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Chapter VII Reactivity at Dislocation….
represents their uniform speed away from the source, by simple geometry the
resulting pit will have slope,
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(7.10)
The slope tan can be measured experimentally, but more attention is
required to measure Vd.
There are many other heterogeneities at which surface “holes” may be
nucleated [27] giving rise to a finite value of surface dissolution or the polishing
rate Vp; that describes the dissolution of the surface area free from dislocation
and is directed normal to the surface.
The rate of pit deepening is given by, dD/dt = Vd - Vp, using this in the earlier
equation,
(7.11)
For etch pits formed at a constant rate, this expression can be transferred into a
linear expression,
Where, d is the measured depth of a pit after time t.
(7.12)
It is well-known that inorganic salts in solutions exist in the form of complexes
whose chemical constitution depends on the concentration of the salt in solutions
as well as on the concentration of another substance having an anion common
with the additive salt [28, 29]. The instability constant of a series of complexes of
salt, in general, regularly decreases, i.e., each successive complex is more
stable [30]. The enhanced nucleation rate along the dislocation line, due to the