For the final project, your goal is to predict the changes in plastic response of aluminum with a solid solution of magnesium using empirical potentials. You will develop data that can be used in larger-length scale modeling. You will quantify (a) changes to the dislocation core, (b) changes to the Peierls stress, and (b) changes to the cross-slip stress from the introduction of solutes. You will also consider how to include these changes in a discrete dislocation dynamics simulation.

Successful completion of this work will demonstrate competence in using MD software to analyze material plastic response, and the ability to design your own computational study.

You will produce a detailed (5–8) page report that includes an Abstract, Introduction, Methods, Results and Discussion, Conclusions, and Bibliography. This will be graded on your

- design of computational materials research project (20%),
- appropriate and competent use of computational tools (50%), and
- clarity of the report (30%)

Your report should be formatted as a single pdf document comprising
your report. You may wish to write your report in latex and convert
using `pdflatex`

, or in markdown and convert using
`pandoc report.text --to latex --out report.pdf`

.
(`module load pandoc`

and `module load texlive`

to
have the most up-to-date versions of each).

You should creating a subdirectory called
`/class/mse404pla/sp22/<your_net_id>/FinalProject`

and
copying your work into that directory by **11:59pm on 12 May 2022.
Late submissions will not be accepted; let me know in advance if you
will have difficulty with completion.**

You will need to compute the \(T=0\)
relaxed structure of a screw and edge dislocation in Al at three
different Mg concentrations: 5at.%, 10at.%, 25at.%. You should work with
the Mendelev Al-Mg EAM potential available at the NIST
repository information. In the directory
`/class/mse404pla/FinalProject`

, you will find an initial
dislocation geometry for an edge and a screw dislocation. You will also
find three files of pseudorandom sequences that you can use to construct
your solid solutions: `randnum-5.txt`

,
`randnum-10.txt`

, and `randnum-25.txt`

. These
sequences were generated by incrementing numbers starting at 1, and with
a 5, 10, or 25% probability, printing the number. For example, the start
of `randnum-25.txt`

looks like

```
3
9
10
15
16
17
22
28
35
51
```

There is also the python script `Random-sequences.py`

if
you would like to generate your own sequences. These sequences run up to
approximately \(10^6\). You will also
find an edge and screw dislocation geometry for Al.

You will need to construct relaxed edge and screw dislocation geometries containing 0, 5%, 10%, and 25% Mg to determine the changes in the dislocation core splitting, and the difference between edge and screw dislocations.

You will investigate the effect of solute on the motion of dislocations by determining the Peierls stress for edge and screw dislocations at 300K with 5%, 10%, and 25% Mg.

In addition, for the screw dislocation, you should determine the
*cross-slip stress*, which is the shear stress in the
*alternate \(\{111\}\) plane*
that causes the screw dislocation to move on that plane. For example, a
\(\frac{a}{2}[101]\) screw dislocation
can glide on either the \((\bar111)\)
plane or the \((11\bar1)\) plane. If
the dislocation core has split onto the \((\bar111)\) plane, then a shear stress
applied in the *other* plane can cause the two partial cores to
recombine and then split on the \((11\bar1)\) plane and glide: this is called
cross-slip. You should determine the stress for this process without Mg,
and then with 5%, 10%, and 25% Mg.

Conclude your assessment with a recommendation of how this materials data could be used in discrete dislocation dynamics simulations to model the effects of solutes on work-hardening.