1. MS115a Principles of Materials Science Fall 2010
Instructor:
Prof. Sossina M. Haile
307 Steele Laboratories, x2958,
Class Meetings: MWF 9-10am, 214 Steele
Teaching Assistants:
Nick Heinz, 303 Steele, x1711,
Balaji Gopal (BG) Chiranjeevi, 302 Steele, x2777,
TA Office Hours: TBA (likely Tuesdays)
Required Text: None
Recommended Text: “Intro to Mat Sci for Engineers” Shackelford
Reserved Texts: SFL
“The Principles of Engineering Materials,” Barrett, Nix & Tetelman
“Phase Transformations in Metals and Alloys,” Porter & Easterling
“Quantum Chemistry,” Levine

2. What is Materials Science?
Chemistry / Composition
Processing +
Structure  ?  ?
Properties / Performance
thermodynamics
kinetics
MS 115b
MS 115a

3. Course Content Introduction to Materials Science Structure
Chemistry + Processing  Structure  Properties
Structure
Structure of the Atom & Introduction to Chemical Bonding
Crystalline Structure
Structural Characterization (X-ray diffraction)
Amorphous Structure
Microstructure
Defects in Crystalline Solids, Connections to Properties
Point Defects (0-D) and Diffusion & Ionic Conductivity
Dislocations (1-D) and Mechanical Deformation
Surfaces and interfaces (2-D)
Volume Defects (3-D) and Fracture

4. Course Content Electrons in Solids Thermodynamics
Chemical Bonding, Revisited
Band Structure
Electronic Conductivity: Metals vs. Insulators
Thermodynamics
1st and 2nd Laws
Gibb’s Free Energy
Phase Diagrams
Some Other Properties Along the Way
Thermal: Thermal Expansion, Heat Capacity, Thermal Conductivity
Optical: Refraction, Reflection; Absorption, Transmission, Scattering, Color
Conceptual vs. Highly Mathematical

5. Course Structure Homework: weekly 50% Midterm HW: Oct 27 - Nov 2 15%
Assigned Wednesdays
Due following Wednesday, 5pm
Place in TA mailbox, 3rd floor Steele
Midterm HW: Oct 27 - Nov 2 15%
Solo homework
Final: Dec %
Take home

6. HW Collaboration Policy
Students are encouraged to discuss and work on problems together.
During discussion, you may make/take notes
However, do not bring and/or exchange written solutions or attempted solutions you generated prior to the discussion.
If you’ve worked the problem out and you plan to help a friend, you should know the solution cold.
Do not consult old problem sets, exams or their solutions.
Solutions will be handed out on Friday, or possibly Monday. Assignments turned in late, but before solutions are available, will receive 2/3 credit. Assignments will not be accepted after solutions are handed out.

7. Midterm Homework
In lieu of a midterm exam there will be homework to be performed on an individual basis. This homework must be completed without collaborative discussion.
The problem set will focus primarily on recent lectures, but material from early topics may also be included.
Similar to other homeworks, you will have one week to complete the assignment.
You are permitted to utilize all available resources, with the exception of previous solutions, including ones from earlier in the year.

9. Structure of the Atom
“Electron in a box” – use quantum mechanics to solve electron wave functions
Electron quantum numbers, orbitals
Electrical properties
Qualitative description of chemical bonding
Electrons ‘orbit’ atomic nucleus
Q.N. n
K, L, M
“shell”
n = 1, 2, 3  radius l
s, p, d
“orbital”
l = 0, 1 …. n-1 m
px, py, pz
“orientation”
m = -l, -l + 1, …0,...l - 1, l s
spin
s = ± ½
Chemical notation K L 1 M 2
K-shell: n = 1
 l = 0
 1s
 m = 0
s = ± ½ 3
 2s, 2p
L-shell: n = 2
 l = {0, 1}
m = 0
m = {-1, 0, 1}
 px. py. pz

10. Structure of the Atom Electrons occupy these orbitals
Pauling exclusion principle
Only one electron with a given set of QNs
For a multi-electron atom, fill up orbitals beginning with lowest energy & go up
Order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s,..

11. Chemical Bonding Noble gases: filled outer shell, limited chemistry
Atoms  Molecules  Solids
Bonds form so as to produce filled outer shells
Some atoms are a few electrons short
Electronegative: readily pick up a few electrons from other atoms, become negatively charged
Some atoms have a few electrons too many
Electropositive: readily give up a few electrons to other atoms, become positively charged
Noble gases: filled outer shell, limited chemistry

12. electronegativity

13. Types of Chemical Bonds
Primary
Ionic
Electronegative/Electropositive
Metallic
Electropositive – give up electrons
Colavent
Electronegative – want electrons
Shared electrons along bond direction
Secondary
Fluctuating/instantaneous dipoles
Permanent dipoles (H-bonds)
Isotropic, filled outer shells + - + e-

14. Some Properties The bond energy curve E = ER + EA E E0 R0
short range repulsion
E = ER + EA E R0
R (interatomic distance) E0
long range attraction
R0 : interatomic distance that minimizes E
is the equilibrium bond distance
E0 : decrease in energy due to bond formation
this much energy is required to break the bond
define as bond energy
sets the melting temperature

15. More Properties Heat the material E Ethermal = kbT R0  as T  T 
E = ER + EA E
R (interatomic distance)
R0  as T 
T 
Ethermal = kbT
Asymmetry in E(R) sets thermal expansion coefficient

16. Some Mechanical Properties
R (interatomic distance) R0 E0
F = dE/dR
The bond force curve
Elastic constants relate stress to strain
Stress – related to force
Strain – related to displacement
at R0 no net force (equilibrium bond distance)
attractive
F = k Dx F k
stress*area
strain*length R0
R (interatomic distance)
stress  k strain
repulsive
Elastic constants given by slope of B.F. curve at R0
given by curvature of B.E. curve at R0

17. Summary
Nature of the bonds formed depends on the chemical nature of the elements (as given by placement on the periodic table)
Bond energy / bond force curve gives
Equilibrium bond distance
Melt temperature
Thermal expansion coefficient
Elastic constants
In general, there is not a correlation between the type of bond and the value of the property