Crystallographically consistent percolation theory for grain boundary networks

Grain boundaries are known to play a role in many important material properties including creep resistance, ductility and cracking resistance. Although the structure and properties of individual boundaries are important, the overall behavior of the material is determined largely by the connectivity of grain boundaries in the microstructure. Grain boundary networks may be studied in the framework of percolation theory by classifying boundaries as special or general to the property of interest. In standard percolation theory, boundaries are randomly assigned as special or general; however, this approach is invalid in realistic grain boundary networks due to the requirement for crystallographic consistency around any closed circuit in the microstructure. The goal of this work is to understand the effects of these local constraints on the connectivity and percolation behavior of crystallographically consistent grain boundary networks. Using computer simulations and analytical models, the behavior of crystallographically consistent networks is compared to that of randomly-assembled networks at several different length scales. At the most local level, triple junctions and quadruple nodes are found to be preferentially coordinated by special and general boundaries, leading to nonrandom network topologies that are quantified using topological parameters.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Materials Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Frary, Megan

Advisor dc:contributor.advisor

• Christopher A. Schuh.

• Materials Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/33402

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/33402