Edge dislocation intersection from point defects

In summary: Expert SummarizerIn summary, the problem at hand involves two edge dislocations in copper (FCC) with equal, but opposite, burgers vectors moving on parallel (111) planes. The goal is to calculate the number of point defects necessary to bring the two dislocations together, given a vertical separation of 1 μm and a dislocation length of 1 cm. The approach is to use dislocation climb to overcome the vertical separation, taking into account the length of the dislocation and the number of atoms in that length. The calculation results in a total of 2777.8 point defects needed. This is an example of dislocation climb, where the dislocations move parallel to each other.
  • #1
railgundoc
2
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Homework Statement



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.

Homework Equations


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

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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  • #2


Thank you for your post. Your approach to this problem is correct. In order to bring the two dislocations together, there needs to be a vertical movement of atoms to overcome the separation between them.

Your calculation of 2777.8 point defects vertically is correct. However, you also need to take into account the length of the dislocation. As you correctly mentioned, the entire edge dislocation needs to move up, so you would need to multiply the number of point defects by the length of the dislocation (1 cm) and the number of atoms in that length. This would give you the total number of point defects required to bring the two dislocations together.

I would also like to mention that this is indeed an example of dislocation climb, where the dislocations are moving parallel to each other on the (111) planes.

I hope this helps and please let me know if you have any further questions. Best of luck with your calculations!


 

1. What is an edge dislocation?

An edge dislocation is a type of crystal defect in which an extra half-plane of atoms is inserted into a crystal lattice, causing a discontinuity or misalignment in the atomic arrangement. This creates a line defect, or "edge," where the extra plane of atoms meets the rest of the crystal structure.

2. How do edge dislocations intersect with point defects?

Edge dislocations can intersect with point defects, such as vacancies or interstitial atoms, in the crystal lattice. This interaction can lead to changes in the crystal's mechanical properties, such as increased strength or ductility.

3. What is the significance of edge dislocation intersection from point defects in materials science?

The intersection of edge dislocations with point defects is an important aspect of materials science, as it can greatly influence the mechanical properties of a material. By studying and understanding these interactions, scientists can design and engineer materials with desired properties for specific applications.

4. How are edge dislocation intersections from point defects observed and analyzed?

Edge dislocation intersections from point defects can be observed and analyzed using various techniques, such as transmission electron microscopy (TEM) and X-ray diffraction (XRD). These methods allow scientists to visualize and measure the structural changes caused by the intersection of these defects.

5. Can edge dislocation intersection from point defects be controlled or manipulated?

While edge dislocation intersection from point defects can occur naturally, they can also be controlled and manipulated through various processes, such as heat treatment or mechanical deformation. This allows for the creation of materials with specific properties for different applications.

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