1. Spinodal Decomposition Non-Classical Nucleation Theory
Microstructure Evolution
Spinodal Decomposition
Non-Classical Nucleation Theory
Byeong-Joo Lee
POSTECH - MSE

2. Background Microstructure Evolution Y C Li et al. MSMSE (2012)
Feng Yan and John Texter, 2006

3. Introduction
Refs: J.W. Cahn : Acta Met. 7, 795 (1961); J. Chem. Phys. 42, 93 (1965); Trans. AIME, 242, 166 (1968)
J.E. Hilliard, "Phase Transformations," ASM (1970)
► Historically, initiated in an effort to explain uniform distribution of CuAl2 precipitates in Al-Cu alloys.
► Consider the Gibbs energy curve and stability of matrix phase against infinitesimal fluctuation of
concentration.
○ Region I
· stable against small local fluctuation
(nothing happens)
large fluctuation → nucleation of β
small in extend, large in degree,
"Nucleation & Growth Mechanism"
○ Region II
· unstable against small local fluctuation
(decrease in total energy)
spontaneously goes to more fluctuation
small in degree, large in extend,
"Uphill Diffusion",
relatively periodic microstructure

4. Spinodal Decomposition

5. Mathematical Formulation - Thermodynamics of Spinodal Decomposition

6. Mathematical Formulation - Thermodynamics of Spinodal Decomposition

7. Mathematical Formulation - Thermodynamics of Spinodal Decomposition

8. Mathematical Formulation - Thermodynamics of Spinodal Decomposition
► existence of minimum in wave length
: for the balance between bulk energy
and interfacial energy