Biomedical Engineering Reference
In-Depth Information
Fig. 2.10
(
a
)
cs
(˛)plotin
two dimensions. (
b
)
Illustration of
m
as a function
of crystallographic
orientation. The structural
match between nucleus and
substrate and the
corresponding
m
. Reprinted
with permission from ref. [
8
].
Copyright (2004) Springer
In general, as
f
(
m
,
R
0
) varies from 0 to 1 (or
m
from 1 to
1), the interfacial
structure correlation between the nucleating phase and the substrate changes from a
completely correlated and ordered state to a completely uncorrelated and disordered
state.
Due to the anisotropy of the crystalline phase, the deviations from the optimal
structural match position toward the secondary optimal structural match (the second
lowest
cs
('), Fig.
2.10
b) will adopt discrete values rather than exhibit a continuous
change, which is the second lowest minimum of
cs
in the orientation of
f
h
0
k
0
l
0
g
.
A similar principle holds for further deviations. Therefore, the deviations from the
optimal structural match reflect the transition of
m
from
m
1
to lower and discrete
values
m
D
m
2
,
m
3
,etc.(cf.Fig.
2.10
b).
In the case of nucleation promotion, the adsorption of additives on foreign
particles will improve the interaction and/or the structural match between the
substrate (foreign particles) and the nucleating phase. This will then result in
m
!
1
