Details

The concentration is:

,

where is the initial concentration of the diffusing molecule in the bulk solid, is the external surface concentration of the diffusing molecule, is the distance into the bulk solid, is the diffusion coefficient characteristic of the diffusing molecule and the solid, is activation energy for diffusion in the specific system, is the gas constant, is temperature and is time.

for this Demonstration. That is, at time zero, the concentration of the diffusing species is zero everywhere except at the surface.

The following parameters are used:

carbon diffusing into iron (C into Fe):

,

copper diffusing into aluminum (Cu into Al):

,

copper diffusing into nickel (Cu into Ni):

,

.