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posted by  Budhockey26 on 11/4/2009 7:54:24 PM  |  status: Closed  |  Earned Karma: 35

Materials

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Question Details:
The diffusion coefficients (D) for carbon in nickel are 5.5 x 10-14m2 /s at 600oC and 3.9 x 10-13 at 700oC. (a) Determine the values of Do and Qd. (b) What is the magnitude of D at 850oC?
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posted by harry9(MNK) on 11/5/2009 1:21:27 AM  |  status: Live
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Response Details:
D = Do * e(-Qd/RT)

so, 5.5*10-14/3.9*10-13 = e(-Qd/RT1+Qd/RT2)

0.141026 = e(-Qd/8.31*873+Qd/8.31*973)

-1.9588=Qd*-1.41668*10-5

Qd = 138266.9 J/mol

Do = 1.04144*10-5 m2/s

(b) at T = 1123 K

D = 1.04144*10-5*e(-138266.9/(8.31*1123))

D = 3.8285*10-12 m2/s
harry
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