Consider two parallel edge dislocations of the same sign. Let θ be the angle between the line connecting the two dislocations and the direction of their Burgers vectors.
(a) Calculate the variation of the glide force and the climb force for the two dislocations as a function of the relative positions of the dislocations (i.e. as a function of θ).
(b) Which of the following configurations is more stable and why? Configuration A: The two dislocations align themselves one below the other along a direction normal to their slip planes. Configuration B: The two dislocations align themselves one beside the other along a direction normal to their slip planes.
(c) Give examples of at least two practical situations where the more stable configuration in part (b) is observed.
(d) Repeat part (a) for the situation where the two parallel edge dislocations are of opposite sign.