91Ó°ÊÓ

For an FCC single crystal, would you expect th surface energy for a (100) plane to be greater less than that for a (111) plane? Why? (Note: Yo may want to consult the solution to Problem \(3.6\) at the end of Chapter 3.).

For a BCC single crystal, would you expect the surface energy for a (100) plane to be greater or less than that for a (110) plane? Why? (Note: You may want to consult the solution to Problem \(3.61\) at the end of Chapter 3.)

(a) For a given material, would you expect the surface energy to be greater than, the same as, or less than the grain boundary energy? Why? (b) The grain boundary energy of a small-angle grain boundary is less than for a high-angle one. Why is this so?

(a) Briefly describe a twin and a twin boundary. (b) Cite the difference between mechanical and

For each of the following stacking sequences found in FCC metals, cite the type of planar defect that exists: (a)...ABCABCBACBA... (b) ... ABCABCBCABC... Copy the stacking sequences and indicate the position(s) of planar defect(s) with a vertical dashed line.

For an ASTM grain size of 6, approximately how many grains would there be per square inch under each of the following conditions? (a) At a magnification of \(100 \times\) (b) Without any magnification

Determine the ASTM grain-size number if 30 grains per square inch are measured at a magnification of \(250 \times\).

Determine the ASTM grain-size number if 25 grains per square inch are measured at a magnification of \(75 \times\).

Following is a schematic micrograph that represents the microstructure of some hypothetical metal.Determine the following: (a) Mean intercept length (b) ASTM grain-size number, \(G\)