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oai:www.ideals.illinois.edu:2142/88138 2023-07-11 col_2142_5131 col_2142_13836 com_2142_5130 com_2142_13835 com_2142_234

Dillon, Shen Dillon, Shen Averback, Robert S. Johnson, Harley Zuo, Jian-Min Mao, Shimin 2015-09-29T20:49:26Z 2015-09-29T20:49:26Z 2017-09-30T09:15:35Z 2015-08 2015-05-27 Interfaces play an important role in material properties such as strength, cracking/fracture, work hardening, corrosion, and damage evolution under irradiation and deformation. Understanding interface-defect interactions that underlie these properties is a core motivation for studying interface phenomenon and is important in engineering design of next generation materials. Among all aspects, interface-vacancy interactions are an important building block to understand many classical structural-property relationships in polycrystals. Interfaces serve as sinks, sources or trap sites for vacancies, which facilitate creep, can drive interface migration, or serve as a vacancy-interstitial recombination site that results in an ideal lattice. This latter role provides a general approach to design radiation-tolerate materials. Previous works qualitatively investigated the ability of an interface to absorb non-equilibrium vacancies on different interfaces and grain boundaries via void denude zone (VDZ) experimental methods. However, a very limited number of quantitative studies of sink efficiency exist, and few systematic investigations comparing interfaces with different crystallography/orientation have been conducted. The importance of these phenomena and the limited experimental data in this area is the motivation of this thesis. Chapter 1 and Chapter 2 introduce the motivation and basic knowledge as well as details of the experimental techniques related to this work. Chapter 3 describes the experimental design for measuring the vacancy concentration profile in the vicinity of a Cu-Nb interface and explains how to extract the sink efficiency by comparing with a chemical rate equation. Chapter 4 is a systematic study for investigating the sink efficiency of different planar interfaces varying from semi/coherent to incoherent interfaces (Cu-Ni, Cu-V, Cu-Nb), demonstrating that sink efficiency varies as the coherency changes. Chapter 5 attempts to study the sink strength of the uniform distributed W nanoclusters/nanoprecipitates in Cu matrix produced by RT irradiation. The sink efficacy per unit area of nanoparticle-matrix interface is low relative to planar interfaces, but the high density of particles result in a similar reduction in non-equilibrium vacancy concentration in both the planar and nanoprecipitate systems. Chapter 6 describes an in-situ TEM nanocompression experiment designed to investigate the mechanical shear strength of a Cu-Nb interface as a function of irradiation dose at different temperatures. This property is used as a proxy for understanding the degree to which irradiation affects the interface structure, and suggests that steady-state behavior is established by a dose of 5 dpa. Submission published under a 24 month embargo labeled 'U of I only', the embargo will last until 2017-08-01 The student, Shimin Mao, accepted the attached license on 2015-05-26 at 19:57. The student, Shimin Mao, submitted this Dissertation for approval on 2015-05-26 at 20:15. This Dissertation was approved for publication on 2015-05-27 at 16:18. DSpace SAF Submission Ingestion Package generated from Vireo submission #8249 on 2015-09-29 at 14:58:27 Made available in DSpace on 2015-09-29T20:49:26Z (GMT). No. of bitstreams: 2 MAO-DISSERTATION-2015.pdf: 14779243 bytes, checksum: 4c188ca4a5fb5a57e754789903d13939 (MD5) LICENSE.txt: 4207 bytes, checksum: ce4c00c452bf753d206dcf407fdeabb3 (MD5) Previous issue date: 2015-05-27 Embargo set by: Seth Robbins for item 89418 Lift date: 2017-09-29T20:50:34Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system U of I Only Restriction Lifted for Item 89418 on 2017-09-30T09:15:35Z. application/pdf http://hdl.handle.net/2142/88138 en Copyright 2015 Shimin Mao nanolaminate sink efficiency interface irradiation defect mechanical property Investigating the sink efficiencies of interfaces under irradiation text text 2015-8 Materials Science & Engineerng Materials Science & Engr University of Illinois at Urbana-Champaign Dissertation Ph.D.