Introduction to Material Science

Materials Science and Engineering The discipline of investigating the relationships that exist between the structures and properties of materials. Materials Engineering The discipline of designing or engineering the structure of a material to produce a predetermined set of properties based on established structure-property correlation. Four Major Components of Material Science and Engineering: Structure of Materials Properties of Materials Processing of Materials Performance of Materials

And Remember: Materials “Drive” our Society! Ages of “Man” we survive based on the materials we control Stone Age – naturally occurring materials Special rocks, skins, wood Bronze Age Casting and forging Iron Age High Temperature furnaces Steel Age High Strength Alloys Non-Ferrous and Polymer Age Aluminum, Titanium and Nickel (superalloys) – aerospace Silicon – Information Plastics and Composites – food preservation, housing, aerospace and higher speeds Exotic Materials Age? Nano-Material and bio-Materials – they are coming and then …

Doing Materials! Engineered Materials are a function of: Raw Materials Elemental Control Processing History Our Role in Engineering Materials then is to understand the application and specify the appropriate material to do the job as a function of: Strength: yield and ultimate Ductility, flexibility Weight/density Working Environment Cost: Lifecycle expenses, Environmental impact* * Economic and Environmental Factors often are the most important when making the final decision!

Example of Materials Engineering Work – Hip Implant With age or certain illnesses joints deteriorate. Particularly those with large loads (such as hip). Adapted from Fig. 22.25, Callister 7e.

Example – Hip Implant Requirements mechanical strength (many cycles) good lubricity biocompatibility Adapted from Fig. 22.24, Callister 7e.

Example – Hip Implant Adapted from Fig. 22.24, Callister 7e.

Solution – Hip Implant Key Problems to overcome: Acetabular Cup and Liner Key Problems to overcome: fixation agent to hold acetabular cup cup lubrication material femoral stem – fixing agent (“glue”) must avoid any debris in cup Must hold up in body chemistry Must be strong yet flexible Ball Femoral Stem

Types of Materials Major Types of Materials Other Materials METALS CERAMICS POLYMERS Other Materials COMPOSITES ELECTRONIC MATERIALS ADVANCED MATERIALS

Materials Metals Ceramics Polymers Composites Steel, Cast Iron, Aluminum, Copper, Titanium, many others Ceramics Glass, Concrete, Brick, Alumina, Zirconia, SiN, SiC Polymers Plastics, Wood, Cotton (rayon, nylon), “glue” Composites Glass Fiber-reinforced polymers, Carbon Fiber-reinforced polymers, Metal Matrix Composites, etc.

Metals Ceramics Some of these have descriptive subclasses. Classes have overlap, so some materials fit into more than one class. Metals Iron and Steel Alloys and Superalloys (e.g. aerospace applications)  Intermetallic Compounds (high-T structural materials) Ceramics Structural Ceramics (high-temperature load bearing) Refractories (corrosion-resistant, insulating) Whitewares (e.g. porcelains) Glass Electrical Ceramics (capacitors, insulators, transducers, etc.)  Chemically Bonded Ceramics (e.g. cement and concrete)

Biomaterials (really using previous 5, but bio-mimetic) Polymers  Plastics Liquid crystals Adhesives Composites Particulate composites (small particles embedded in a different material) Laminate composites (golf club shafts, tennis rackets, Damaskus swords) Fiber reinforced composites (e.g. fiberglass) Electronic Materials Silicon and Germanium III-V Compounds (e.g. GaAs) Photonic materials (solid-state lasers, LEDs) Biomaterials (really using previous 5, but bio-mimetic) Man-made proteins (cytoskeletal protein rods or “artificial bacterium”) Biosensors (Au-nanoparticles stabilized by encoded DNA for anthrax detection) Drug-delivery colloids (polymer based)

Thoughts about these “fundamental” Materials Metals: 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, elastic non-conducting (insulators) Metals have high thermal & electrical conductivity because valence electrons are free to roam

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.

ASHBY “Strength-Density” Material Selection Diagram

Detailed diagram for Metals Detailed diagram for ceramics

ASHBY “Strength-Ductility” Material Selection Diagram

ASHBY “Strength-Cost” Material Selection Diagram

Processing can change structure! (see above structure vs Cooling Rate) Properties of Materials (ex: Strength or Hardness, etc.) Depend on Structure (d) 30 mm 6 00 Example: 1080 Steel 5 00 (c) 4 mm 4 00 (b) 30 mm (a) 30 mm Hardness (BHN) 3 00 2 00 100 0.01 0.1 1 10 100 1000 Cooling Rate (ºC/s) And: Processing can change structure! (see above structure vs Cooling Rate)

Another Example: Rolling of Steel At h1, L1 low UTS low YS high ductility round grains At h2, L2 high UTS high YS low ductility elongated grains Structure determines Properties but Processing determines Structure!

Optical Properties of Ceramic are controlled by “Grain Structure” Grain Structure is a function of “Solidification” processing!

Electrical Properties (of Copper): T (°C) -200 -100 Cu + 3.32 at%Ni Cu + 2.16 at%Ni deformed Cu + 1.12 at%Ni 1 2 3 4 5 6 Resistivity, r (10-8 Ohm-m) Cu + 1.12 at%Ni “Pure” Cu Electrical Resistivity of Copper is affected by: Contaminate level Degree of deformation Operating temperature 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.)

THERMAL Properties • Space Shuttle Tiles: • Thermal Conductivity --Silica fiber insulation offers low heat conduction. • Thermal Conductivity of Copper: --It decreases when you add zinc! Composition (wt% Zinc) Thermal Conductivity (W/m-K) 400 300 200 100 10 20 30 40 100 mm 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.)

MAGNETIC Properties • Magnetic Permeability vs. Composition: --Adding 3 atomic % Si makes Fe a better recording medium! • Magnetic Storage: --Recording medium is magnetized by recording head. Magnetic Field Magnetization Fe+3%Si Fe Adapted from C.R. Barrett, W.D. Nix, and A.S. Tetelman, The Principles of Engineering Materials, Fig. 1-7(a), p. 9, 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.)

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

Courses on Materials Science will make you aware of the importance of Material Selection by: • Using the right material for the job. one that is most economical and “Greenest” when life usage is considered • Understanding the relation between properties, structure, and processing. • Recognizing new design opportunities offered by materials selection.