Variations in grain boundary segregation for nanocrystalline stability and strength

In the last few decades, nanocrystalline metals have been of increasing interest. Their ability to show increased yield strength and uniform structure show them to be potentially useful in many applications. Additionally, nanocrystalline metals have become more easily manufactured in recent years, allowing for more testing and more use within industrial settings. However, nanocrystalline metals are still highly unstable, mainly due to temperature related growth. Grain boundary segregation is one way in which materials can keep nano length-scale grains. This process involves metal alloys that preferentially segregate the alloying material to the grain boundaries, potentially leading to Grain Boundary Embrittlement (GBE). Using an ideal work of fracture equation, [gamma] = 2[sigma]s - [sigma]g, the energy required to fracture nanocrystalline metal alloys was obtained, and predicted grain stability. Fracture toughness data is also calculated and compared. A contrast between bulk and nanocrystalline alloys is then made, showing benefits to the use of either set of materials for specific alloy functions.

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

2012

Author dc:creator

• Figueroa, Oscar, III

Advisor dc:contributor.advisor

• Christopher 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/1721.1/76179

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/76179