Foundations of Materials Science and Engineering Fourth Edition PowerPoint Lecture Slides for Foundations of Materials Science and Engineering Fourth Edition William F. Smith Javad Hashemi

Introduction to Materials Science and Engineering CHAPTER 1 Introduction to Materials Science and Engineering 1-1

The Mars Rovers - Spirit and Opportunity Spirit and Opportunity are made up of materials such as * Metals * Ceramics * Composites * Polymers * Semiconductors 1-2 www.nasa.gov

What are Materials? Examples :- Materials may be defined as substance of which something is composed or made. We obtain materials from earth crust and atmosphere. Examples :- Silicon and Iron constitute 27.72 and 5.00 percentage of weight of earths crust respectively. Nitrogen and Oxygen constitute 78.08 and 20.95 percentage of dry air by volume respectively. 1-3

Why the Study of Materials is Important? Production and processing of materials constitute a large part of our economy. Engineers choose materials to suite design. New materials might be needed for some new applications. Example :- High temperature resistant materials. Space station and Mars Rovers should sustain conditions in space. * High speed, low temperature, strong but light. Modification of properties might be needed for some applications. Example :- Heat treatment to modify properties. 1-4

Materials Science and Engineering Materials science deals with basic knowledge about the internal structure, properties and processing of materials. Materials engineering deals with the application of knowledge gained by materials science to convert materials to products. Materials Science and Engineering Materials Science Materials Engineering Basic Knowledge of Materials Applied Knowledge of Materials Resultant Knowledge of Structure and Properties 1-5

Types of Materials Metallic Materials Composed of one or more metallic elements. Example:- Iron, Copper, Aluminum. Metallic element may combine with nonmetallic elements. Example:- Silicon Carbide, Iron Oxide. Inorganic and have crystalline structure. Good thermal and electric conductors. Metals and Alloys Ferrous Eg: Steel, Cast Iron Nonferrous Eg:Copper Aluminum 1-6

Polymeric (Plastic) Materials Types of Materials Polymeric (Plastic) Materials Organic giant molecules and mostly noncrystalline. Some are mixtures of crystalline and noncrystalline regions. Poor conductors of electricity and hence used as insulators. Strength and ductility vary greatly. Low densities and decomposition temperatures. Examples :- Poly vinyl Chloride (PVC), Polyester. Applications :- Appliances, DVDs, Fabrics etc. 1-7

Types of Materials Ceramic Materials Metallic and nonmetallic elements are chemically bonded together. Inorganic but can be either crystalline, noncrystalline or mixture of both. High hardness, strength and wear resistance. Very good insulator. Hence used for furnace lining for heat treating and melting metals. Also used in space shuttle to insulate it during exit and reentry into atmosphere. Other applications : Abrasives, construction materials, utensils etc. Example:- Porcelain, Glass, Silicon nitride. 1-8

Types of Materials Composite Materials Mixture of two or more materials. Consists of a filler material and a binding material. Materials only bond, will not dissolve in each other. Mainly two types :- Fibrous: Fibers in a matrix Particulate: Particles in a matrix Matrix can be metals, ceramic or polymer Examples :- Fiber Glass ( Reinforcing material in a polyester or epoxy matrix) Concrete ( Gravels or steel rods reinforced in cement and sand) Applications:- Aircraft wings and engine, construction. 1-9

Types of Materials Electronic Materials Not Major by volume but very important. Silicon is a common electronic material. Its electrical characteristics are changed by adding impurities. Examples:- Silicon chips, transistors Applications :- Computers, Integrated Circuits, Satellites etc. 1-10

Competition Among Materials Materials compete with each other to exist in new market Over a period of time usage of different materials changes depending on cost and performance. New, cheaper or better materials replace the old materials when there is a breakthrough in technology Example:- Figure 1.14 Predictions and use of materials in US automobiles. 1-11 After J.G. Simon, Adv. Mat. & Proc., 133:63(1988) and new data

Future Trends Metallic Materials Production follows US economy closely. Alloys may be improved by better chemistry and process control. New aerospace alloys being constantly researched. Aim: To improve temperature and corrosion resistance. Example: Nickel based high temperature super alloys. New processing techniques are investigated. Aim: To improve product life and fatigue properties. Example: Isothermal forging, Powder metallurgy. Metals for biomedical applications 1-12

Polymeric (Plastic Materials) Future Trends Polymeric (Plastic Materials) Fastest growing basic material (9% per year). After 1995 growth rate decreased due to saturation. Different polymeric materials can be blend together to produce new plastic alloys. Search for new plastic continues. 1-13

Future Trends Ceramic Materials New family of engineering ceramics are produced last decade New materials and applications are constantly found. Now used in Auto and Biomedical applications. Processing of ceramics is expensive. Easily damaged as they are highly brittle. Better processing techniques and high-impact ceramics are to be found. 1-14

Future Trends Composite Materials Fiber reinforced plastics are primary products. On an average 3% annual growth from 1981 to 1987. Annual growth rate of 5% is predicted for new composites such as Fiberglass-Epoxy and Graphite-Epoxy combinations. Commercial aircrafts are expected to use more and more composite materials. 1-15

Future Trends Electronic Materials Use of electronic materials such as silicon increased rapidly from 1970. Electronic materials are expected to play vital role in “Factories of Future”. Use of computers and robots will increase resulting in extensive growth in use of electronic materials. Aluminum for interconnections in integrated circuits might be replaced by copper resulting in better conductivity. 1-16

Future Trends Smart Materials : Change their properties by sensing external stimulus. Shape memory alloys: Strained material reverts back to its original shape above a critical temperature. Used in heart valves and to expand arteries. Piezoelectric materials: Produce electric field when exposed to force and vice versa. Used in actuators and vibration reducers. 1-17

MEMS and Nanomaterials MEMS: Microelectromechanical systems. Miniature devices Micro-pumps, sensors Nanomaterials: Characteristic length < 100 nm Examples: ceramics powder and grain size < 100 nm Nanomaterials are harder and stronger than bulk materials. Have biocompatible characteristics ( as in Zirconia) Transistors and diodes are developed on a nanowire. 1-18

Case Study – Material Selection Problem: Select suitable material for bicycle frame and fork. Steel and alloys Wood Carbon fiber Reinforced plastic Aluminum alloys Ti and Mg alloys Low cost but Heavy. Less Corrosion resistance Light and strong. But Cannot be shaped Very light and strong. No corrosion. Very expensive Light, moderately Strong. Corrosion Resistance. expensive Slightly better Than Al alloys. But much expensive Cost important? Select steel Properties important? Select CFRP 1-19