ME 2733 Chapter : Ch 7 HW Sol
Document Summary
7. 1 to provide some perspective on the dimensions of atomic defects, consider a metal specimen with a dislocation density of 105 mm 2. Suppose that all the dislocations in 1000 mm3 (1 cm3) were somehow removed and linked end to end. Now suppose that the density is increased to 109 mm 2 by cold working. The dislocation density is just the total dislocation length per unit volume of material (in this case per cubic millimeters). Thus, the total length in 1000 mm3 of material having a density of 105 mm 2 is just (105 mm 2)(1000 mm3) = 108 mm = 105 m = 62 mi. Similarly, for a dislocation density of 109 mm 2, the total length is (109 mm 2)(1000 mm3) = 1012 mm = 109 m = 6. 2 105 mi. It is possible for two screw dislocations of opposite sign to annihilate one another if their dislocation lines are parallel.
