Page 30 - Materials Science and Engineering An Introduction

Learning Objectives
After studying this chapter, you should be able to do the following:
1. List six different property classifications of mate- 4. (a) List the three primary classifications
rials that determine their applicability. of solid materials, and then cite the
2. Cite the four components that are involved in distinctive chemical feature of each.
the design, production, and utilization of materi- (b) Note the four types of advanced materials
als, and briefly describe the interrelationships and, for each, its distinctive feature(s).
between these components. 5. (a) Briefly define smart material/system.
3. Cite three criteria that are important in the ma- (b) Briefly explain the concept of nanotechnol-
terials selection process. ogy as it applies to materials.

1.1 HISTORICAL PERSPECTIVE
Materials are probably more deep seated in our culture than most of us realize.
Transportation, housing, clothing, communication, recreation, and food production—
virtually every segment of our everyday lives is influenced to one degree or another
by materials. Historically, the development and advancement of societies have been
intimately tied to the members’ ability to produce and manipulate materials to fill their
needs. In fact, early civilizations have been designated by the level of their materials
development (Stone Age, Bronze Age, Iron Age). 1
The earliest humans had access to only a very limited number of materials, those that
occur naturally: stone, wood, clay, skins, and so on. With time, they discovered techniques
for producing materials that had properties superior to those of the natural ones; these
new materials included pottery and various metals. Furthermore, it was discovered that the
properties of a material could be altered by heat treatments and by the addition of other
substances. At this point, materials utilization was totally a selection process that involved
deciding from a given, rather limited set of materials, the one best suited for an application
by virtue of its characteristics. It was not until relatively recent times that scientists came to
understand the relationships between the structural elements of materials and their proper-
ties. This knowledge, acquired over approximately the past 100 years, has empowered them
to fashion, to a large degree, the characteristics of materials. Thus, tens of thousands of dif-
ferent materials have evolved with rather specialized characteristics that meet the needs of
our modern and complex society, including metals, plastics, glasses, and fibers.
The development of many technologies that make our existence so comfortable
has been intimately associated with the accessibility of suitable materials. An advance-
ment in the understanding of a material type is often the forerunner to the stepwise
progression of a technology. For example, automobiles would not have been possible
without the availability of inexpensive steel or some other comparable substitute. In the
contemporary era, sophisticated electronic devices rely on components that are made
from what are called semiconducting materials.

1.2 MATERIALS SCIENCE AND ENGINEERING
Sometimes it is useful to subdivide the discipline of materials science and engineering
into materials science and materials engineering subdisciplines. Strictly speaking, materi-
als science involves investigating the relationships that exist between the structures and

1 The approximate dates for the beginnings of the Stone, Bronze, and Iron ages are 2.5 million bc, 3500 bc, and
1000 bc, respectively.

2 •