDAMENTALS HANDBOOK MATERIAL SCIENCE Volume 1 of 2 U.S. Department of Energy Washington, D.C. 20585 FSC-6910 Distribution Statement A. Approved for public release;

More information

Engineering Materials

Engineering Materials Engineering Materials Heat Treatments of Ferrous Alloys Annealing Processes The term annealing refers to a heat treatment in which a material is exposed to an elevated temperature for an extended time

More information

Laurea Magistrale in Scienza dei Materiali. Materiali Inorganici Funzionali. Electrolytes: Ceria

Laurea Magistrale in Scienza dei Materiali. Materiali Inorganici Funzionali. Electrolytes: Ceria Laurea Magistrale in Scienza dei Materiali Materiali Inorganici Funzionali Electrolytes: Ceria Prof. Antonella Glisenti - Dip. Scienze Chimiche - Università degli Studi di Padova Bibliography 1. N.Q. Minh,

More information

Introduction to Dislocation Mechanics

Introduction to Dislocation Mechanics Introduction to Dislocation Mechanics What is Dislocation Mechanics? (as meant here) The study of the stress state and deformation of continua whose elastic response is mediated by the nucleation, presence,

More information

1) Fracture, ductile and brittle fracture 2) Fracture mechanics

1) Fracture, ductile and brittle fracture 2) Fracture mechanics Module-08 Failure 1) Fracture, ductile and brittle fracture 2) Fracture mechanics Contents 3) Impact fracture, ductile-to-brittle transition 4) Fatigue, crack initiation and propagation, crack propagation

More information

Materials Science Handbook: Volume 1 Structure and Properties of Metals 5 PDH / 5 CE Hours

Materials Science Handbook: Volume 1 Structure and Properties of Metals 5 PDH / 5 CE Hours Materials Science Handbook: Volume 1 Structure and Properties of Metals 5 PDH / 5 CE Hours DOE Fundamentals Handbook Material Science Volume 1 of 2 DOE-HDBK-1017/1-93 PDH Academy PO Box 449 Pewaukee, WI

More information

Fundamental concepts and language Unit cells Crystal structures! Face-centered cubic! Body-centered cubic! Hexagonal close-packed Close packed

Fundamental concepts and language Unit cells Crystal structures! Face-centered cubic! Body-centered cubic! Hexagonal close-packed Close packed Fundamental concepts and language Unit cells Crystal structures! Face-centered cubic! Body-centered cubic! Hexagonal close-packed Close packed crystal structures Density computations Crystal structure

More information

Phase Diagrams of Pure Substances Predicts the stable phase as a function of P total and T. Example: water can exist in solid, liquid and vapor

Phase Diagrams of Pure Substances Predicts the stable phase as a function of P total and T. Example: water can exist in solid, liquid and vapor PHASE DIAGRAMS Phase a chemically and structurally homogenous region of a material. Region of uniform physical and chemical characteristics. Phase boundaries separate two distinct phases. A single phase

More information

Fundamentals of Material Science

Fundamentals of Material Science PDHonline Course M153 (10 PDH) Fundamentals of Material Science Instructor: Frank Li, Ph.D. 2012 PDH Online PDH Center 5272 Meadow Estates Drive Fairfax, VA 22030-6658 Phone & Fax: 703-988-0088 www.pdhonline.org

More information

Chapter 7 Mass Transfer

Chapter 7 Mass Transfer Chapter 7 Mass Transfer Mass transfer occurs in mixtures containing local concentration variation. For example, when dye is dropped into a cup of water, mass-transfer processes are responsible for the

More information

Module #25. Martensitic Transformations and Strengthening

Module #25. Martensitic Transformations and Strengthening Module #25 Martensitic Transformations and Strengthening READING LIST DIETER: Ch. 6, pp. 226-228. Chapter 11 in Meyers & Chawla. Chapter 13 in P. Haasen, Physical Metallurgy, 3 rd Edition, Cambridge University

More information

Ph.D. Admission 20XX-XX Semester X

Ph.D. Admission 20XX-XX Semester X Ph.D. Admission 20XX-XX Semester X Written Examination Materials Science & Engineering Department, IIT Kanpur Date of Examination: XX XXXX 20XX Timing: XX:XX XX:XX XX Application# Please read these instructions

More information

Diffusion and Fick s law. Prof.P. Ravindran, Department of Physics, Central University of Tamil Nadu, India

Diffusion and Fick s law. Prof.P. Ravindran, Department of Physics, Central University of Tamil Nadu, India Diffusion and Fick s law 1 Prof.P. Ravindran, Department of Physics, Central University of Tamil Nadu, India http://folk.uio.no/ravi/pmat2013 Diffusion, flux, and Fick s law 2 Diffusion: (1) motion of

More information

Intrinsic Defects in Semiconductors

Intrinsic Defects in Semiconductors Intrinsic Defects in Semiconductors In all previous consideration of crystal structure and crystal growth, for simplicity it has been assumed that the silicon crystal lattice is entirely free of defects.

More information

Lecture 31-36: Questions:

Lecture 31-36: Questions: Lecture 31-36: Heat treatment of steel: T-T-T diagram, Pearlitic, Martensitic & Bainitic transformation, effect of alloy elements on phase diagram & TTT diagram, CCT diagram, Annealing, normalizing, hardening

More information

Metals I. Anne Mertens

Metals I. Anne Mertens "MECA0139-1: Techniques "MECA0462-2 additives : et Materials 3D printing", Selection", ULg, 19/09/2017 25/10/2016 Metals I Anne Mertens Introduction Outline Metallic materials Materials Selection: case

More information

Unit 1 The Solid State

Unit 1 The Solid State Points to Remember Amorphous and Crystalline Solids Unit 1 The Solid State Amorphous- short range order, Irregular shape eg-glass Crystalline Solids- long range order, regular shape eg : NaCl Molecular

More information

1.10 Close packed structures cubic and hexagonal close packing

1.10 Close packed structures cubic and hexagonal close packing 1.9 Description of crystal structures The most common way for describing crystal structure is to refer the structure to the unit cell. The structure is given by the size and shape of the cell and the position

More information

REVISED PAGES IMPORTANT TERMS AND CONCEPTS REFERENCES QUESTIONS AND PROBLEMS. 166 Chapter 6 / Mechanical Properties of Metals

REVISED PAGES IMPORTANT TERMS AND CONCEPTS REFERENCES QUESTIONS AND PROBLEMS. 166 Chapter 6 / Mechanical Properties of Metals 1496T_c06_131-173 11/16/05 17:06 Page 166 166 Chapter 6 / Mechanical Properties of Metals IMPORTANT TERMS AND CONCEPTS Anelasticity Design stress Ductility Elastic deformation Elastic recovery Engineering

More information

Chapter 9 Heat treatment (This chapter covers selective sections in Callister Chap. 9, 10 &11)

Chapter 9 Heat treatment (This chapter covers selective sections in Callister Chap. 9, 10 &11) Chapter 9 Heat treatment (This chapter covers selective sections in Callister Chap. 9, 10 &11) Study theme outcomes: After studying this chapter, students should or should be able to: - know and understand

More information

ASTM Conference, Feb , Hyderabad, India

ASTM Conference, Feb , Hyderabad, India ASTM Conference, Feb 6 2013, Hyderabad, India Effect of Hydrogen on Dimensional Changes of Zirconium and the Influence of Alloying Elements: First-principles and Classical Simulations of Point Defects,

More information

Introduction to Engineering Materials ENGR2000 Chapter 19: Thermal Properties. Dr. Coates

Introduction to Engineering Materials ENGR2000 Chapter 19: Thermal Properties. Dr. Coates Introduction to Engineering Materials ENGR2000 Chapter 19: Thermal Properties Dr. Coates Chapter 19: Thermal Properties ISSUES TO ADDRESS... How do materials respond to the application of heat? How do

More information

Mechanical Properties of Metals. Goals of this unit

Mechanical Properties of Metals. Goals of this unit Mechanical Properties of Metals Instructor: Joshua U. Otaigbe Iowa State University Goals of this unit Quick survey of important metal systems Detailed coverage of basic mechanical properties, especially

More information

Applications of Powder Densification Maps to Direct Metal SLS/HIP Processing

Applications of Powder Densification Maps to Direct Metal SLS/HIP Processing Applications of Powder Densification Maps to Direct Metal SLS/HIP Processing Martin Wohlert, David L. Bourell *, Suman Das*, Joseph J. Beaman * Texas Materials Institute Laboratory for Freeform Fabrication

More information

Non-crystalline Materials

Non-crystalline Materials Noncrystalline (or amorphous) solids by definition means atoms are stacked in irregular, random patterns. The general term for non-crystallline solids with compositions comparable to those of crystalline

More information

Donald Neamen 물리전자 / 김삼동 1-1

Donald Neamen 물리전자 / 김삼동 1-1 An Introduction to Semiconductor Devices Donald Neamen Images and illustrations from supplements of An Introduction to Semiconductor Devices, 4 th Ed., Mc Graw Hill were used for this lecture materials.

More information

Introduction to the phase diagram Uses and limitations of phase diagrams Classification of phase diagrams Construction of phase diagrams

Introduction to the phase diagram Uses and limitations of phase diagrams Classification of phase diagrams Construction of phase diagrams Prof. A.K.M.B. Rashid Department of MME BUET, Dhaka Concept of alloying Classification of alloys Introduction to the phase diagram Uses and limitations of phase diagrams Classification of phase diagrams

More information

ELECTRICAL RESISTIVITY AS A FUNCTION OF TEMPERATURE

ELECTRICAL RESISTIVITY AS A FUNCTION OF TEMPERATURE ELECTRICAL RESISTIVITY AS A FUNCTION OF TEMPERATURE Introduction The ability of materials to conduct electric charge gives us the means to invent an amazing array of electrical and electronic devices,

More information

SOLID-STATE STRUCTURE.. FUNDAMENTALS

SOLID-STATE STRUCTURE.. FUNDAMENTALS SOLID-STATE STRUCTURE.. FUNDAMENTALS Metallic Elements & Sphere Packing, Unit Celis, Coordination Number, Ionic Structures Stoichiometry PRELAB ASSIGNMENT Properties of Shapes & Patterns following question

More information

Irradiation Assisted Stress Corrosion Cracking. By Topan Setiadipura [09M51695] (Obara Lab., Nuclear Engineering Dept., Tokyo Tech.

Irradiation Assisted Stress Corrosion Cracking. By Topan Setiadipura [09M51695] (Obara Lab., Nuclear Engineering Dept., Tokyo Tech. Introduction Short Review on Irradiation Assisted Stress Corrosion Cracking By Topan Setiadipura [09M51695] (Obara Lab., Nuclear Engineering Dept., Tokyo Tech.) Irradiation-assisted stress-corrosion cracking

More information

NO NEGATIVE MARKINGS. SECTIONS A

NO NEGATIVE MARKINGS. SECTIONS A Application No. Department of Materials Science & Engineering, IIT Kanpur **********: Written Examination: ******* Examination: ********* Duration: 1 hour Maximum Marks: 60 Please read these instructions

More information