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Description
Title: | Novel precipitate structures in alloys under irradiation |
Author(s): | Shu, Shipeng |
Director of Research: | Bellon, Pascal |
Doctoral Committee Chair(s): | Bellon, Pascal |
Doctoral Committee Member(s): | Averback, Robert S; Trinkle, Dallas R; Zhang, Yang |
Department / Program: | Materials Science & Engineerng |
Discipline: | Materials Science & Engineering |
Degree Granting Institution: | University of Illinois at Urbana-Champaign |
Degree: | Ph.D. |
Genre: | Dissertation |
Subject(s): | self-organization
irradiation |
Abstract: | We investigate the fundamentals of precipitate stability under energetic particle irradiation, towards the goal of better controlling the microstructures of driven alloys. First we focus on an irradiation-induced precipitatewithin- precipitate structure, which is referred to as “cherry-pit” structure. We show by computer simulation and analytical modeling that the formation of cherry-pit structure is a special instance of compositional patterning, and that the conditions for compositional patterning and the formation of cherry-pit structures are related, but different from each other. Then we develop a new kinetic Monte Carlo model, which includes the generation, recombination, and sink elimination of irradiation-induced point defects, as well as ballistic mixing. With this tool we explore the possibility of using point-defect sinks to alter the temperature range where compositional patterns are stable. This novel approach for optimizing radiation-resistant materials is then tested experimentally using a Cu-Ag-W model alloy. Lastly we show that the addition of a high density of W nanoparticles dramatically alters the coarsening behavior of precipitate-hardened Cu-Ag alloys. First, the nanoparticles suppress precipitate growth, but far more surprisingly they induce non-equilibrium Ag wetting layers on grain boundaries. This observation is explained using kinetic Monte Carlo simulations, which show that caging of Ag precipitates by the W nanoparticles suppresses their growth and drives the formation of the wetting layers. |
Issue Date: | 2015-08-27 |
Type: | Text |
URI: | http://hdl.handle.net/2142/88942 |
Rights Information: | Copyright 2015 Shipeng Shu |
Date Available in IDEALS: | 2016-03-02 |
Date Deposited: | 2015-12 |
This item appears in the following Collection(s)
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Dissertations and Theses - Materials Science and Engineering
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Graduate Dissertations and Theses at Illinois
Graduate Theses and Dissertations at Illinois