ABSTRACT
Ostwald ripening
) or the lamellae thickness in
colonies
(see
discontinuous coarsening
).
particle drag
Drag force
exerted by
dispersed particles
or
pores
. If the particles of the volume fraction
f
and the mean diameter
d
are arranged at the
grain boundaries
as, e.g., pores in
crystalline
ceramics
, the drag force is:
∆
g
=
a
γ
f
/
d
where
a
is a coefficient, and
γ
is the
grain-boundary energy
(it is supposed equal to the energy of the
phase boundary
between the particles
and matrix). Pores inhibit grain boundary migration if they are relatively large and immobile; small pores can migrate together with the boundary and affect its motion to a lesser extent than immobile pores. In the case of uniformly distributed particles, the drag force is referred to as
Zener drag
and is proportional to
f/d
.
