Material Science Introduction

What are Materials? That’s easy! Look around. Our clothes are made of materials, our homes are made of materials - mostly manufactured. Glass windows, vinyl siding, metal silverware, ceramic dishes… Most things are made from many different kinds of materials.

Materials Science and Engineering It all about the raw materials and how they are processed That is why we call it materials ENGINEERING Minor differences in Raw materials or processing parameters can mean major changes in the performance of the final material or product

Materials Science and Engineering An interdisciplinary study that combines metallurgy, physics, chemistry, and engineering to solve real-world problems with real-world materials in an acceptable societal and economical manner. (VCSU, 2006)

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

Materials Science - Example The dramatic role of iron throughout the ages is not really the result of it being "strong". In reality, iron has been important because we can change its properties by heating and cooling it. The ability to change the properties and/or behavior of a material is what makes most materials useful and this is at the heart of materials science! (MSECRC, 2006)

History of Materials Man has been studying materials since before leaving the cave. Due to lack of communication, early man spent hundreds of millennia experimenting with stone tools. The first metal tools appeared perhaps only six thousand years ago.

History of Materials The discovery of “Iceman” in the Alps in 1991 gave significant information on early Copper age. He was carrying a copper axe. It is dated at about 5300 years, when the first pyramids were built.

History of Materials As our knowledge of materials grows, so does the sophistication of our tools. The more sophisticated our tools, the more sophisticated our accomplishments.

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

Introduction List the Major Types of MATERIALS That You Know: METALS CERAMICS POLYMERS SEMICONDUCTORS COMPOSITES ADVANCED MATERIALS

Kinds of Materials Metals: are materials that are normally combinations of "metallic elements". Metals usually are good conductors of heat and electricity. Also, they are quite strong but malleable and tend to have a lustrous look when polished. Ceramics: are generally compounds between metallic and nonmetallic elements. Typically they are insulating and resistant to high temperatures and harsh environments. (MSECRC, 2006)

Several uses of steel and pressed aluminum. Metals Several uses of steel and pressed aluminum.

Ceramics Examples of ceramic materials ranging from household to high performance combustion engines which utilize both metals and ceramics.

Kinds of Materials Polymers: (or plastics) are generally organic compounds based upon carbon and hydrogen. They are very large molecular structures. Usually they are low density and are not stable at high temperatures. Semiconductors: have electrical properties intermediate between metallic conductors and ceramic insulators. Also, the electrical properties are strongly dependent upon small amounts of impurities. (MSECRC, 2006)

Polymers include “Plastics” and rubber materials

Semiconductors Micro-Electrical-Mechanical Systems (MEMS) Si wafer for computer chip devices.

Kinds of Materials Composites: consist of more than one material type. Fiberglass, a combination of glass and a polymer, is an example. Concrete and plywood are other familiar composites. Many new combinations include ceramic fibers in metal or polymer matrix. (MSECRC, 2006)

Composites Polymer composite materials: reinforcing glass fibers in a polymer matrix.

Newer Branches of Materials Science Nanotechnology: a relatively new area grown out of techniques used to manufacture semiconductor circuits. Machines can be produced on a microscopic level. Example - miniature robots to do surgery inside the body or miniature chemical laboratories and instruments that will continuously analyze blood and dispense medications inside the body. (VCSU, 2006)

NanoTech As Hygienic as a Shark? Yes, they avoid pesky algae and bacteria by way of an ingenious skin design. Microorganisms prefer flat surfaces, which allow them to form large colonies or biofilms. But unlike most other fish, sharks don't have flat scales. Instead, they have dermal denticles—ridged, tooth-like scales covering their body (pictured here). These bumpy "teeth" create a rough surface that biofilms can't colonize or thrive on, which contributes to the shark's naturally bacteria-free status. In the not too distant future, dozens of intriguing nanodevices such as the nanotubes above may transform cancer diagnosis, treatment, and prevention.

Introduction, cont. 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.

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, doping, annealing.

Processing can change structure! (see above structure vs Cooling Rate) But: Properties depend on Structure (strength or hardness) (d) 30 mm 6 00 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 tensile strength low yield strength high ductility round grains At h2, L2 high tensile strength high yield strength 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.)

Goal is to 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.

Future of Material Science Design of materials having specific desired characteristics directly from our knowledge of atomic structure. Miniaturization: “Nanostructured" materials, with microstructure that has length scales between 1 and 100 nanometers with unusual properties. Electronic components, materials for quantum computing. Smart materials: airplane wings that deice or move themselves, buildings that stabilize themselves in earthquakes…

Future of Material Science Environment-friendly materials: biodegradable or photodegradable plastics, advances in nuclear waste processing, etc. Learning from Nature: shells and biological hard tissue can be as strong as the most advanced laboratory-produced ceramics, mollusks produce biocompatible adhesives that we do not know how to reproduce… Materials for lightweight batteries with high storage densities, for turbine blades that can operate at 2500°C, room-temperature superconductors? chemical sensors (artificial nose) of extremely high sensitivity, cotton shirts that never require ironing…