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HW6 ENME382 S10 Section0201

HW6 ENME382 S10 Section0201 - 3 How far into the sheet from...

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ENME 382 Section 0201 Homework 6 Due in class: 2 Apr. 2010 1a) How can you distinguish between steady state and non-steady state diffusion? b) What is the driving force for steady state diffusion? c) When would you expect a vacancy diffusion mechanism? d) When would you expect an interstitial diffusion mechanism? e) What is the difference between self diffusion and interdiffusion. 2a) A sheet of steel 1.5 mm thick has nitrogen atmospheres on both sides at 1200°C and is permitted to achieve a steady-state diffusion condition. The diffusion coefficient for nitrogen in steel at this temperature is 6x10 -11 m 2 /s and the diffusion flux is found to be 1.2 x 10 -7 kg/m 2 s. Also, it is known that the concentration of nitrogen in the steel on the high pressure side is 4 kg/m
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Unformatted text preview: 3 . How far into the sheet from this high-pressure side will the concentration be 2.0 kg/m 3 ? Assume a linear concentration profile. b) By what mechanism will the nitrogen diffuse? Why? 3. The diffusion coefficients for carbon in nickel are given at two temperatures: T (°C) D (m 2 /s) 600 5.5 × 10 –14 700 3.9 × 10 –13 (a) Determine the values of D and Q d . (b) What is the magnitude of D at 850°C? Study questions: Note: These are additional questions to help guide you as you read and study. I will not collect or grade study questions. Also, we will not provide solutions although we will try to work out a solution if you ask me to solve a specific problem. Chapter 5: Callister: 5.18, 6.2, 6.3, 6.6...
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