CHAPTER 1

I. Terminologies

Materials Scienceinvestigating the relationships that existbetween the structures and properties of materials.

Materials Engineeringdesigning or engineeringthe structure of a material to produce a predetermined set of properties

materials scientistdevelops or synthesizes new materials

materials engineercreate new products or systems using existing materials, and/or to develop techniques for processing materials

Structurerelates to the arrangement of its internalcomponents

microscopicthat which is subject to direct observationusing some type of microscope.

macroscopicthat may be viewed withthe naked eye are termed “.

Propertya material trait in terms of the kind and magnitudeof response to a specific imposed stimulus

Metalscomposed of one or more metallic elements and often also nonmetallic elements in relatively small amounts. Atoms in metals and their alloys are arranged in a very orderly manner and in comparison to the ceramics and polymers, are relatively dense. These materials are relatively stiff and strong, yet are ductile and are resistant to fracture. Metallic materials have large numbers of nonlocalized electrons; that is, these electrons are not bound to particular atoms.properties of metals are directly attributable to these electrons:extremely good conductors of electricity and heatnot transparent to visible lighta polished metal surface has a lustrous appearanceIn addition, some of the metals (viz., Fe, Co, and Ni) have desirable magnetic properties.

CeramicsCeramics are compounds between metallic and nonmetallic elements; they are mostfrequently oxides, nitrides, and carbides.Characteristics:are relatively stiff and strong—stiffnesses and strengths are comparable to those of the metals

typically very hard. On the other hand, they are extremely brittle (lack ductility), and are highly susceptible to fracturetypically insulative to the passage of heat and electricity, and are more resistant to high temperatures and harsh environments than metals and polymersoptical characteristics, ceramics may be transparent, translucent, or opaque and some of the oxide ceramics (e.g., Fe3O4) exhibit magnetic behavior.

PolymersPolymers include the familiar plastic and rubber materials. Many of them are organiccompounds that are chemically based on carbon, hydrogen, and other nonmetallicelementshave very large molecular structures,often chain-like in nature that have a backbone of carbon atomstypically have low densities, whereas their mechanical characteristicsare generally dissimilar to the metallic and ceramic materials—they are not as stiffnor as strong as these other material typeseasily formed into complex shapes

Drawbacks:tendency to soften and/or decompose at modest temperatures, which, in some instances,limits their use.low electrical conductivities and are nonmagnetic

CompositesA composite is composed of two (or more) individual materials, which come fromthe categories discussed above—viz., metals, ceramics, and polymers. The design goalof a composite is to achieve a combination of properties that is not displayed byany single material, and also to incorporate the best characteristics of each of thecomponent materials.

Advanced MaterialsMaterials that are utilized in high-technology (or high-tech) applications are sometimestermed.typically traditional materials whose properties have been enhanced,and, also newly developed, high-performance materials. Furthermore, they may beof all material types (e.g., metals, ceramics, polymers), and are normally expensive

High Technology we mean a device or productthat operates or functions using relatively intricate and sophisticated principles; examplesinclude electronic equipment (camcorders, CD/DVD players, etc.), computers,fiber-optic systems, spacecraft, aircraft, and military rocketry.

SemiconductorsSemiconductors have electrical properties that are intermediate between the electricalconductors (viz. metals and metal alloys) and insulator

BiomaterialsBiomaterials are employed in components implanted into the human body forreplacement of diseased or damaged body parts.These materials must not producetoxic substances and must be compatible with body tissues

Smart MaterialsSmart (or intelligent) materials are a group of new and state-of-the-art materialsnow being developed that will have a significant influence on many of our technologies“smart” implies that these materials are able to sense changesin their environments and then respond to these changes in predetermined manners—traits that are also found in living organisms

sensor detects an input signal

actuator performs a responsive and adaptive functionmay be called upon to change shape, position, naturalfrequency, or mechanical characteristics in response to changes in temperature,electric fields, and/or magnetic fields

Shape memoryalloys are metals that, after having been deformed,revert back to their original shapes when temperature is changed

Piezoelectric ceramicsexpand and contract in response to an applied electric field (or voltage) also generate an electric field when their dimensions are altered

magnetostrictive materialsits behavior is analogous to that of the piezoelectrics, except that they are responsive to magnetic fields. electrorheological and magnetorheological fluidsliquids that experience dramatic changes in viscosity uponthe application of electric and magnetic fields, respectively.

Nanoengineered Materialsmaterials that are built from simple atomic-level constituents

NanotechnologyBranch of technology that deals with dimensions and tolerances of less than 100 nanometers, especially the manipulation of individual atoms and molecules

Topdown scienceApproach that begins with studying large and complex structures then investigating the fundamental building blocks structures which are smaller and simpler.

bottom-up approachmanipulation and moving of atoms and molecules to form new structuresand with that, design new materials that are built from simple atomic-level constituents. With this kind of ability to carefully arrange atoms, opportunities open in the development of mechanical, electrical, magnetic, and other properties that are not otherwise possible.

II. FormulasNo formulas yet.

III. Enumerative Data

important properties of solid materials may be grouped into six differentcategories:

mechanical electrical thermal magnetic optical deteriorative

Mechanical properties relate deformation to an applied load or force; examplesinclude elastic modulus and strength. For electrical properties, such as electricalconductivity and dielectric constant, the stimulus is an electric field. The thermal behaviorof solids can be represented in terms of heat capacity and thermal conductivity.Magnetic properties demonstrate the response of a material to the application ofa magnetic field. For optical properties, the stimulus is electromagnetic or light radiation;index of refraction and reflectivity are representative optical properties. Finally,deteriorative characteristics relate to the chemical reactivity of materials

four components of the discipline of materials science andengineering and their interrelationship

processing structure properties performance

3 important criteria in-service conditions any deterioration of material properties that may occur during service operation finished product cost

three basic classifications of solids (based primarily on chemical makeup andatomic structure,)

metals ceramics polymers

advanced materials Semiconductors Biomaterials Materials of the Future

Materials of the future Smart Materials

Nanoengineered Materials

Components of a smart material (or system) sensor actuator

Four types of materials are commonly used for actuators shape memory alloys piezoelectric ceramics magnetostrictive materials electrorheological/magnetorheologicalfluids.

Materials/devices employed as sensors optical fibers piezoelectric materials (including some polymers) microelectromechanical devices