MAE 301 Lecture 1
Transcript of MAE 301 Lecture 1
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MAE 301: Engineering
Materials Science
Introduction to Engineering
Materials Science
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Introduction Engineering Materials
Science
Course Objective...Introduce fundamental concepts in Materials
ScienceYou will learn about:
material structure how structure dictates properties how processing can change structure
This course will help you to: use materials properly realize new design opportunities
with materials
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Introduction to Engineering
Materials Science
Materials drive our society Materials are probably more deeply rooted in our
society than most realize (e.g. electronics,
communication, aerospace/transportation,housing, etc)
The development of many technologies have beenintimately associated with accessibility to newmaterials.
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These materials are used to create everything from those small things we don't
think about, such as dashboard needles and wiring, to the big stuff, such as
the engine block or the transmission gears.
Automobile Industry
Steel (including high-strength steels)
Aluminum
Plastics, rubber
Glass
Copper
Iron
Magnesium Composite materials
Materials Make Technology Possible
Examples:
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Materials Drive our Society
High-strength alloy steels are
used for Submarine hulls
Steel and Aluminum are used in
building Passenger Ships Nickel, Aluminum, Bronze alloys
are used for marine Propellers
High strength steel alloys,
Aluminum, Carbon fiber, and PVC-
related Plastics are used in High
Speed Rail
Transportation by Sea and Rail
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Materials Make Technology Possible
Al-Li alloys are used in jetliner airframes. Theyare superior to aluminum alloys in strength andstiffness, so can be used to save weight. But they
are ~ 3x as expensive.
Commercial Airplanes are mostly built using
Aluminum Alloys.
Newer planes are built with some Composite
Materials.
Jet engines often use Titanium. Some military
aircraft use Titanium for structural and body
pieces.
Special Ceramics are used for the heat shield
of the space shuttle
Aerospace Industry: Aerospace materials must be lightweight and strong.
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Materials in Sports Equipment
Sports equipment uses
almost advanced metal
alloys, ceramics, polymers,
and composites, as athletesand designers leverage
state-of-the-art materials to
maximize human efficiency,
performance, comfort and
safety.
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Prosthetic devices often
need to be lightweight.
They are typically made from
Polymeric materials(polyethylene, polypropylene,
acrylics, and polyurethane ),
Lightweight metals alloys of
titanium and aluminum, and
Composites (such as carbonfiber reinforced composites).
Materials in Biomedical Engineering
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Example Hip Implant
Adapted from Fig. 22.25, Callister 7e.
X-Rays of a normal hip joint (left) and a fractured hip joint (right). The
arrows show the two ends of the fracture line through the femoral neck.
With age or certain illnesses joints deteriorate, particularly joints withlarge loads (such as hip).
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Materials for Hip Implant
Materials Requirements
mechanical strength
(many cycles)
good lubricity
Biocompatibility
lightweight components
Reasonable cost
Adapted from Fig. 22.24, Callister 7e.
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Hip Implant
Adapted from Fig. 22.26, Callister 7e.(a) Schematic diagram and (b) x-ray of an artificial total hip replacement.
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Hip Implant
Key problems to overcome
fixation agent to hold
acetabular cup
cup lubrication material
femoral stem fixing agent
must avoid any debris in cup
FemoralStem
Ball
AcetabularCup and Liner
Adapted from chapter-opening photograph,
Chapter 22, Callister 7e.
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Hip Implant Materials
Femoral Stem: Materials used include:
Stainless steel, 316L (Cold worked)
Titanium-aluminum-vanadium Alloy, Ti-6Al-4V, (HotForged)
Cobalt-chromium-molybdenum Alloy, Co-28Cr-6Mo, (Cast)
Ball Component: Materials used include
high-purity, polycrystalline aluminum oxide orzirconium
oxide. These ceramic materials are harder and more wearresistant than metals, and generate lower frictional stressesat the joint.
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Hip Implant Materials
Acetabular Cup: The inner-cup is often made fromultra-high molecular weight polyethylene, which isvirtually inert in the body and has excellent wearresistance, and a low coefficient of friction with the ballmaterial. The outer cup is fabricated from one of themetal alloys used for the femoral stem.
Fixation Agent: The most common is polymethyl
methacrylate (acrylic) bone cement.
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Hip Implant Example
Hip Implant Example illustrated the need fortailor-made
materials for this human need.
The solution required:
Knowledge of the responses of the various materials (e.g.Ti-6Al-4V, Al2O3, ZrO2, polyethylene, etc.) when exposed to external
stimuli (properties).
Knowledge of the effect of alloying elements and fabrication
processes (casting, forging, cold working,..) on the internal make-
up of the material (material structures).
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Materials Science and Engineering
The ability to fashion materials to fit a wide variety ofneeds is a capability unique to our modern society.
Early Metallurgy
Used metals like Copper, Tin, Silver, Iron Understood that material properties could be altered by alloying
and heat treatment
Modern Materials Science Involves the relationships between the underlying structures ofmaterials and the resultant properties
This knowledge allows materials to be tailor-made for a variety ofneeds.
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Materials Science and Engineering
Materials science
Involves investigating the relationship
between the structures of materials and their
properties
Materials Engineering
Engineering the structures of materials toproduce a predetermined set of properties
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Material Structures
This is the arrangement of the internal components of amaterial:
Subatomic structure: involve the electrons within the individualatoms and interactions with their nuclei
Atomic level Structure: the organization of atoms or moleculeswith respect to one another
Microscopic Structure: large groups of atoms that are
agglomerated together
Macroscopic Structure: Structural elements that can be viewedwith the naked eys
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Sub-Atomic Structure Atomic Structure
Microstructure Macrostructure
Material Structures
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Common Material Properties
Mechanical (deformation resulting from an applied load)
Electrical (e.g. Electrical Conductivity)
Thermal (Thermal conductivity, heat capacity)
Magnetic (Response to a magnetic field)
Optical (Response to an electromagnetic field. e.g.
reflection, transmission, refractive index)
Deteriorative (Corrosion, Response to chemical activity)
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Processing Structure
Properties Performance
Processing, Structure, Properties,
& Performance
Goal: To tailor-make/design materials with precise properties.
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ex: hardness vs structure of steel Propertiesdepend onstructure
Data obtained from Figs. 11.31(a)
and 11.33 with 4 wt% C composition,
and from Fig. 14.8 and associated
discussion, Callister & Rethwisch 3e.
Micrographs adapted from (a) Fig.
11.19; (b) Fig. 10.34;(c) Fig. 11.34;
and (d) Fig. 11.22, Callister & Rethwisch 3e.
ex: structure vs cooling rate of steel Processing can change structure
Structure-Property Relationships
H
ardness(BHN)
Cooling Rate (C/s)
100
2 00
3 00
4 00
5 00
6 00
0.01 0.1 1 10 100 1000
(d)
30mm
(c)
4mm
(b)
30mm
(a)
30mm
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Types of Materials Metals:
Composed of one or more metallic elements Strong, ductile, High thermal & electrical conductivity
Opaque, reflective.
Polymers: Very large molecular structures based on C, H, and nonmetals
Soft, ductile, low strength, low density, translucent or transparent
Thermal & electrical insulators, chemically inert
Ceramics: compounds of metallic & nonmetallic elements (oxides,carbides, nitrides, sulfides).
Stiff and strong (similar to metals). High temperature resistant.
Very hard, extremely brittle, Non-conducting (insulators)
Composites: Composed of two or more individual materials
(metals, ceramics, or polymers), with a combination of properties
not displayed by any single material.
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Metals
Typical Metal Items
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Examples of Ceramics
Silicon nitride (Si3N4) ceramics have goodshock resistance compared to other
ceramics. Si3N4 ball bearings are used in
the main engines of the Space Shuttle.
They areharder than metal
have 80% less friction;
last 3 to 10 times longer;
operate at 80% higher speed;
weigh 60% less;operate with lubrication starvation;
have higher corrosion resistance
higher operation temperature,
compared to metal bearings.
Typical Ceramic Items
Silicon Nitride Items
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Two main types of p olymers arethermosetsandthermoplast ics.
Thermosets are cross-linked polymers that form 3-D networks, hence are strong
and rigid.
Thermoplastics are long-chain polymers that slide easily past one another when
heated, hence, they tend to be easy to form, bend, and break.
Polymers
Typical Polymeric Items
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Materials Selection
Engineers will at one time or another have tomake design decisions involving materials.
Many time a materials problem is one of
selecting the right material for the design from amany alternatives
Rarely does a material possess the idealcombination of properties, and trade-off arenecessary. A material may have the idealcombination of properties but may beexpensiveand compromise is necessary.
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1. Pick Application Determine required Properties
Processing: changes structure and overall shapeex: casting, sintering, vapor deposition, doping
forming, joining, annealing.
Properties: mechanical, electrical, thermal,
magnetic, optical, deteriorative.
Material: structure, composition.2. Properties Identify candidate Material(s)3. Material Identify required Processing
The Materials Selection Process
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ELECTRICAL Electrical Resistivity of Copper:
Adding impurity atoms to Cu increases resistivity. Deforming Cu increases resistivity.
Adapted from Fig. 12.8, Callister &
Rethwisch 3e. (Fig. 12.8 adapted
from: J.O. Linde,Ann Physik5, 219
(1932); and C.A. Wert and R.M.
Thomson, Physics of Solids, 2nd
edition, McGraw-Hill Company, New
York, 1970.)
T(C)-200 -100 0
1
2
3
4
5
6
Resistivity,r
(10-8O
hm-m)
0
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THERMAL Space Shuttle Tiles:
-- Silica fiber insulation
offers low heat conduction.
Thermal Conductivity
of Copper:
-- It decreases whenyou 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. 17.4, Callister & Rethwisch
3e. (Fig. 17.4 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.)
Composition (wt% Zinc)
ThermalCond
uctivity
(W/m-K
)
400
300200
100
00 10 20 30 40
100mm
Adapted from chapter-
opening photograph,
Chapter 17, Callister &
Rethwisch 3e. (Courtesy
of Lockheed
Missiles and Space
Company, Inc.)
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MAGNETIC
Magnetic Permeabilityvs. 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.
Fig. 18.23, Callister & Rethwisch 3e.
(Fig. 18.23 is from J.U. Lemke, MRS Bulletin,
Vol. XV, No. 3, p. 31, 1990.)
Magnetic Storage:-- Recording medium
is magnetized by
recording head.
Magnetic FieldM
agnetization Fe+3%Si
Fe
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Transmittance:-- Aluminum oxide may be transparent, translucent, oropaque depending on the material structure.
Adapted from Fig. 1.2,
Callister & Rethwisch 3e.
(Specimen preparation,
P.A. Lessing; photo by S.
Tanner.)
single crystal
polycrystal:
low porosity
polycrystal:
high porosity
Example: Optical Properties of
Aluminum Oxide
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DETERIORATIVE Stress & Saltwater...
-- causes cracks!
Adapted from chapter-opening photograph,
Chapter 16, Callister & Rethwisch 3e.
(from Marine Corrosion, Causes, and
Prevention, John Wiley and Sons, Inc., 1975.)
4mm-- material:7150-T651 Al "alloy"
(Zn,Cu,Mg,Zr)
Adapted from chapter-opening
photograph, Chapter 11, Callister & Rethwisch 3e.(Provided courtesy of G.H. Narayanan and A.G. Miller,
Boeing Commercial Airplane Company.)
Heat treatment: slowscrack 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.)
held at160C for 1 hrbefore testing
increasing loadcracks
peed(m/s)
as-is
10-10
10-8
Alloy 7178 tested insaturated aqueous NaClsolution at 23C
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Use the right material for the job.
Understand the relation between properties,structure, and processing.
Recognize new design opportunities offered
by materials selection.
Course Goals:
SUMMARY
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Review Assignment
Chapter 1
Question 1.1
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Reading Assignment
Chapter 2.1 2.8
Atomic Structures
Interatomic Bonding Forces and Energies Primary and Secondary Bonds