In service design by simulations

Ghoniem, Nasr H.

UCLA

关键词: Forecasting;    Irradiation;    Symmetry;    36 Materials Science;    Dislocations;   

DOI  :  10.2172/841813
RP-ID  :  NONE
RP-ID  :  FG03-01ER54626
RP-ID  :  841813

美国|英语

来源: UNT Digital Library

【 摘 要 】

Irradiation of materials by energetic particles (e.g. electrons, ions and neutrons) is associated with very high internal power dissipation, which can drive the underlying nano- and microstructure far from normal equilibrium conditions. One of the most unusual responses in this connection is the ability of the material's nano- and microstructure to self-assemble in well-organized, two- and three-dimensional periodic arrangements. We reviewed and assessed experimental evidence and theoretical models pertaining to the physical understanding of nano- and microstructure self-organization under irradiation conditions. Experimental observations on the formation of self-organized defect clusters, dislocation loops, voids and bubbles were presented and critically assessed. Implantation of metals with energetic helium results in remarkable self-assembled bubble super-lattices with wavelengths (super-lattice parameters) in the range of 5-8 nm. Ion and neutron irradiation produce a wide variety of self-assembled 3-D defect walls and void lattices, with wavelengths that can be tailored in the range of 10's to 100's of nanometers. Theoretical models aimed at explaining these observations were introduced, and a consistent description of many features is outlined. The primary focus of the most recent modeling efforts, which are based on stability theory and concepts of non-linear dynamics, was to determine criteria for the evolution and spatial symmetry of self-organized microstructures. The correspondence between this theoretical framework and experimental observations was also examined, highlighting areas of agreement and pointing out unresolved questions. The main objective of this research was to develop new computational tools for in-service design and performance prediction of advanced fusion material systems by computational simulation. We also need to develop these computational tools to assist in planning and assessment of corresponding radiation experiments. In the following, we give a brief summary of the salient achievements of research supported by this grant.