Advanced characterizations of austenitic oxide dispersion-strengthened (ODS) steels for high-temperature reactor applications

Future advanced nuclear systems involve higher operation temperatures, intenser neutron flux, and more aggressive coolants, calling for structural materials with excellent performances in multiple aspects. Embedded with densely and dispersedly distributed oxide nanoparticles that are capable of not only pinning dislocations but also trapping radiation-induced defects, oxide dispersion-strengthened (ODS) steels provide excellence in mechanical strength, creep resistance, and radiation tolerance. In order to develop ODS steels with qualifications required by advanced nuclear applications, it is important to understand the fundamental mechanisms of the enhancement of ODS steels in mechanical properties. In this dissertation, a series of austenitic ODS stainless steels were investigated by coordinated state-of-the-art techniques. A series of different precipitate phases, including multiple Y-Ti-O, Y-Al-O, and Y-Ti-Hf-O complex oxides, were observed to form during mechanical alloying. Small precipitates are likely to have coherent or cubic-on-cubic orientation relationships with the matrix, allowing the dislocation to shear through. The Orowan looping mechanism is the dominant particle-dislocation interaction mode as the temperature is low, whereas the shearing mechanism and the Hirsch mechanism are also observed. Interactions between the particles and the dislocations result in the load-partitioning phenomenon. Smaller particles were found to have the stronger loading-partitioning effect. More importantly, the load-partitioning of large size particles are marginal at elevated temperatures, while the small size particles remain sustaining higher load, explaining the excellent high temperature mechanical performance of ODS steels.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Nuclear, Plasma, Radiolgc Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Miao, Yinbin

Contributors dc:contributor

• Stubbins, James F.
• Heuser, Brent J.
• Uddin, Rizwan
• Bellon, Pascal

• Nuclear Materials
• Oxide Dispersion-Strengthened Alloys
• Austenite
• Microstructure
• Strengthening Mechanism
• Transmission Electron Microscope (TEM)
• Synchrotron Scattering
• Atom Probe Tomography

Statement dc:rights

• Copyright 2015 Yinbin Miao

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/88013

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/88013