Question

Calculate (using equation) and estimate (using figure) the following: a. Dc in FCC Fe at 912C b. Dc in BCC Fe at 912C c. DNi in FCC Fe at 912C Compare the two values for each case (one from equation and other from figure) and comment on any difference.

Answer 1

Solution:

Using equations:

A) D_C in FCC is Dc = D₀e^-Q/RT.

D₀=2.0*10^-5m²/s, R=8.314 J/(mol.K), Q=142kJ/mol (derived from experimental table given in literature):

So if we calculate Dc from above equation using derived values from experimental table we will get:

Dc = 1.1 * 10^-11 m²/s

B) D_C in BCC is  D=D₀e^-Q/RT.

D₀=22.0*10^-5m²/s, R=8.314 J/(mol.K), Q=122kJ/mol (derived from experimental table given in literature):

So if we calculate Dc from above equation using derived values from experimental table we will get:

Dc = 9.21 * 10^-10 m²/s

C) DNi in FCC Fe D=D₀e^-Q/RT.

D₀=7.7*10^-5m²/s, R=8.314 J/(mol.K), Q=280kJ/mol (derived from experimental table given in literature):

So if we calculate Dc from above equation using derived values from experimental table we will get:

Dc = 3.497 * 10^-17 m²/s

Using Figure (figure is not given in the question so i am solving related data i know for solution.)

Diffusion coefficient is inversilyproportional to density so: