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Title: Modeling investigation of the stability and irradiation-induced evolution of nanoscale precipitates in advanced structural materials

Materials used in extremely hostile environment such as nuclear reactors are subject to a high flux of neutron irradiation, and thus vast concentrations of vacancy and interstitial point defects are produced because of collisions of energetic neutrons with host lattice atoms. The fate of these defects depends on various reaction mechanisms which occur immediately following the displacement cascade evolution and during the longer-time kinetically dominated evolution such as annihilation, recombination, clustering or trapping at sinks of vacancies, interstitials and their clusters. The long-range diffusional transport and evolution of point defects and self-defect clusters drive a microstructural and microchemical evolution that are known to produce degradation of mechanical properties including the creep rate, yield strength, ductility, or fracture toughness, and correspondingly affect material serviceability and lifetimes in nuclear applications. Therefore, a detailed understanding of microstructural evolution in materials at different time and length scales is of significant importance. The primary objective of this work is to utilize a hierarchical computational modeling approach i) to evaluate the potential for nanoscale precipitates to enhance point defect recombination rates and thereby the self-healing ability of advanced structural materials, and ii) to evaluate the stability and irradiation-induced evolution of such nanoscale precipitates resulting from enhancedmore » point defect transport to and annihilation at precipitate interfaces. This project will utilize, and as necessary develop, computational materials modeling techniques within a hierarchical computational modeling approach, principally including molecular dynamics, kinetic Monte Carlo and spatially-dependent cluster dynamics modeling, to identify and understand the most important physical processes relevant to promoting the “selfhealing” or radiation resistance in advanced materials containing nanoscale precipitates. In particular, the interfacial structure of embedded nanoscale precipitates will be evaluated by electronic- and atomic-scale modeling methods, and the efficiency of the validated interfaces for trapping point defects will next be evaluated by atomic-scale modeling (e.g., determining the sink strength of the precipitates), addressing key questions related to the optimal interface characteristics to attract point defects and enhance their recombination. Kinetic models will also be developed to simulate microstructural evolution of the nanoscale features and irradiation produced defect clusters, and compared with observed microstructural changes.« less
Authors:
 [1]
  1. Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
OSTI Identifier:
1178434
Report Number(s):
DOE/NEUP--10-906
10-906; TRN: US1600517
DOE Contract Number:
AC07-05ID14517
Resource Type:
Technical Report
Research Org:
Univ. of Tennessee, Knoxville, TN (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE). Nuclear Energy University Program (NEUP)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; VACANCIES; INTERSTITIALS; PRECIPITATION; EVOLUTION; ANNIHILATION; NANOSTRUCTURES; IRRADIATION; NEUTRONS; MICROSTRUCTURE; COMPUTERIZED SIMULATION; INTERFACES; MOLECULAR DYNAMICS METHOD; MONTE CARLO METHOD; RECOMBINATION; STABILITY; DIFFUSION; TRAPPING; EFFICIENCY; REACTOR MATERIALS; PHYSICAL RADIATION EFFECTS; TIME DEPENDENCE