# Homework Help: Edge dislocation intersection from point defects

1. Oct 26, 2013

### railgundoc

1. The problem statement, all variables and given/known data

Two edge dislocations having an equal, but opposite in sign, burgers vector are gliding on parallel (111) planes in copper (FCC). Calculate the number of point defects required to bring the two dislocations together. The vertical separation between the dislocations is 1 μm, the dislocation length is 1 cm, and the a = 0.36 nm.

2. Relevant equations
I am not sure what equations I need to use...

3. The attempt at a solution
I've thought about this for a while and I think this is dislocation climb. I'm not sure whether the entire plane has to climb up or just a section or something else.

I basically figured the vertical separation has to be overcome and the lattice parameter gives the number of atoms per μm. This gives the number of defects required vertically:

1000/.36 = 2777.8 point defects.

Correct me if I'm wrong, but these dislocations are moving parallel to each other so without any other defects, they should never intersect.

I was also thinking that maybe atoms over the entire dislocation length need to move up and in that case I would have to multiply the 2777.8 by 1cm*number of atoms in that distance. (1 cm because the entire edge dislocation has to move up right?)

Any help would be appreciated.
Thanks!

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