A comparison of the first two terms in the parenthesis in Eq. (15) defines a length
(16)
In the Cahn-Hilliard model this length scales the distance over which the concentration changes from the level of one phase to that of the other. Loosely speaking, one may call b the width of the phase boundary. The magnitude of is on the order of energy per atom at a phase boundary. Using magnitudes , and (corresponding to T = 400 K), we have b ~ 0.6 nm.
The competition between coarsening and refining (i.e., between the last two terms in Eq. 15) defines another length:
(17)
Young’s modulus of a bulk solid is about . According to Ibach, the slope of the surface stress is on the order . These magnitudes, together with , give . The following numerical simulation shows that the equilibrium phase size is on the order ~. This broadly agrees with experimentally observed phase sizes.
From Eq. (15), disregarding a dimensionless factor, we note that the diffusivity scales as . To resolve events occurring over the length scale of the phase boundary width, b, the time scale is , namely
, 
(corresponding to T = 400 K), we have b ~ 0.6 nm.
. According to Ibach, the slope of the surface stress is on the order 
, give 
. The following numerical simulation shows that the equilibrium phase size is on the order ~
. This broadly agrees with experimentally observed phase sizes.
. To resolve events occurring over the length scale of the phase boundary width, b, the time scale is 
, namely