KNJ 1433 Engineering Materials
Week 1:
Introduction to Materials
Semester 1 2016/2017
1
Aims of the course
• To provide students with the basic and relevant
theory/knowledge, evaluation, analysis and application
of the engineering materials.
• This course includes introduction to materials, atomic
structure and inter-atomic bonding, the structure of
crystalline solids, phase equilibrium diagram,
mechanical properties of engineering materials and
their determination, deformation and dislocation,
engineering applications of materials, properties and
applications of Polymers, Ceramics and Composite
Materials, degradation-corrosion and failure of
2
Materials.
Course Outcomes
By the end of this course, students should be able to:
• Classify the types of materials and distinguish between their
properties resulting from three various crystal structures in solids
based on atomic packing, their microstructures, crystal defects and
composition, strengthening mechanisms, failure mechanisms and
degradation through chemical and electrochemical process such as
corrosion.
• Use the binary diagram in predicting the microstructure and
composition of phase, and use the stress-strain curve to measure
and predict the mechanical properties of the materials.
• Design materials for Mechanical and Manufacturing applications
through comparison of the mechanical & physical properties of
Engineering materials.
3
Topics
•
•
•
•
•
•
•
•
•
•
Introduction to Materials
Atomic Structure and Inter-atomic Bonding
The Structure of Crystalline Solids
Phase Equilibrium Diagrams
Mechanical Properties of Engineering Materials
Reinforcement Mechanisms
Corrosion of Metals
Failure of Materials
Engineering Ceramics
Selection and Application of Materials
4
Assessment
Test 1 & 2
20%
Final Exam
50%
Quiz/ Assignment
30%
5
References:
1. W. D. Callister, D. G. Rethwisch (2013). Materials
Science and Engineering. 9th Edition, John Wiley and
Sons, USA.
2. W. F. Smith, J. Hashemi (2010). Foundations of
Materials Science and Engineering (SI Units). 5th
Edition, McGraw Hill Publishers.
3. K. G. Budinski, M. K. Budinski (2009). Engineering
Materials: Properties and Selection. 9th Edition,
Pearson Education Series, USA
4. M. F. Ashby (2010). Materials Selection in Mechanical
Design. 4th Edition, Butterworth Heinnemen, Elsevier,
USA
6
Introduction to Engineering
Materials
• Materials Science and Materials Engineering
Materials science
Search for basic knowledge
about:
• internal structure
• properties and
• processing of materials
Materials engineering
Use of fundamental and applied
knowledge of materials so that it
can be utilised
• products
7
Why study Engineering Materials?
• Select right material among thousands of them
for certain cases – mechanical properties,
corrosion resistance, cost, etc.
• Several criteria involved in selecting right
materials such as:
– In-service condition-dictate the properties required of
the materials.
– Any deterioration of materials properties that may
occur during service operation. (e.g. : reduction of
mechanical strength as a result from exposure to high
temperature or corrosive environment).
– Cost of finished product
8
Classification of materials
• 6 main types:
1.Metals
2.Ceramics
Fundamental class
3.Polymers
4.Composites
5.Electronic
Process/application class
6.Biomaterial
7.Materials for future – smart material, nano
9
Classification of Materials
1.
2.
3.
Metals: Materials in this group are composed of one or more metallic
elements (e.g. iron, aluminium, copper, titanium, gold, and nickel), and often
also non-metallic elements(e.g.. Carbon, nitrogen. and oxygen) in relatively
small amounts.
Ceramics: Ceramics are compounds between metallic and nonmetallic
elements; they are most frequently oxides, nitrides and carbides. For example,
common ceramic materials include aluminum oxide (or alumina, A1203),
silicon dioxide (or silica, SiO2), silicon carbide (SiC), silicon nitride (Si3N3), and in
addition, what some refer to as the traditional ceramics—those composed of
clay minerals (i.e. porcelain), as well as cement and glass With regard to
mechanical behaviour, ceramic materials are relatively stiff and strong—
stiffness and strengths are comparable to those of the metals.
Polymers: Polymers include the familiar plastic and rubber materials. Many of
them are organic compounds that are chemically based on carbon, hydrogen,
and other non metallic elements (i.e. O, N, and Si). Furthermore, they have
very large molecular structures, often chainlike in nature, that often have a
backbone of carbon atoms. E.g. PE, PVC, PP, PS, PC.
10
Classification of Materials
4.
5.
Composites: Composed of two (or more) individual materials, which come from
the categories previously discussed—metals, ceramics, and polymers. The
design goal of a composite is to achieve a combination of properties that is not
displayed by any single material, and also to incorporate the best characteristics
of each of the component materials. A large number of composite types are
represented by different combinations of metals, ceramics. and polymers.
Furthermore, some naturally occurring materials are composites—for example,
wood and bone. However, most of those we consider in our discussions are
synthetic (or human-made)composites. (e.g. GFRP, CFRP etc.).
Electronic (Semiconductors): have electrical properties that are intermediate
between the electrical conductors (i.e., metals and metal alloys) and insulators
(i.e., ceramics and polymers). Furthermore, the electrical characteristics of
these materials are extremely sensitive to the presence of minute
concentrations of impurity atoms, for which the concentrations may be
controlled over very small spatial regions. Semiconductors have made possible
the advent of integrated circuitry that has totally revolutionized the electronics
and computer industries (not to mention our lives) over the past three decades.
11
Comparison of Properties
Density
Stiffness
Strength
Toughness
12
Classification of Materials
6.
7.
Biomaterials: Biomaterials are employed in components implanted into the
human body to replace diseased or damaged body parts. These materials must
not produce toxic substances and must be compatible with body tissues (i.e.,
must not cause adverse biological reactions). All of the preceding materials—
metals, ceramics, polymers, composites, and semiconductors—may be used as
biomaterials. (i.e., artificial hip replacement)
A) Smart Materials: Smart (or Intelligent) materials are a group of new and
state-of-the-art materials now being developed that will have a significant
influence on many of our technologies. The adjective smart implies that these
materials are able to sense changes in their environment and then respond to
these changes in predetermined manners—traits that are also found in living
organisms. In addition, this smart concept is being extended to rather
sophisticated systems that consist of both smart and traditional materials. (i.e.,
sensor – detect input signal  actuator – performs a respond/adaptive
function.)
13
Classification of Materials
7.
B) Nanomaterials: Nanomaterials may be any one of the four basic types—
metals, ceramics, polymers, and composites. They are not distinguished on the
basis of their chemistry, but rather, size; the nano-prefix denotes that the
dimensions of these structural entities are on the order of a nanometer (10-9
m) —as a rule, less than 100 nanometers (equivalent to approximately 500
atom diameters). Prior to the advent of nanomaterial, the general procedure
scientists used to understand the chemistry and physics of materials was to
begin by studying large and complex structures, and then to investigate the
fundamental building blocks of these structures that are smaller and simpler.
This approach is sometimes termed ‘top-down science.
Electrical
property
14
Processing/ Structure/ Properties/ Performance
Correlations
• Properties depend on structure
ex: hardness vs structure of steel
Hardness (BHN)
(d)
600
500
400
(c)
(a)
(b)
4m
300
200
30m
30m
100
0.01 0.1
30m
Data obtained from Figs. 10.21(a)
and 10.23 with 4wt%C composition,
and from Fig. 11.13 and associated
discussion, Callister 6e.
Micrographs adapted from (a) Fig.
10.10; (b) Fig. 9.27;(c) Fig. 10.24;
and (d) Fig. 10.12, Callister 6e.
1
10 100 1000
Cooling Rate (C/s)
• Processing can change structure
ex: structure vs cooling rate of steel
15
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.
Electrical, Thermal, Magnetic, Optical
3.
Material
Identify required Processing
Processing: changes structure and overall shape
ex: casting, sintering, vapour deposition, doping
forming, joining, annealing.
16
ELECTRICAL
• Electrical Resistivity of Copper:
Adapted from Fig. 18.8, Callister 6e.
(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.)
• Adding “impurity” atoms to Cu increases resistivity.
• Deforming Cu increases resistivity.
17
• Space Shuttle Tiles:
THERMAL
• Thermal Conductivity
--Silica fiber insulation
offers low heat conduction.
Fig. 19.0, Callister 6e.
(Courtesy of Lockheed
Missiles and Space
Company, Inc.)
of Copper:
--It decreases when
you add zinc!
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 6e.
(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.)
18
• Magnetic Storage:
MAGNETIC
--Recording medium
is magnetized by
recording head.
Fig. 20.18, Callister 6e.
(Fig. 20.18 is from J.U. Lemke, MRS Bulletin,
Vol. XV, No. 3, p. 31, 1990.)
•
Magnetic Permeability
vs. Composition:
--Adding 3 atomic % Si
makes Fe a better
recording medium!
Adapted from C.R. Barrett, W.D. Nix, and
A.S. Tetelman, The Principles of
Engineering Materials, Fig. 1-7(a), p. 9,
1973. Electronically reproduced
by permission of Pearson Education, Inc.,
Upper Saddle River, New Jersey.
19
• Transmittance:
OPTICAL
--Aluminum oxide may be transparent, translucent, or
opaque depending on the material structure.
single crystal
polycrystal:
low porosity
polycrystal:
high porosity
Adapted from Fig. 1.2,
Callister 6e.
(Specimen preparation,
P.A. Lessing; photo by J.
Telford.)
20
DETERIORATIVE
• Stress & Saltwater...
--causes cracks!
Adapted from Fig. 17.0, Callister 6e.
(Fig. 17.0 is from Marine Corrosion, Causes,
and Prevention, John Wiley and Sons, Inc.,
1975.)
• Heat treatment:
slows
crack speed in salt water!
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.)
--material:
4m
7150-T651 Al "alloy"
(Zn,Cu,Mg,Zr)
Adapted from Fig. 11.24,
Callister 6e. (Fig. 11.24 provided courtesy of G.H.
Narayanan and A.G. Miller, Boeing Commercial
Airplane Company.)
21
Summary
Materials Science and Engineering.
• 6 different property classifications of materials that determine their applicability: mechanical,
electrical, thermal, magnetic, optical, and deteriorative.
• One aspect of materials science is the investigation of relationships that exist between the
structures and properties of materials.
• With regard to the design, production, and utilization of materials, there are 4 elements to
consider— processing, structure, properties, and performance.
• Three important criteria in materials selection are in-service conditions to which the material will
be subjected, any deterioration of material properties during operation, and economics or cost of
the fabricated piece.
Classification of Materials.
• On the basis of chemistry and atomic structure, materials are classified into three general
categories: metals (metallic elements), ceramics (compounds between metallic and nonmetallic
elements), and polymers (compounds composed of carbon, hydrogen, and other nonmetallic
elements). In addition, composites are composed of at least two different material types.
Advanced Materials.
• Used in high-tech applications. These include semiconductors (having electrical conductivities
intermediate between conductors and insulators), biomaterials (which must be compatible with
body tissues), smart materials (those that sense and respond to changes in their environments in
predetermined manners), and nanomaterials (those that have structural features on the order of a
nanometer. some of which may be designed on the atomic/molecular level).
22