Engineering Board Exam Reviewer · Engineering Materials · hard
The diffusion of carbon in γ-iron has D0 = 2.3 × 10-5 m2/s and Q = 148 kJ/mol. What is the diffusion coefficient at 900 ° C? (R = 8.314 J/mol· K)
- 5.91 × 10-14 m2/s
- 2.27 × 10-5 m2/s
- 5.90 × 10-12 m2/s
- 5.90 × 10-11 m2/s
Answer
C. 5.90 × 10-12 m2/s
Solution
D = D0 (-Q/RT) = 2.3 × 10-5 [-148,000/(8.314 × 1173)] = 5.90 × 10-12 m2/s. (T must be in kelvin.)
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