Masoud Rahbar Niazi^1*, W. A Curtin^1,2*

1 Laboratory for Multiscale Mechanics Modeling, Institute of Mechanical Engineering École Polytechnique Fédérale de Lausanne Lausanne CH-1015, Switzerland

2 School of Engineering, Brown University, Providence, RI 02912, USA

* Corresponding authors emails: masoud.rahbarniazi@epfl.ch, william.curtin@epfl.ch

DOI10.24435/materialscloud:1e-c7 [version v1]

Publication date: Jan 09, 2024

How to cite this record

Masoud Rahbar Niazi, W. A Curtin, Solute strengthening of prism edge dislocations in Mg alloys, Materials Cloud Archive 2024.6 (2024), https://doi.org/10.24435/materialscloud:1e-c7

Description

The poor ductility of hcp Mg is attributed to the low activity of non-basal slip systems and so activation of prismatic slip can aid ductility in rolled sheets by providing three additional <a> Burgers vector slip systems. Experimental studies show that dilute additions of alloying elements such as Zn and Al leads to softening of prismatic slip at low temperatures but strengthening at higher temperatures. Here, the role of solute strengthening of prismatic edge dislocations is investigated as a possible explanation for the higher-T strengthening. Mg-Zn is studied using first-principles inputs in a parameter-free solute strengthening theory. First-principles DFT is necessary to accurately assess the strong solute chemical interaction energies in the core of the compact edge dislocation. Such calculations are subtle due to motion of the dislocation in the presence of the solute, and methods to obtain reliable results with acceptable computational cost are discussed. While interaction energies of Zn in the prism edge core can be quite large (+/- 0.34 eV), the edge solute strengthening of prismatic slip in dilute Mg-Zn remains well below experiments at high temperatures. However, the large difference (0.68 eV) in Zn/dislocation interaction energies across the core of the edge dislocation suggests strengthening by dynamic strain aging as an explanation for the higher-T strengthening.

Materials Cloud sections using this data

Files

File name	Size	Description
dislocation_pure.zip MD5md5:3f6bd66e694873cf7aa42c9caf7f718e	1.6 MiB	DFT calculation for prism edge dislocation in pure Mg
Zn_edge dislocation dft.zip MD5md5:1c329788f553818f5db30342cf01e245	419.5 MiB	DFT calculations for Zn/edge-dislocation interaction energies
README.txt MD5md5:01fa1d83e75a3bce8ba1ddd0b630b6f2	852 Bytes	Explains the contents of the files

License

Files and data are licensed under the terms of the following license: Creative Commons Attribution 4.0 International.
Metadata, except for email addresses, are licensed under the Creative Commons Attribution Share-Alike 4.0 International license.

External references

Keywords

Mg-Zn edge solute-strengthening prismatic slip DFT solute/dislocation interaction energy MARVEL