Dear all, as we know presence of "grain boundary" is an important item for improve of metallic models in MD simulation and it is so necessary for analysis of plastic deformation. I want to know what's driving force of formation of grain boundary in metals?
The difference in the orientation between the nucleating (and growing) grains are the reason of formation of GBs.
When the molten metal/metallic alloy crystallizes through cooling, a number of nuclei is formed as a result of a local overcooling below the liquidus. Then, a competition between the formed nuclei begins. All nuclei, whose initial size is lower than the critical one, disappear, while the enough large nuclei continue to grow until complete disappearance of a liquid phase. So, overall liquid material is "divided" by growing nuclei which become single crystals named "grains". These single crystals (which are actually the "grown nuclei") are separated by relatively thin (few atomic layers) disordered layers known as "grain boundaries". It is clear, that higher overcooling through a solidification results in higher amount of over-critical sized nuclei and, therefore, in finer grain size distribution and higher volume fraction of grain boundaries.
Thank you so much, "Akeshwar Singh Yadav" and "Alexander Katz-Demyanetz"
Dear Arash, your question is so practical for investigator, i think the answer of this question can be controversial. Anyway, in my opinion it can be related to nature of materials in solidification of them. I wish you the best.
It depends how the poly-crystal is formed and the applied mechanical treatment.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials Chemistry
- Polymer Chemistry