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CHAPTER 7 DISLOCATIONS AND STRENGTHENING MECHANISMS PROBLEM SOLUTIONS 7.1 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 mm3of material having a density of 105mm-2is just 105mm-2()1000 mm3()= 108mm = 105m = 62 miSimilarly, for a dislocation density of 109mm-2, the total length is 109mm-2()1000 mm3()= 1012mm = 109m = 6.2 x 105mi7.2 When the two edge dislocations become aligned, a planar region of vacancies will exist between the dislocations as: 7.3 It is possible for two screw dislocations of opposite sign to annihilate one another if their dislocation lines are parallel. This is demonstrated in the figure below. 1
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