Materials Science andENGINEERING

Engineering
Edition
Eighth
MATERIALS SCIENCE AND Eighth Edition

William D. Callister, Jr.

David G. Rethwisch

Introduction to Materials Science and Engineering

Lecture Notes:
Solomon B.
Addis Ababa University
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• Course Number: Meng 2121

• Course Title: Materials Science and Engineering I

•
• Credit hours: 3

• ECTS : 5

• Instructor: Solomon B.
• Office : 305

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Assessment
• 1st Midterm Exam 15%
• 2nd Midterm Exam 15%
• Final Exam 35-40%
• Home works/term paper 15%
• Quizzes 10% (*)
• Lab 10%
(*) five quizzes total value of 10%

Term Paper: Each student will write a 4-page term paper

on a topic of interest in materials. Term papers are due on
final exam date.

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Eighth Edition

Introduction to Materials Science and Engineering

CHAPTER

1 William D. Callister, Jr.

David G. Rethwisch

Lecture Notes:
Solomon B.
Addis Ababa University
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Learning Objectives
After studying this chapter you should be able to do the
following:
1. List six different property classifications of materials that
determine their applicability.
2. Cite the four components that are involved in the design,
production, and utilization of materials, and briefly describe the
interrelationships between these components.
3. Cite three criteria that are important in the materials selection
process.
4. (a) List the three primary classifications of solid materials, and
then cite the distinctive chemical feature of each.
(b) Note the four types of advanced materials and, for each, its
distinctive feature(s).
5. (a) Briefly define “smart material/system.”
(b) Briefly explain the concept of “nanotechnology” as it applies
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Why Materials Science and Engineered is

important for all ENGINEERS?
 Materials Science and Engineered is a broad,
multidisciplinary field of science devoted to
understanding and manipulating the different materials
properties including physical, mechanical, electrical,
optical and magnetic

 It studies fundamental characteristics of variety of

materials including metals, ceramics, polymers, and
composite materials.

 It is closely related to chemical and mechanical,

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Mechanical Engineering
 Mechanical engineering is among the most diversified of the
traditional engineering disciplines. Mechanical engineers design
and build machines and devices that enable humans to live and
work in space, in the air, on the ground, and under water.

 Naturally, much of what engineers can or cannot do depends on

the materials they have available to tackle their tasks. This is why
engineers and material scientists work closely together with the
goal of tailoring not only the mechanical, but also chemical and
electrical properties of materials to make new applications possible.

 You have to be able to talk with materials scientist on the same

professional language, formulate the problem and outline
routes for it solution.

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Mechanical Engineering

Polymers,
Metals,
Elastomers
Alloys
(Gears)
(Al-alloy)

Hybrids,
CFRP composites
Ceramics,
Glasses
(Plugs)

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Aerospace Engineering
 AeroEng. goals for subsonic, supersonic and hypersonic flight and for space
exploration call for alloys and composites notable for strength, light weight
and resistance to heat.
 The extraordinary diversity of todays advanced materials is based on better
knowledge of how to attain novel structures displaying new properties that lead
to improved performance.

Polymers,
elastomers
Metals,
alloys

Ceramics, Hybrids,
glasses composites

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Civil Engineering
• Civil engineering is a discipline that deals with the design, construction, and
maintenance of the physical and naturally built environment, including bridges,
canals, dams, and buildings.
• Materials science is closely related to civil engineering. Material engineering
studies fundamental characteristics of materials, and deals with ceramics such as
concrete and mix asphalt concrete, strong metals such as aluminum and steel,
and polymers and carbon fibers.

Metals,
alloys Polymers,
elastomers

Ceramics, Hybrids,
glasses composites

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Bio-engineering
• A biomaterial is any matter, surface, or construct that interacts with biological
systems.
• Biomaterials science encompasses elements of medicine, biology, chemistry,
tissue engineering and material science.

Polymers,
Metals, elastomers
alloys

Hybrids,
composites
Ceramics,
glasses

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Bio-engineering
• Example: Hip Implant

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Bio-engineering
• Example: Hip Implant

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

• Beginning of the Material Science –
• People began to make tools from stone – Start of the Stone Age
about two million years ago.
Natural materials: stone, wood, clay, skins, etc.
• The Stone Age ended about 5000 years ago with introduction of
Bronze in the Far East.
• Bronze is an alloy (a metal made up of more than one element),
copper + < 25% of tin + other elements.
• Bronze: can be hammered or cast into a variety of shapes, can
be made harder by alloying, corrode only slowly after a surface
oxide film forms.
• The Iron Age began about 3000 years ago and continues today.
Use of iron and steel, a stronger and cheaper material changed
drastically daily life of a common person.
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Historical Perspective
• Age of Advanced materials:
– throughout the Iron Age many new types of materials have been
introduced (ceramic, semiconductors, polymers, composites…).

– Understanding of the relationship among structure,

properties, processing, and performance of materials.
Intelligent design of new materials.

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What is Materials Science and Engineering?

• Materials science and engineering (MSE): is an interdisciplinary field of science
and engineering that studies and manipulates the composition and structure of
materials across length scales to control materials properties through synthesis
and processing.
– Composition: is the chemical make-up of a material.
– Structure: means a description of the arrangement of atoms, as seen at
different levels of detail
• The term “synthesis” refers to how materials are made from naturally occurring or
man-made chemicals
• The term “processing” means how materials are shaped into useful components to
cause changes in the properties of different materials.

• One of the most important functions of materials scientists and engineers is to

establish the relationships between a material or a device’s properties and
performance and the microstructure of that material, its composition, and the
way the material or the device was synthesized and processed
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What is Materials Science and Engineering?

Materials Science
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.

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materials science and engineering tetrahedron

• Let’s examine one example using the materials science and
engineering tetrahedron
Let’s look at “sheet steels” used in the manufacture of car chassis.
• In the manufacture of automobile chassis,
– A material is needed that possesses extremely high strength but is formed
easily into aerodynamic contours.
– It has to be fuel efficient, (so the sheet steel must also be thin and
lightweight.)
– The sheet steels also should be able to absorb significant amounts of
energy in the event of a crash, thereby increasing vehicle safety.
• These are somewhat contradictory requirements.
• Thus, in this case, materials scientists are concerned with the sheet
steel’s
– composition; strength; weight; energy absorption properties; and
– malleability (formability).
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What is Materials Science and Engineering?

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materials science and engineering tetrahedron

Let’s look at one more example of a class of materials known as semiconducting
polymers
• Many semiconducting polymers have been processed into light emitting diodes
(LEDs)
• These displays often use inorganic compounds based on gallium arsenide (GaAs)
and other materials. The advantage of using plastics for microelectronics is that
they are lightweight and flexible.
• The questions materials scientists and engineers must answer with applications of
semiconducting polymers are
– What are the relationships between the structure of polymers and their electrical
properties?
– How can devices be made using these plastics?
– Will these devices be compatible with existing silicon chip technology?
– How robust are these devices?
– How will the performance and cost of these devices compare with traditional devices?
• These are just a few of the factors that engineers and scientists must consider
during the development, design, and manufacture of semiconducting polymer
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materials science and engineering tetrahedron

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Properties
Properties are the way the material responds to the environment and
external forces.

Mechanical properties – response to mechanical forces, strength, etc.

Electrical and magnetic properties - response electrical and magnetic
fields, conductivity, etc.
Thermal properties are related to transmission of heat and heat
capacity.
Optical properties include to absorption, transmission and scattering of
light.
Chemical stability in contact with the environment - corrosion
resistance.

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Mechanical property
Materials in each of these groups possess different structures and properties.
• Since metallic materials are extensively used for load-bearing applications,
their mechanical properties are of great practical interest.
• The term “stress” refers to load or force per unit area. “Strain” refers to
elongation or change in dimension divided by the original dimension.
• Application of “stress” causes “strain.”
• If the strain goes away after the load or applied stress is removed, the strain is
said to be “elastic.”
• If the strain remains after the stress is removed, the strain is said to be “plastic.”
• When the deformation is elastic, stress and strain are linearly related; the slope
of the stress-strain diagram is known as the elastic or Young’s modulus.
• The level of stress needed to initiate plastic deformation is known as the “yield
strength.”
• The maximum percent deformation that can be achieved is a measure of the
ductility of a metallic material.

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Representative strengths of various categories of materials

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Classification of Materials
There are different ways of classifying materials. Let us classify materials
according to the way the atoms are bound together (Chapter 2).
• Metals: valence electrons are detached from atoms, and spread in an 'electron
sea' that "glues" the ions together. Strong, ductile, conduct electricity and heat
well, are shiny if polished.

• Semiconductors: the bonding is covalent (electrons are shared between atoms).

Their electrical properties depend strongly on minute proportions of
contaminants. Examples: Si, Ge, GaAs.

• Ceramics: atoms behave like either positive or negative ions, and are bound by
Coulomb forces. They are usually combinations of metals or semiconductors
with oxygen, nitrogen or carbon (oxides, nitrides, and carbides). Hard, brittle,
insulators. Examples: glass, porcelain.

• Polymers: are bound by covalent forces and also by weak van der Waals forces,
and usually based on C and H. They decompose at moderate temperatures (100 –
400 C), and are lightweight. Examples: plastics rubber.
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Functional Classification of Materials

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Functional Classification of Materials con…

• Aerospace
– Light materials such as wood and an aluminum alloy (that accidentally
strengthened the engine even more by picking up copper from the mold used
for casting) were used in the Wright brothers’ historic flight.
– Today, NASA’s space shuttle makes use of aluminum powder for booster
rockets. Aluminum alloys, plastics, silica for space shuttle tiles, and many
other materials belong to this category.

• Biomedical
– A number of artificial organs, bone replacement parts, cardiovascular stents,
orthodontic braces, and other components are made using different plastics,
titanium alloys, and nonmagnetic stainless steels.
– Ultrasonic imaging systems make use of ceramics known as PZT (lead
zirconium titanate).
– Magnets used for magnetic resonance imaging make use of metallic niobium
tin-based superconductors.
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Functional Classification of Materials con…

• Energy Technology and Environmental Technology
– The nuclear industry uses materials such as uranium dioxide and plutonium as
fuel. Numerous other materials, such as glasses and stainless steels, are used in
handling nuclear materials and managing radioactive waste.
– New technologies related to batteries and fuel cells make use of many ceramic
materials such as zirconia (ZrO2) and polymers.

• Magnetic Materials
– Computer hard disks make use of many ceramic, metallic, and polymeric
materials.
– Computer hard disks are made using alloys based on cobalt-platinum-
tantalum-chromium (Co-Pt-Ta-Cr) alloys.
– Many magnetic ferrites are used to make inductors and components for
wireless communications. Steels based on iron and silicon are used to make
transformer cores.
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Functional Classification of Materials con…

• Electronic Materials
– Semiconductors, such as those made from silicon, are used to make integrated
circuits for computer chips.
– Barium titanate (BaTiO3), tantalum oxide (Ta2O5), and many other dielectric
materials are used to make ceramic capacitors and other devices.

• Photonic or Optical Materials

– Silica is used widely for making optical fibers. More than ten million
kilometers of optical fiber have been installed around the world. Optical
materials are used for making semiconductor detectors and lasers used in fiber-
optic communications systems and other applications.
– Similarly, alumina (Al2O3) and yttrium aluminum garnets (YAG) are used for
making lasers.
– Amorphous silicon is used to make solar cells and photovoltaic modules.
– Polymers are used to make liquid crystal displays (LCDs).
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Functional Classification of Materials con…

• Smart Materials
– A smart material can sense and respond to an external stimulus such as a
change in temperature, the application of a stress, or a change in humidity or
chemical environment.
– Usually a smart material-based system consists of sensors and actuators that
read changes and initiate an action. An example of a passively smart material
is lead zirconium titanate (PZT) and shape-memory alloys. When properly
processed, PZT can be subjected to a stress, and a voltage is generated. This
effect is used to make such devices as sensors that can detect underwater
objects such as fish and submarines.
• Structural Materials
– These materials are designed for carrying some type of stress. Steels, concrete,
and composites are used to make buildings and bridges.
– Steels, glasses, plastics, and composites also are used widely to make
automotive.
– Often in these applications, combinations of strength, stiffness, and toughness
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Classification of Materials Based on Structure

• As mentioned before, the term “structure” means the
arrangement of a material’s atoms;
– the structure at a microscopic scale is known as
“microstructure.” We can view these arrangements at different
scales, ranging from a few angstrom units to a millimeter.
– We will learn in Chapter 3 that some materials may be crystalline
(the material’s atoms are arranged in a periodic fashion) or they
may be amorphous (the arrangement of the material’s atoms
does not have long-range order).
– Some crystalline materials may be in the form of one crystal and
are known as single crystals.
– Others consist of many crystals or grains and are known as
polycrystalline. The characteristics of crystals or grains (size,
shape, etc.) and that of the regions between them, known as the
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Environmental and Other Effects

• The structure-property relationships in materials

fabricated into components are often influenced by the
surroundings to which the material is subjected during
use.
• This can include exposure to high or low temperatures,
cyclical stresses, sudden impact, corrosion, or oxidation.
These effects must be accounted for in design to ensure
that components do not fail unexpectedly.

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Environmental and Other Effects Con…

• Temperature
– Changes in temperature dramatically alter the properties of materials.
– Metals and alloys that have been strengthened by certain heat treatments or
forming techniques may suddenly lose their strength when heated.
• Eg. A tragic reminder of this is the collapse of the World Trade
Center towers on September 11, 2001.
– High temperatures change the structure of ceramics and cause polymers to
melt or char.
– Very low temperatures, at the other extreme, may cause a metal or polymer
to fail in a brittle manner, even though the applied loads are low.
• Eg. This low-temperature embrittlement was a factor that caused
the Titanic to fracture and sink.
• the 1986 Challenger accident, in part, was due to embrittlement
of rubber O-rings.

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Environmental and Other Effects Con…

• Corrosion
– Most metals and polymers react with oxygen or other gases,
particularly at elevated temperatures.
– Metals and ceramics may disintegrate and polymers and non-
oxide ceramics may oxidize.
– Materials also are attacked by corrosive liquids, leading to
premature failure. The engineer faces the challenge of selecting
materials or coatings that prevent these reactions and permit
operation in extreme environments.
– In space applications, we may have to consider the effect of
radiation.

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Environmental and Other Effects Con…

• Fatigue
– In many applications, components must be designed such that the
load on the material may not be enough to cause permanent
deformation.
– When we load and unload the material thousands of times, even at
low loads, small cracks may begin to develop, and materials fail as
these cracks grow. This is known as fatigue failure.
– In designing load-bearing components, the possibility of fatigue
must be accounted for.

• Strain Rate
– Many of you are aware of the fact that Silly Putty®, a silicone-
(notsilicon-) based plastic, can be stretched significantly if we pull it
slowly (small rate of strain).
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Materials Design and Selection

• When a material is designed for a given application, a number of
factors must be considered.
– The material must acquire the desired physical and mechanical
properties,
– must be capable of being processed or manufactured into the desired
shape, and
– must provide an economical solution to the design problem.
– Satisfying these requirements in a manner that protects the
environment perhaps by encouraging recycling of the materials is also
essential.
• In meeting these design requirements, the engineer may have to
make a number of trade-offs in order to produce a serviceable, yet
marketable, product.

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The Materials Selection Process

Pick Application Determine required Properties
1.
Properties: mechanical, electrical, thermal,
magnetic, optical, deteriorative.
Properties Identify candidate Material(s)
2.
Material: structure, composition.
Material Identify required Processing
3.
Processing: changes structure and overall shape
ex: casting, sintering, vapor deposition, doping
forming, joining, annealing.

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Conclusion
• By this point of our discussion, we hope that you can appreciate
that the properties of materials depend not only on composition,
but also how the materials are made (synthesis and processing)
and, most importantly, their internal structure. This is why it is
not a good idea for an engineer to refer to a handbook and select
a material for a given application.

• The handbooks may be a good starting point. A good engineer

will consider: the effects of how the material was made, the
exact composition of the candidate material for the application
being considered, any processing that may have to be done for
shaping the material or fabricating a component, the structure of
the material after processing into a component or device, the
environment in which the material will be used, and the cost-to-
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examples
1. Coiled springs ought to be very strong and stiff. Si3N4 is a strong, stiff
material. Would you select this material for a spring? Explain.

2. properties should the head of a carpenter’s hammer possess? How would

you manufacture a hammer head?

3. You would like to design an aircraft that can be flown by human power
nonstop for a distance of 30 km. What types of material properties would
you recommend? What materials might be appropriate?

4. You would like to select a material for the electrical contacts in an

electrical switching device which opens and closes frequently and
forcefully. What properties should the contact material possess? What
type of material might you recommend? Would Al2O3 be a good choice?
Explain
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examples

2. Describe the enabling materials property of each

of the following and why it is so:
a. aluminum for airplane bodies;
b. polyurethane for teeth aligners (invisible
braces);
c. (steel for the ball bearings in a bicycle’s wheel
hub;
d. polyethylene terephthalate for water bottles;
and
e. glass for wine bottles.
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