Improving radiation resistance of metal alloys through the addition of multiple synergistic solutes: Atomistic simulations and experimental analysis
Jana, Soumyajit
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https://hdl.handle.net/2142/129997
Description
Title
Improving radiation resistance of metal alloys through the addition of multiple synergistic solutes: Atomistic simulations and experimental analysis
Author(s)
Jana, Soumyajit
Issue Date
2025-05-08
Director of Research (if dissertation) or Advisor (if thesis)
Bellon, Pascal
Averback, Robert
Doctoral Committee Chair(s)
Bellon, Pascal
Committee Member(s)
Heuser, Brent J
Trinkle, Dallas
Department of Study
Materials Science & Engineerng
Discipline
Materials Science & Engr
Degree Granting Institution
University of Illinois Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Irradiation
Metals
Simulations
Electron Microscopy.
Abstract
Many radiation damage phenomena are driven by the production and fluxes of point defects, particularly in alloys. The addition of vacancy trapping solutes is one commonly known method used to improve radiation damage tolerance. However, this method has its limits, therefore in this work a method to ameliorate these limits has been studied. A novel approach for imparting radiation resistance to dilute alloys is proposed here whereby two synergistic solute species are employed, a first one, solute B, that binds strongly to vacancies and a second one, solute C, that binds to solute B and is also a slow diffuser in solvent A. This combination results in B-C solute clusters that are immobile traps for vacancies. These traps promote point-defect recombination over irradiation doses far beyond that achievable in binary alloys, where solutes that strongly bind to vacancies are typically fast diffusers and thus quickly removed from grain interiors by radiation-induced segregation. A parametric study was performed using Atomic Kinetic Monte Carlo (KMC) simulations to study the effects of the interplay between the various thermodynamic, kinetic and microstructural parameters that govern the evolution of such ternary alloys under radiation. This was then used to identify promising ternary alloy systems. One such system was studied experimentally and the beneficial effects of the 2 synergistic solutes were then demonstrated under ion irradiation. In the KMC simulations, defect clusters were not allowed to form to simplify the analysis of the effects of the multiple solutes. Therefore finally, molecular dynamics simulations and Onsager transport theory calculations were used to expand upon the KMC simulations to study how defect clusters like divacancies affect radiation-induced segregation in the Cu-Ag system. These showed that addition of trapping solute Ag greatly reduces divacancy mobility. The fractional reduction is much greater than one obtained when monovacancies are trapped by Ag. A similar observation might be observed when a second solute is added, which has been left for future work. Thus the strategy proposed in this work of combining distinct synergistic solutes should thus be highly beneficial too when divacancies and larger vacancy clusters are present.
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