GTBL042-06 GTBL042-Callister-v3 September 28, 2007 21:46
2nd Revise Page
6.5 Factors That Influence Diffusion • 173
1500 1200 1000 800 600 500 400 300
Diffusion coefficient (m
2 /s)
10 –8
10 –10
10 –12
10 –14
10 –16
10 –18
10 –20
Temperature (°C)
Reciprocal temperature (1000/K)
0.5 1.0 1.5 2.0
Al in Al
Zn in Cu
Cu in Cu
C in –Fe
Fe in –Fe
C in –Fe
Fe in –Fe
Figure 6.7 Plot of
the logarithm of the
diffusion coefficient
versus the reciprocal
of absolute
temperature for
several metals. [Data
taken from E. A.
Brandes and G. B.
Brook (Editors),
Smithells Metals
Reference Book,7th
edition, Butterworth-
Heinemann, Oxford,
1992.]
Concept Check 6.1
Rank the magnitudes of the diffusion coefficients from greatest to least for the fol-
lowing systems:
NinFeat700◦C
Cr in Fe at 700◦C
NinFeat900◦C
Cr in Fe at 900◦C
Now justify this ranking. (Note: Both Fe and Cr have the BCC crystal structure, and
the atomic radii for Fe, Cr, and N are 0.124, 0.125, and 0.065 nm, respectively. You
may also want to refer to Section 5.4.)
[The answer may be found at http://www.wiley.com/college/callister (Student Companion Site).]
Concept Check 6.2
Consider the self-diffusion of two hypothetical metals A and B. On a schematic graph
of lnDversus 1/T, plot (and label) lines for both metals given thatD 0 (A)>D 0 (B)
and also thatQd(A)>Qd(B).
[The answer may be found at http://www.wiley.com/college/callister Student Companion Site).]