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

Miao, Yinbin

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https://hdl.handle.net/2142/88013 Copy

Description

Title

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

Author(s)

Miao, Yinbin

Issue Date

2015-07-10

Director of Research (if dissertation) or Advisor (if thesis)

Stubbins, James F.

Doctoral Committee Chair(s)

Stubbins, James F.

Committee Member(s)

• Heuser, Brent J.
• Uddin, Rizwan
• Bellon, Pascal

Department of Study

Nuclear, Plasma, & Rad Engr

Discipline

Nuclear, Plasma, Radiolgc Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

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

Abstract

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.

Graduation Semester

2015-8

Type of Resource

text

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

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Copyright 2015 Yinbin Miao

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