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· The energy associated with a grain
surface depends upon the material with which the grain is in contact. Different
energies obtain for vacuum, liquid, and solid contacting phases, and also
depend on the chemistry of the phases.
· Under equilibrium conditions
(minimum free energy) an equilibrium geometric configuration is reached
at grain boundary intersections.
· The angle at the point of
intersection of the boundaries depends upon a force balance. For the case
shown in (a):
γSS
= 2 γSV
cos( ψ/2)
· In
(b) a liquid is involved and the interfacial energies change, which changes
the grain boundary junction angle: γ
SS = 2 γ
SL cos(θ/2)
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