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ENGR 224, Materials Science Lecturer: Scott Kessler, P.E., Ph.D., ASNT Level III

email: skessler@coloradomesa.edu phone: 970-248-1673 office, 816-392-9470 cell

Location: Archuleta Engineering Center (AEC) 205 Time: Tuesday & Thursday, 11:00 to 12:15 am

Attendance is mandatory

Make-ups given only for emergencies Discuss potential conflicts beforehand.

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ENGR 224: Introduction to Materials Science & Engineering

Course Objective... Introduce fundamental concepts in Materials Science

You will learn about: • material structure • how structure dictates properties • how processing can change structure

This course will help you to: • use materials properly • realize new design opportunities

with materials

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Purpose: To learn more about materials by relating lecture material with observations. Also to learn to properly formulate and write engineering reports and proposals.

Location: Archuleta Engineering Center (AEC)

Scheduled as Needed

LABORATORY SECTIONS

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Office Hours

Activities: • Discuss homework, quizzes, exams • Discuss lectures, book

1:00 to 2:00 am Monday & 11:00 to 12:00 am Wednesday 12:30 to 2:00 pm Tuesday & Thursday

@ AEC 216 other times by appointment

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Required text: • Materials Science and Engineering: An Introduction

W.D. Callister & D.G. Rethwisch, Jr., 8th edition, John Wiley and Sons, Inc. (2010).

COURSE MATERIALS

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Text Website: http://www.wiley.com/college/callister •  VMSE for 3D visualization and manipulation of atomic structures •  Mechanical Engineering and Biomaterials online support modules •  Case studies of materials usage •  Extended learning objectives •  Self-assessment exercises

Course Website: http://www.coloradomesa.edu/~skessler • Syllabus • Lecture notes • Answer keys • Grades

COURSE WEBSITES

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Website: http://www.wileyplus.com/college/callister Student Companion Site

•  Users can manipulate molecules and crystals to better visualize atomic structures

•  Unit cells such as BCC, FCC, HCP •  Crystallographic planes, directions, and defects •  Polymer repeat units and molecules

•  Diffusion computations

Virtual Materials Science & Engineering (VMSE)

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GRADING Homework & Quizzes 15%

Homework is given due dates, 50% off if received next class Quizzes based on core homework problems (only given if deemed necessary)

3 Tests @ 20% per test

Final 25% Scheduled for Tuesday, May 8th at 10:00 to 11:50 am

Material covered: comprehensive

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TENTATIVE SCHEDULE Week

1 2&3 4&5 6&7

8 9

10 11&12 13&14 15&16

if possible

Topic General Intro; Atomic Bonding

Crystalline Structures; Imperfections; Diffusion Mechanical Properties; Test 1; Strengthening

Failure; Phase Diagrams Transformation

Applications & Processing of Metal Alloys; Test 2 Struc., Prop., Proc., Applic. of Ceramics Struc., Prop. of Polymers; Composites

Corrosion; Electrical Props Test3; Review; Final

Magnetic & Optical Prop. Econ. & Envir. Issues

Chapter 1,2

3,4,5 6,7 8,9 10 11

12,13 14,15,16

17,18

20,21 22

Lectures: will highlight important portions of each chapter. Chapter 1 - 10

Course Objectives Structure • Understand covalent, metallic and ionic primary bonding; understand the nature and role of secondary bonding. • Be able to describe the most important crystal structures by their unit cells. Be able to specify planes and directions by their indices. Execute density calculations. Understand polymorphism and allotropy. Distinguish between single crystal and polycrystalline materials. • Distinguish between isotropy and anisotropy, and homogeneity and inhomogeneity in materials. • Be able to describe semi-crystalline and non-crystalline structures. • Have the ability to describe important deviations from perfect crystalline structures: point, line, planar and volume defects. Understand their role in shaping material properties. Develop a qualitative understanding of the role of dislocations in the yielding of crystalline materials.

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Course Objectives (cont) Mechanical Behavior • Be able to use the concepts of stress and strain in one dimension. Understand the tensile test, and be able to derive relevant mechanical parameters from such a test. • Understand the stiffness parameters for Young’s modulus and shear modulus, as well as Poisson’s ratio, for small deformations. • Know how to derive yield points from tensile tests. Be able to describe test curves past the yield point. Understand elastic recovery in a yielded material. • Relate yield strength to number of slip systems in various crystalline structures and to resolved shear stresses. • Understand differences between compression and tensile tests. Be able to relate hardness values to yield stress. • Understand the variability (statistical nature) of many mechanical parameters.

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Course Objectives (cont) Dislocations and Strengthening Mechanisms for Crystalline Materials • Understand the concepts of dislocations and slip systems in the plastic deformation of crystalline material systems. • Know the basic principle of strengthening: hindering dislocation motion. • Understand the four basic methods of strengthening: formation of solid solutions, grain size refinement, formation of fine dispersions of a second phase, and cold working. • Be able to solve one dimensional steady state and non-steady state diffusion problems involved in thermal processing of metals. Understand the factors that influence diffusion. • Understand the processes of recovery, recrystallization and grain growth used to “undo” cold work.

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Course Objectives (cont) Failure • Know the principal modes of failure: brittle fracture, ductile fracture and creep. • Be able to describe brittle fracture. Be able to use the elementary parameters of fracture mechanics: stress concentrations, critical strain energy release rate, fracture toughness. Know impact test methods, and be able to interpret brittle to ductile transitions. • Be able to describe the generalized creep behavior of metals, including stress and temperature effects. Be able to apply temperature-time extrapolation methods

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Course Objectives (cont) Phase Diagrams • Be able to calculate all relevant quantities in binary equilibrium phase diagrams: number of phases, composition of phases, and phase amounts. Be able to identify the eutectic and eutectoid, as well as the peritectic and peritectoid reactions. • Be able to interpret the Gibb’s phase rule. • Be familiar with the equilibrium Fe-C phase diagram. Be able to explain the development of equilibrium microstructures in these alloys, and the role of additional elements on the development of these microstructures. • Understand the influence of other alloying elements on the binary phase diagram.

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Course Objectives (cont) Metal Alloys, Ceramics and Polymer •  Understand the basic material structure, including the role of

structural features on properties. •  Be able to describe and interpret the mechanical behavior and

properties of metal alloys, ceramics and polymers. Understand the role of temperature and composition on mechanical behavior.

•  Be familiar with applications and processing approaches for basic metal alloys, ceramics and polymer systems.

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Course Objectives (cont) Additional Topics (to be addressed with time permitting) • Material properties – chemical, electrical, mechanical, physical • Composites – structure, types, purpose, mixing laws • Corrosion mechanisms and control • Surface conditions – corrosion, degradation, coatings, finishes

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Chapter 1 - Introduction

•  What is materials science? •  Why should we know about it?

•  Materials drive our society –  Stone Age –  Bronze Age –  Iron Age –  Now?

•  Silicon Age? •  Polymer Age?

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Example – Hip Implant •  With age or certain illnesses joints deteriorate.

Particularly those with large loads (such as hip).

Adapted from Fig. 22.25, Callister 7e.

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Example – Hip Implant

•  Requirements – mechanical

strength (many cycles)

– good lubricity – biocompatibility

Adapted from Fig. 22.24, Callister 7e.

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Example – Hip Implant

Adapted from Fig. 22.26, Callister 7e.

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Hip Implant •  Key problems to overcome

–  fixation agent to hold acetabular cup

–  cup lubrication material –  femoral stem – fixing agent

(“glue”) –  must avoid any debris in cup

Adapted from chapter-opening photograph, Chapter 22, Callister 7e.

Femoral Stem

Ball

Acetabular Cup and Liner

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Example – Develop New Types of Polymers

•  Commodity plastics – large volume ca. $0.50 / lb Ex. Polyethylene Polypropylene Polystyrene etc.

•  Engineering Resins – small volume > $1.00 / lb

Ex. Polycarbonate Nylon Polysulfone etc.

Can polypropylene be “upgraded” to properties (and price) near those of engineering resins?

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ex: hardness vs structure of steel • Properties depend on structure

Data obtained from Figs. 10.30(a) and 10.32 with 4 wt% C composition, and from Fig. 11.14 and associated discussion, Callister 7e. Micrographs adapted from (a) Fig. 10.19; (b) Fig. 9.30;(c) Fig. 10.33; and (d) Fig. 10.21, Callister 7e.

ex: structure vs cooling rate of steel • Processing can change structure

Structure, Processing, & Properties

Har

dnes

s (B

HN

)

Cooling Rate (ºC/s)

100 2 00 3 00 4 00 5 00 6 00

0.01 0.1 1 10 100 1000

(d)

30 µm (c)

4 µm (b)

30 µm

(a)

30 µm

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Types of Materials •  Metals:

–  Strong, ductile –  high thermal & electrical conductivity –  opaque, reflective.

•  Polymers/plastics: Covalent bonding à sharing of e’s –  Soft, ductile, low strength, low density –  thermal & electrical insulators –  Optically translucent or transparent.

•  Ceramics: ionic bonding (refractory) – compounds of metallic & non-metallic elements (oxides, carbides, nitrides, sulfides) –  Brittle, glassy, elastic –  non-conducting (insulators)

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Types of Materials

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Properties of Materials •  Mechanical •  Electrical •  Thermal •  Magnetic •  Optical •  Deteriorative

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1. Pick Application Determine required Properties

2. Properties Identify candidate Material(s)

3. Material Identify required Processing Processing: changes structure and overall shape ex: casting, sintering, vapor deposition, doping forming, joining, annealing.

Properties: mechanical, electrical, thermal, magnetic, optical, deteriorative.

Material: structure, composition.

The Materials Selection Process

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ELECTRICAL • Electrical Resistivity of Copper:

• Adding “impurity” atoms to Cu increases resistivity. • Deforming Cu increases resistivity.

Adapted from Fig. 18.8, Callister 7e. (Fig. 18.8 adapted from: J.O. Linde, Ann Physik 5, 219 (1932); and C.A. Wert and R.M. Thomson, Physics of Solids, 2nd edition, McGraw-Hill Company, New York, 1970.)

T (°C) -200 -100 0

Cu + 3.32 at%Ni

Cu + 2.16 at%Ni

deformed Cu + 1.12 at%Ni

1

2

3

4

5

6

Res

istiv

ity, ρ

(1

0-8 O

hm-m

) 0

Cu + 1.12 at%Ni

“Pure” Cu

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THERMAL • Space Shuttle Tiles: --Silica fiber insulation offers low heat conduction.

• Thermal Conductivity of Copper: --It decreases when you add zinc!

Adapted from Fig. 19.4W, Callister 6e. (Courtesy of Lockheed Aerospace Ceramics Systems, Sunnyvale, CA) (Note: "W" denotes fig. is on CD-ROM.)

Adapted from Fig. 19.4, Callister 7e. (Fig. 19.4 is adapted from Metals Handbook: Properties and Selection: Nonferrous alloys and Pure Metals, Vol. 2, 9th ed., H. Baker, (Managing Editor), American Society for Metals, 1979, p. 315.)

Composition (wt% Zinc) Th

erm

al C

ondu

ctiv

ity

(W/m

-K)

400

300 200 100

0 0 10 20 30 40

100 µm

Adapted from chapter-opening photograph, Chapter 19, Callister 7e. (Courtesy of Lockheed Missiles and Space Company, Inc.)

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MAGNETIC • Magnetic Permeability vs. Composition: --Adding 3 atomic % Si makes Fe a better recording medium!

Adapted from C.R. Barrett, W.D. Nix, and A.S. Tetelman, The Principles of Engineering Materials, Fig. 1-7(a), p. 9, 1973.  Electronically reproduced by permission of Pearson Education, Inc., Upper Saddle River, New Jersey.

Fig. 20.23, Callister 7e. (Fig. 20.23 is from J.U. Lemke, MRS Bulletin, Vol. XV, No. 3, p. 31, 1990.)

• Magnetic Storage: --Recording medium is magnetized by recording head.

Magnetic Field

Mag

netiz

atio

n Fe+3%Si

Fe

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• Transmittance: --Aluminum oxide may be transparent, translucent, or opaque depending on the material structure.

Adapted from Fig. 1.2, Callister 7e. (Specimen preparation, P.A. Lessing; photo by S. Tanner.)

single crystal polycrystal: low porosity

polycrystal: high porosity

OPTICAL

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DETERIORATIVE • Stress & Saltwater... --causes cracks!

Adapted from chapter-opening photograph, Chapter 17, Callister 7e. (from Marine Corrosion, Causes, and Prevention, John Wiley and Sons, Inc., 1975.) 4 µm --material:

7150-T651 Al "alloy" (Zn,Cu,Mg,Zr)

Adapted from Fig. 11.26, Callister 7e. (Fig. 11.26 provided courtesy of G.H. Narayanan and A.G. Miller, Boeing Commercial Airplane Company.)

• Heat treatment: slows crack speed in salt water!

Adapted from Fig. 11.20(b), R.W. Hertzberg, "Deformation and Fracture Mechanics of Engineering Materials" (4th ed.), p. 505, John Wiley and Sons, 1996. (Original source: Markus O. Speidel, Brown Boveri Co.)

“held at 160ºC for 1 hr before testing”

increasing load crac

k sp

eed

(m/s

)

“as-is”

10 -10

10 -8

Alloy 7178 tested in saturated aqueous NaCl solution at 23ºC

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• Use the right material for the job.

• Understand the relation between properties, structure, and processing.

• Recognize new design opportunities offered by materials selection.

Course Goals: SUMMARY

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Reading: Chapters 1 and 2/1-19-11

ASSIGNMENT/DUE DATE