Kinetics of disorder-to-fcc phase transition via an intermediate bcc state.
Time-resolved small-angle x-ray scattering measurements reveal that a long-lived intermediate bcc state forms when a poly(styrene-b-isoprene) diblock copolymer solution in an isoprene selective solvent is rapidly cooled from the disordered micellar fluid at high temperature to an equilibrium fcc state. The kinetics of the epitaxial growth of the [111] fcc peak from the [110] bcc peak was obtained by fitting the scattering data to a simple model of the transformation. The growth of the [111] fcc peak agrees with the Avrami model of nucleation and growth kinetics with an exponent n=1.4, as does the initial decay of the [110] bcc peak, with an exponent n=1.3. The data were also found to be in good agreement with the Cahn model of grain boundary nucleation and growth.
Liu
Yongsheng
Y
Department of Physics, Boston University, Boston, Massachusetts 02215, USA.
Nie
Huifen
H
Bansil
Rama
R
Steinhart
Milos
M
Bang
Joona
J
Lodge
Timothy P
TP