(a) Write a simple computer program that gives the shear stress of a screw dislocation as a function of the perpendicular distance from the dislocation (see Eq. 4.8). Assuming that the shear modulus is 86 GPa, and the Burgers vector is 0.248 nm, use the program to obtain the shear stress at the following values of r: 50, 100, 150, and 200 nm, respectively. Plot the resulting ? versus r data, and with the aid of this curve, determine the distance from the dislocation where ? is 4000 psi, the shear stress at which an iron crystal will begin to undergo slip.

Question

(b) To how many Burgers vectors does this distance correspond?

Answer 1