How to Calculate Diffusion Coeff
What is Diffusion Coeff?
Diffusion coefficient (D) describes rate at which atoms/molecules move through material; temperature-dependent (Arrhenius).
Formula
Calculate D = D₀ exp(-Ea/kT)
- D
- D₀ exp(-Ea/kT) — D₀ exp(-Ea/kT)
- Ea
- Ea value — Variable used in the calculation
Step-by-Step Guide
- 1Input temperature, activation energy, pre-exponential factor
- 2Calculate D = D₀ exp(-Ea/kT)
- 3Results show diffusion rate at given temp
Worked Examples
Input
Carbon in steel at 800°C
Result
D ≈ 10⁻¹² m²/s (extremely slow at room temp, faster when hot)
Common Mistakes to Avoid
- ✕Using wrong temperature (K not °C)
- ✕Neglecting Arrhenius relationship
Frequently Asked Questions
Why is diffusion important?
Controls carburizing, doping, sintering, creep; essential for heat-treatment design.
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