ME 201 Engineering Materials Course Objective Introduce fundamental
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 Chapter 1 - 1
LECTURES Instructor: Dr. Mehr Nigar Grading Policy: • Quizzes & Assignments* • Mid-Term Exam* • End-Semester Exam 15 -20% 25 -30% 50 -55% *No Make-ups under any circumstances. *Discuss potential conflicts beforehand. Chapter 1 - 2
COURSE MATERIALS Required text: • Materials Science and Engineering: An Introduction W. D. Callister, Jr. , 7 th edition, John Wiley and Sons, Inc. (2007). ( or latest edition) Chapter 1 - 3
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 Chapter 1 - 4
CHAPTER 1 Chapter 1 - 6
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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? Chapter 1 - 8
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• The Iron Pillar from Delhi (built in the late 4 th or early 5 th 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 Chapter 1 - 10
Example – Hip Implant Adapted from Fig. 22. 26, Callister 7 e. Chapter 1 - 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) Chapter 1 - 13
Types of Materials Chapter 1 - 14
Densities of Various Materials Chapter 1 - 15
Structure, Processing, & Properties • Properties depend on structure ex: hardness vs structure of steel (d) Hardness (BHN) 600 500 400 (c) (a) (b) 4 mm 300 200 30 mm 100 0. 01 0. 1 30 mm Data obtained from Figs. 10. 30(a) and 10. 32 with 4 wt% C composition, and from Fig. 11. 14 and associated discussion, Callister 7 e. Micrographs adapted from (a) Fig. 10. 19; (b) Fig. 9. 30; (c) Fig. 10. 33; and (d) Fig. 10. 21, Callister 7 e. 1 10 1000 Cooling Rate (ºC/s) • Processing can change structure ex: structure vs cooling rate of steel Chapter 1 - 16
ELECTRICAL • Electrical Resistivity of Copper: 6 (10 -8 Ohm-m) Resistivity, r 5 4 3 2 1 0 Ni Cu + t% a 2 3. 3 Ni % t Ni 16 a. % t 2 a + 2 1. Cu +1 u C d e rm Ni % t defo 12 a. 1 + Cu Cu ” e r “Pu -200 -100 0 Adapted from Fig. 18. 8, Callister 7 e. (Fig. 18. 8 adapted from: J. O. Linde, Ann Physik 5, 219 (1932); and C. A. Wert and R. M. Thomson, Physics of Solids, 2 nd edition, Mc. Graw-Hill Company, New York, 1970. ) T (°C) • Adding “impurity” atoms to Cu increases resistivity. • Deforming Cu increases resistivity. Chapter 1 - 17
OPTICAL • Transmittance: --Aluminum oxide may be transparent, translucent, or opaque depending on the material structure. single crystal polycrystal: low porosity polycrystal: high porosity Adapted from Fig. 1. 2, Callister 7 e. (Specimen preparation, P. A. Lessing; photo by S. Tanner. ) Chapter 1 - 18
DETERIORATIVE • Stress & Saltwater. . . crack speed in salt water! crack speed (m/s) --causes cracks! • Heat treatment: slows 10 -8 10 -10 Adapted from chapter-opening photograph, Chapter 17, Callister 7 e. (from Marine Corrosion, Causes, and Prevention, John Wiley and Sons, Inc. , 1975. ) “as-is” “held at 160ºC for 1 hr before testing” Alloy 7178 tested in saturated aqueous Na. Cl solution at 23ºC increasing load Adapted from Fig. 11. 20(b), R. W. Hertzberg, "Deformation and Fracture Mechanics of Engineering Materials" (4 th ed. ), p. 505, John Wiley and Sons, 1996. (Original source: Markus O. Speidel, Brown Boveri Co. ) --material: 4 mm 7150 -T 651 Al "alloy" (Zn, Cu, Mg, Zr) Adapted from Fig. 11. 26, Callister 7 e. (Fig. 11. 26 provided courtesy of G. H. Narayanan and A. G. Miller, Boeing Commercial Chapter 1 - 19 Airplane Company. )
The Materials Selection Process 1. Pick Application Determine required Properties: mechanical, electrical, thermal, magnetic, optical, deteriorative. 2. Properties Identify candidate Material(s) Material: structure, composition. 3. Material Identify required Processing: changes structure and overall shape ex: casting, sintering, vapor deposition, doping forming, joining, annealing. Chapter 1 - 20
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. Chapter 1 - 21
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 Chapter 1 - 22
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. Chapter 1 - 23
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