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Unformatted text preview: almost pure B. How would you proceed?
A B-rich solution can be purified by first cooling it to B+L region. Let the boundaries of B
melt because that contains the highest concentration of impurities. Isolate the B-rich areas
from the liquid solution. Repeat the process for further extraction.
3. (A) Carbon diffuses through BCC iron much more rapidly than nickel does. Why?
Carbon is smaller than Ni so it diffuses more rapidly than nickel does. Carbon is an
interstitial species whereas nickel is a substitutional species.
(B) At low to moderate temperature, nickel diffuses through polycrystalline iron more
rapidly than through single crystal iron. Why?
At low temperatures, diffusivity is slower and it is generally more difficult for nickel
(substitutional species) to diffuse. However, nickel diffuses through polycrystalline more
rapidly than through a single crystal iron. A polycrystalline iron has higher defect density and
already has many vacancies present at the dislocations. The nickel is able to diffuse along the
grain boundaries of the polycr...
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This note was uploaded on 01/26/2014 for the course ENG 45 taught by Professor Stephenmorris during the Fall '12 term at University of California, Berkeley.
- Fall '12