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![MM 501
Ashraf Ali NED University
MODELING DIFFUSION
What causes net flow of atoms?
• Concentration Profile, C(x): [kg/m3]
• Fick's First Law:
Concentration
of Cu [kg/m 3]
Concentration
of Ni [kg/m 3]
Position, x
Cu flux Ni flux
• The steeper the concentration profile,
the greater the flux!
Adapted from
Fig. 5.2(c),
Callister 6e.](https://image.slidesharecdn.com/diffusioninsolids-lecture-1-220912150542-a40c90f6/85/Diffusion-in-Solids-Lecture-1-ppt-20-320.jpg)
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- 20. MM 501 Ashraf AliNED University MODELING DIFFUSION What causes net flow of atoms? • Concentration Profile, C(x): [kg/m3] • Fick's First Law: Concentration of Cu [kg/m 3] Concentration of Ni [kg/m 3] Position, x Cu flux Ni flux • The steeper the concentration profile, the greater the flux! Adapted from Fig. 5.2(c), Callister 6e.
- 21. MM 501 Ashraf AliNED University • Steady State: the concentration profile doesn't change with time. Steady-state diffusion • Apply Fick's First Law: • Result: the slope, dC/dx, must be constant (i.e., slope doesn't vary with position)! Jx D dC dx dC dx left dC dx right • If Jx)left = Jx)right , then From Callister 6e resource CD.
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- 23. MM 501 Ashraf AliNED University Thanks! Any questions? You can find me at ● @hamzaahmed ● hamzaahmed0696@mail.me