A sample of tungsten, W, contains an edge dislocation. W can be treated as elastically isotro pi c and the dislocation is on the specific slip plane (110), has a slip direction [-111] and a Burgers vector b=a/2[l11],
a) If the dislocation is pi nned at two points 1 micron apart so that it can be a Frank-Read source, what stress is needed to make it an active source?
b) If the dislocation was pi nned at two points 0.1 microns apart, what stress is needed to make it an active source?
c) Consider now the case where the dislocation is not pinned anywhere. However, another dislocation with the opposite Burgers vector lies on the same plane 1 micron from the first dislocation. Calculate the attraction between the two dislocation lines, (you will need to find this per unit length of dislocation line).