(a) In the manner of Equations 7.1a to 7.1c, specify the Burgers vector for the simple cub...

(a) In the manner of Equations 7.1a to 7.1c, specify the Burgers vector for the simple cubic crystal structure whose unit cell is shown in Figure 3.3. Also, simple cubic is the crystal structure for the edge dislocation of Figure 4.4, and for its motion as presented in Figure 7.1. You may also want to consult the answer to Concept Check 7.1.

(b) On the basis of Equation 7.11, formulate an expression for the magnitude of the Burgers vector, | b |, for the simple cubic crystal structure.

Figure 3.3 For the simple cubic crystal structure, (a) a hard-sphere unit cell, and (b) a reduced-sphere unit cell.

Figure 4.4 The atom positions around an edge dislocation; extra half-plane of atoms shown in perspective.

(Adapted from A. G. Guy, Essentials of Materials Science, McGraw-Hill Book Company, New York, NY, 1976, p.)

Figure 7.1 Atomic rearrangements that accompany the motion of an edge dislocation as it moves in response to an applied shear stress. (a) The extra half-plane of atoms is labeled A. (b) The dislocation moves one atomic distance to the right as A links up to the lower portion of plane B; in the process, the upper portion of B becomes the extra half-plane. (c) A step forms on the surface of the crystal as the extra half-plane exits. (Adapted from A. G. Guy, Essentials of Materials Science, McGraw-Hill Book Company, New York, 1976, p.)

 (7.1)

 (7.11)

Concept Check 7.1Which of the following is the slip system for the simple cubic crystal structure? Why?

(Note: A unit cell for the simple cubic crystal structure is shown in Figure 3.3.)

[The answer may be found at www.wiley.com/college/callister (Student Companion Site).]