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| Diffusion | |||||||||||||||||
| Fixed
Surface Mass Situation
· For
a fixed mass, M, of A-atoms deposited on the surface of a B -matrix the
diffusion profile c(x,t) is:
· The "length scale" of the process is determined by time and the diffusion temperature through D(T): Length scale ~ (4D(T)t)0.5. · The graph shows the diffusion profile at constant temperature at three times: t2 >τ1 > t = 0. |
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| From: Ragone, "Thermodynamics of Materials," Wiley (1995) | |||||||||||||||||
| ·
The
area under the diffusion profile is constant and equal to the initial mass
placed on the surface.
· As the diffusion time tends to infinity, the profile tends to zero at all locations as the same initial mass is distributed over a larger volume. |
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