Lecture 8: Surface tension, internal pressure and energy of a spherical
particle or droplet
Todays topics
Understand what is surface tension or surface energy, and how this balances with the
internal pressure of a droplet to determine the droplet size.
Wh
Lecture 15: Kinetics of Phase Growth: single-component or
composition-invariant transformation
Todays topics
Derivation of the Johnson-Mehl-Avrami equation: the time constant () of phase growth
and the S shape plot describing the kinetics of phase transfo
Lecture 16: Kinetics of Phase Growth in a Two-component System:
dilute-solution approximation
Todays topics
Kinetics of phase growth (transformation) in a two-component system: atom A and B form
two phases and , which are dominated by A and B, respectivel
Lecture 18: Kinetics of Phase Growth in a Two-component System:
general kinetics analysis based on the dilute-solution approximation
Todays topics:
In the last 2 Lectures, we learned three different ways to describe the diffusion flux of B
atoms across th
Lecture 17: Kinetics of Phase Growth in a Two-component System:
description of diffusion flux across the / interface
Todays topics
Major tasks of todays Lecture: how to derive the diffusion flux of atoms.
Once an incipient nucleus has reached its critical
Lecture 19: Eutectoid Transformation in Steels: a typical case of Cellular
Precipitation
Todays topics
Understanding of Cellular transformation (or precipitation): when applied to phase
transformation from austenite to pearlite in iron-carbon (Fe-C) steel
Lecture 14: Rate of Nucleation
Todays topics
Two energetic factors that affect nucleation rate: the activation energy barrier (G*) that
needs to be overcome to produce a critical-size nucleus, and the activation energy for an
atom to migrate across the in
Lecture 21: Types of Interfaces: coherent, semi-coherent, and incoherent
Todays topics
Basics of the three types of interfaces: coherent, semi-coherent, and incoherent, and the
major differences between them regarding the chemical and structural (strain)
Lecture 20: Eutectoid Transformation in Steels: kinetics of phase growth
Todays topics
The growth of cellular precipitates requires the portioning of solute to the tips of the
precipitates in contact with the advancing grain boundary. This can occur in on
Lecture 22: Spinodal Decomposition: Part 1: general description and
practical implications
Todays topics
basics and unique features of spinodal decomposition and its practical implications.
The relationship between the phase diagram and the free energy (G
Lecture 26: Diffusion of Ions: Part 1: basic understanding and the
derivation of diffusion flux
Todays topics
Understanding of the fundamental differences between a solution (solid or liquid) consisting of
only neutral species (atoms, molecules) and the o
Lecture 23: Spinodal Decomposition: Part 2: regarding free energy
change and interdiffusion coefficient inside the spinodal
Todays topics
Continue to understand the basic kinetics of spinodal decomposition.
Within the spinodal, d2G/dc2 < 0 and interdiffus
Lecture 27: Diffusion of Ions: Part 2: coupled diffusion of cations and
anions as described by Nernst-Planck Equation
Todays topics
Continue to understand the fundamental kinetics parameters of diffusion of ions within an
electrically neutral system (liqu
Lecture 25: Ordering Transformation
Todays topics
Understanding of the concepts of ideal solution, regular solution and real solution, and
comparison of the mixing thermodynamics between them regarding the free energy, enthalpy
and entropy change.
Underst
Lecture 24: Spinodal Decomposition: Part 3: kinetics of the
composition fluctuation
Todays topics
Diffusion kinetics of spinodal decomposition in terms of the concentration (composition)
fluctuation as a function of time: c( x, t )= Am ( , 0) exp[ R ( )t
Lecture 28: Kinetics of Oxidation of Metals: Part 1: rusting, corrosion, and
the surface protection, all about chemistry
Todays topics
Chemical processes of oxidation of metals: the role played by oxygen.
How to inhibit the oxidation depends on how effect
Lecture 29: Kinetics of Oxidation of Metals: Part 2: Wagner Parabolic
Model
Todays topics
Oxidation of metals: controlled by both the ionic diffusion (carried by M+2 and O-2) and the
electronic diffusion (carried by e- and h+).
Combination of the ionic di
Lecture 12: Heterogeneous Nucleation: a surface catalyzed process
Todays topics
What is heterogeneous nucleation? What implied in real practice of materials processing
and phase transformation?
Heterogeneous nucleation can be considered as a surface catal
Lecture 11: Homogeneous Nucleation: solid-solid phase transformation
Todays topics
Homogeneous nucleation for solid-solid phase transformation, and the major difference
compared to the liquid-solid phase transformation: the role played by the strain energ
Lecture 13: Heterogeneous Nucleation: Effects of Grain Boundaries and
Surface Defects
Todays topics
Effects of grain boundaries on solid-solid phase transformation: various types of grain
boundaries.
Defects of container wall like pinholes, cavities, crac
Lecture 2: Kinetics: as described as transformation rate between two
equilibrium states
Todays topics
As we learned in last Lecture: Rate (Kinetic factor) (Thermodynamic factor). In this
Lecture we will further describe this relationship in more analytica
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Homework for Lecture 1, 2
1. For a reaction A + B C, the Gibbs free energy change (G) is -100 kJ mol-1. Considering the
reaction temperature in the range of 300 1000 K, discuss whether the reaction is thermo controlled
or kinetic controlled, and why
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Homework for Lecture 10, 11, 12
A liquid metal ( phase) is contained in a container ( phase). Assume the melting point of the
metal is Tm = 1500 K, the molar heat of melting is HM = HL0 HS0= 16000 J/mol, and the molar
volume (for both the liquid and
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Homework for Lecture 4
Suppose there are two frogs waiting at the two ends of a feeding tube of length l. Now we feed the
frogs by putting insects into the tube from an open slot located at a position of l/3 from left, as
shown in the Figure below.
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Homework for Lecture 5
Consider a binary solution of A and B with the concentration of XA=0.20. Assuming the Henry
activity coefficient (A) of A in this binary solution is given by
ln A = 0.50 X A 2 X B .
Determine the ratio of the chemical diffusio
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Homework for Lecture 6, 5
Consider a binary solution of A and B with the concentration of XA=0.4. The free energy of this
binary solution is given by =
G G 0 + RT ( X A X B ) . Suppose the trace diffusion coefficient of A is
three times of that of B
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Homework for Lecture 3
Consider an atom diffuses in a 3D simple cubic lattice by a random walk mechanism. The atom
jumps 10-5 times per second at 300K and 104 times per second at 600K.
1). How many times the atom will jump per second at 900K?
2). Ho
Lecture 3: Diffusion: Ficks first law
Todays topics
What is diffusion? What drives diffusion to occur?
Understand why diffusion can surprisingly occur against the concentration gradient?
Learn how to deduce the Ficks first law, and understand the meaning
Lecture 2: Kinetics: as described as transformation rate between two
equilibrium states
As we learned in last Lecture: Rate (Kinetic factor) (Thermodynamic factor). In this
Lecture we will further describe this relationship in more analytical way, assumin
Lecture 1: Kinetics vs. Thermodynamics: different but related
Todays topics
The basic concepts of Kinetics and Thermodynamics, and how to understand the
difference and inter-relationship between the two when applied to chemical reactions or
materials tran