posted on 2015-01-12, 10:28authored byAndrew ArcherAndrew Archer, Morgan C. Walters, Uwe Thiele, Edgar Knobloch
Using dynamical density functional theory we calculate the speed of solidification fronts advancing
into a quenched two-dimensional model
uid of soft-core particles. We find that solidification fronts
can advance via two different mechanisms, depending on the depth of the quench. For shallow
quenches, the front propagation is via a nonlinear mechanism. For deep quenches, front propagation
is governed by a linear mechanism and in this regime we are able to determine the front speed via a
marginal stability analysis. We find that the density modulations generated behind the advancing
front have a characteristic scale that differs from the wavelength of the density modulation in
thermodynamic equilibrium, i.e., the spacing between the crystal planes in an equilibrium crystal.
This leads to the subsequent development of disorder in the solids that are formed. For the onecomponent
fluid, the particles are able to rearrange to form a well-ordered crystal, with few defects.
However, solidification fronts in a binary mixture exhibiting crystalline phases with square and
hexagonal ordering generate solids that are unable to rearrange after the passage of the solidification
front and a significant amount of disorder remains in the system.
History
School
Science
Department
Mathematical Sciences
Published in
PHYSICAL REVIEW E
Volume
90
Issue
4
Pages
? - ? (16)
Citation
ARCHER, A.J. ... et al, 2014. Solidification in soft-core fluids: disordered solids from fast solidification fronts. Physical Review E, 90 (4), 16pp.