homework7

# homework7 - following phenomenological equations v v 1 1 µ...

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Matsc 503 Kinetics of Materials Processes Spring 2002 Problem Set #7 Due April 10 1. a. The effective charge Z* for carbon in a-Fe is -12. An electric field of 0.01V/mm is maintained in a 1mm long sample of an Fe-C alloy at a temperature of 700oC. What will be the concentration ratio between the two ends at the steady state? b. If the initial atom fraction of carbon in the alloy was 0.0005, what fraction of the length of the sample is at a concentration lower than 0.0005 at steady state, if no carbide forms? 2. Diffusion of A atoms in pure A through a vacancy mechanism can be described by the
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Unformatted text preview: following phenomenological equations v v 1 1 µ ∇ − ∇ − = T L T L J A A AA A v vv v v 1 1 ∇ − ∇ − = T L T L J A A In general the vacancies are no in equilibrium, and hence v ≠ ∇ . Using the above two equations to show that , where A A A D x D v v = A A D is the self-diffusion coefficient of A in pure A , is the vacancy diffusion coefficient in A , and x A D v v is the local mole fraction of vacancies in pure A...
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## This note was uploaded on 01/19/2010 for the course MAT SCI 503 taught by Professor Chen during the Spring '02 term at Penn State.

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