ME 201: Engineering Materials

1. ME 201: Engineering Materials Course Objective... Introduce fundamental concepts in Materials Science You will learn about: • material types & structure • how structure dictates properties • how processing can change structure This course will help you to: • choose the right material for a particular application • realize new design opportunities

2. LECTURES Instructor: Dr. Mehr Nigar Grading Policy: • Quizzes & Assignments* 15-20% • Mid-Term Exam* 25-30% • End-Semester Exam 50-55% *No Make-ups under any circumstances. *Discuss potential conflicts beforehand.

3. COURSE MATERIALS Required text: • Materials Science and Engineering: An Introduction W.D. Callister, Jr., 7th edition, John Wiley and Sons, Inc. (2007). ( or latest edition)

4. COURSE WEBSITES Text Website: http://www.wiley.com/college/callister • Additional Chapters (Chapters 19-23) • Complete solutions to selected problems • Links to other web resources • Extended learning objectives • Self-assessment exercises

5. CHAPTER 1

7. Chapter 1 - Introduction • What is materials science? • Why should we know about it? • Materials drive our society • Stone Age (~ 2.5 million BC) • Bronze Age (~ 3500 BC) • Iron Age (~ 1000 BC) • Now? • Silicon Age? • Polymer Age?

9. The Iron Pillar from Delhi(built in the late 4th or early 5th century; some historians have dated it to as early as 912 B.C!) 7.3 m tall, with one meter below the ground; the diameter is 48 centimeters at the foot, tapering to 29 cm at the top, just below the base of the wonderfully crafted capital; it weighs approximately 6.5 tones, and was manufactured by forged welding

10. Example – Hip Implant Adapted from Fig. 22.26, Callister 7e.

11. Types of Materials • Metals: Metallic bonding  free electrons not attracted to any one particular nucleus • Strong, ductile • high thermal & electrical conductivity • opaque, reflective. • Polymers/plastics: Covalent bonding  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, capable of elastic deformation only • non-conducting (insulators)

12. Types of Materials

13. Densities of Various Materials

14. Structure, Processing, & Properties (d) 30mm (c) (b) (a) 4mm 30mm 30mm • Properties depend on structure ex: hardness vs structure of steel 6 00 5 00 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. 4 00 Hardness (BHN) 3 00 2 00 100 0.01 0.1 1 10 100 1000 Cooling Rate (ºC/s) • Processing can change structure ex: structure vs cooling rate of steel

15. 6 5 Cu + 3.32 at%Ni 4 Cu + 2.16 at%Ni Resistivity, r deformed Cu + 1.12 at%Ni 3 (10-8 Ohm-m) 2 Cu + 1.12 at%Ni 1 “Pure” Cu 0 -200 -100 0 T (°C) ELECTRICAL • Electrical Resistivity of Copper: Adapted from Fig. 18.8, Callister 7e. (Fig. 18.8 adapted from: J.O. Linde, Ann Physik5, 219 (1932); and C.A. Wert and R.M. Thomson, Physics of Solids, 2nd edition, McGraw-Hill Company, New York, 1970.) • Adding “impurity” atoms to Cu increases resistivity. • Deforming Cu increases resistivity.

16. OPTICAL • Transmittance: --Aluminum oxide may be transparent, translucent, or opaque depending on the material structure. polycrystal: low porosity polycrystal: high porosity single crystal Adapted from Fig. 1.2, Callister 7e. (Specimen preparation, P.A. Lessing; photo by S. Tanner.)

17. -8 10 “as-is” “held at 160ºC for 1 hr crack speed (m/s) before testing” -10 10 Alloy 7178 tested in saturated aqueous NaCl solution at 23ºC increasing load 4mm --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.) DETERIORATIVE • Stress & Saltwater... --causes cracks! • 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.) Adapted from chapter-opening photograph, Chapter 17, Callister 7e. (from Marine Corrosion, Causes, and Prevention, John Wiley and Sons, Inc., 1975.)

18. The Materials Selection Process 1. Pick Application Determine required Properties Properties: mechanical, electrical, thermal, magnetic, optical, deteriorative. 2. Properties Identify candidate Material(s) Material: structure, composition. 3. Material Identify required Processing Processing: changes structure and overall shape ex: casting, sintering, vapor deposition, doping forming, joining, annealing.

19. Selection Criteria for Beverage Container • provide a barrier to the passage of carbon dioxide, which is under pressure in the container; • be nontoxic, unreactive with the beverage, and, preferably be recyclable; • be relatively strong, and capable of surviving a drop from a height of several feet when containing the beverage; • be inexpensive and the cost to fabricate the final shape should be relatively low; • if optically transparent, retain its optical clarity; • capable of being produced having different colors and/or able to be adorned with decorative labels.

20. Aluminum alloy is relatively strong (but easily dented), is a very good barrier to the diffusion of carbon dioxide, is easily recycled, beverages are cooled rapidly, and labels may be painted onto its surface, however they are opaque and expensive to produce. Glass is impervious to the passage of carbon dioxide, is a relatively inexpensive material, may be recycled, but it cracks and fractures easily, and glass bottles are relatively heavy Plastic is relatively strong, may be made optically transparent ,is inexpensive and lightweight, and is recyclable, it is not as impervious to the passage of carbon dioxide as aluminum and glass

21. SUMMARY Course Goals: • Use the right material for the job. • Understand the relation between properties, structure, and processing. • Recognize new design opportunities offered by materials selection.