MIE 201: Introduction to Materials

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MIE 201 Introduction to Materials
Lecturer Prof J. I. Goldstein
Elab 313, jig0_at_ecs.umass.edu

Web Site
http//mielsvr1.ecs.umass.edu/mie201
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MIE 201 Introduction to MaterialsCourse Goals

• To comprehend broad classification of
• materials (metals, ceramics, polymers, etc.)
  based on bonding, structure and properties
• To understand how material properties depend on
  composition, structure, processing
• To select materials for design, production, and
  end use

See comprehensive list of course goals and
outcomes on web site
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Mechanical Failure
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Materials Classification Metals

• Pure elements or combinations of metallic
  elements (alloys) metallic bonding
• Good electrical conductors
• Good heat conductors
• Shiny appearance - not transparent
• Strong
• Deformable
• Sometimes magnetic

Structural feature
Dimension (m)
-10
lt 10
atomic bonding

-10
10
-8
-1
crystals (ordered atoms)
10
-10
second phase particles
-8
-4
10
-10
crystal texturing
-6
gt 10
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Materials Classification Ceramics

• Compounds between metallic and non-metallic
  elements - Ionic or covalently bonded
• Hard
• Brittle
• Electrical insulators
• Poor thermal conduction
• Heat and corrosion resistant
• Can be tranparent or opaque

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Materials Classification Polymers

• Organic compounds based on C, H and other
  non-metallic elements covalent and secondary
  bonding
• Huge variety of properties
• Low densities
• Non conductors
• Low melting points
• Can be very flexible

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Other sub-classes of materials

• Composites
• which consist of more than one material type
• Semiconductors
• have electrical properties that are intermediate
  between that of conductors and insulators
• Biomaterials
• - materials for implanting in the human body

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Materials Selection
1.
Pick Application
Determine required Properties
mechanical, electrical, thermal, magnetic,
optical, corrosion resistance.
2.
Properties
Identify candidate Material(s)
Material structure, composition.
3.
Material
Identify required Processing
Processing changes structure and overall
shape ex casting, sintering, vapor deposition,
doping, forming, joining, annealing.
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LECTURES
Lecturer Prof J. I. Goldstein
Elab 313, jig0_at_ecs.umass.edu
Time Mon, Wed, Fri 840 to 955 AM
Location 119 ECSCII
Activities
Present new material
Discuss reading and homework
2 Exams

• Class Quizzes

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RECITATIONS
Dates,Times See course calendar





Purpose
Discuss homework, quizzes and sample exams

• Discuss concepts from lecture

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COURSE MATERIAL
Required text
Fundamentals of Materials Science and
Engineering An Integrated Approach, 3nd Edition
W.D. Callister, Jr. ,David G. Rethwisch John
Wiley and Sons, Inc. (2004). Both book and web
materials are needed.
Lecture slides are posted on the web just before
class
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Reading Schedule
See the detailed course syllabus which is posted
on the web
Homework Schedule
See the Homework Page of the web site
Web Site
Go to http//mielsvr1.ecs.umass.edu/mie201 Course
announcements will be listed on the Announcements
Page
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GRADING
Class Attendance
Regular attendance is critical for good success
in the course
Weekly homework problems 20
Two in Class Exams 20 each
Final Exam 30
To be scheduled
In class Quizzes 10
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Atomic Structure
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CHAPTER 2Atomic Structure and Interatomic
Bonding
ISSUES TO ADDRESS...
What promotes bonding?
What types of bonds are there?
What properties are inferred from bonding?
1
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BOHR ATOM
Adapted from Fig. 2.1, Callister 6e.
Nucleus Z protons
1 for hydrogen to 94 for plutonium
N neutrons
Atomic mass A Z N
2
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ELECTRON ENERGY STATES
Electrons...
have discrete energy states tend to occupy
lowest available energy state.
0
Adapted from Fig. 2.5, Callister 6e.
-
3
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STABLE ELECTRON CONFIGURATIONS
Stable electron configurations...
have complete s and p subshells tend to be
unreactive.
Adapted from Table 2.2, Callister 6e.
4
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SURVEY OF ELEMENTS
Most elements Electron configuration not
stable.
Adapted from Table 2.2, Callister 6e.
Why? Valence (outer) shell usually not filled
completely.
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Periodic Table
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Electronegativity
Smaller electronegativity
Larger electronegativity

• Varies between 0.7 and 4.0
• Large values tendency to acquire electrons.

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IONIC BONDING
Occurs between and - ions. Requires
electron transfer. Large difference in
electronegativity required.
Example NaCl
Cation
Anion
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Attractive forces are Coulombic and non
directional Attractive energy EA
-A/r Repulsive energy ER B/rn (where n8)

• Non-conducting
• Hard
• Brittle
• Thermal insulator

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Interatomic Potential Energy Curves
Energy
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COVALENT BONDING
Requires shared electrons
Example CH4
C has 4 valence e, needs 4 more
H has 1 valence e, needs 1 more
Electronegativities are comparable.
Adapted from Fig. 2.10, Callister 6e.
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Diamond
Covalent bonding is directional and strong
Covalent solids are hard, brittle and
non-conducting
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METALLIC BONDING
Primary bond for metals and their alloys
Arises from a sea of donated valence electrons
(1, 2, or 3 from each atom).
-
-
Good electrical and thermal conductors as a
consequence of the free electrons
-
-
-
-
-
-
-
Adapted from Fig. 2.11, Callister 6e.