Theoretical Modeling of Lattice Strain Partitioning in Nanocrystalline FCC Metals

Chinthapenta, Viswanath R.

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Year:: 2012
Contributor:: Chinthapenta, Viswanath R (creator); Bower, Allan (Director); Kim, Kyung-Suk (Reader); Kumar, Sharvan (Reader); Brown University. ENGINEERING: Solid Mechanics (sponsor)
Genre:: theses
Subject:: nanocrystalline; lattice strain; intergranular strain; neutron diffraction; x-ray diffraction; deformation mechanisms; Neutrons--Diffraction; X-rays--Diffraction
Extent:: xxviii, 227 p.
DOI: https://doi.org/10.7301/Z0H70D4W

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Abstract:: In nanocrystalline materials it is well postulated that the grain boundary phenomena such as dislocation emission/annihilation, partial nucleation, grain-boundary (GB) sliding, and GB diffusion dominate the deformation behavior of nanocrystalline materials. State of art TEM observations Kumar et al. 2003. only provide qualitative information on deformation mechanism and hence difficult to compare with simulations. Alternative techniques like synchrotron x-ray and neutron diffraction provide quantitative assessment of deformation mechanisms by measuring the evolution of lattice and intergranular strain. Recent studies Li et al. 2008,Cheng et al. 2009 used these techniques to determine the evolution of intergranular strain. Using our continuum mechanistic modeling of nc-materials we provided insights to these neutron diffraction experiments by studying the evolution of lattice strain systematically over all the possible deformation regimes in nc materials. From our studies we observe that intergranular strain exhibits tensile shift in dislocation dominated regime which is in agreement with experiments Li et al. 2008. In GBS regime we observed intergranular strain vanishes due to fall in flow stress whereas experiments Cheng et al. 2009 show vanishing intergranular strain even in a mixed regime. Using our studies we show that the intergranular strain can be used to determine the underlying deformation mechanism including the presence of partial dislocation activity in nc-materials. Further using statistical average we quantified the deformation mechanism by measuring the lattice strain so that a better comparison between theoretical determination and experimental observations of deformation mechanisms can be made.<br/>
Notes:: Thesis (Ph.D. -- Brown University (2012)

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Chinthapenta, Viswanath R., "Theoretical Modeling of Lattice Strain Partitioning in Nanocrystalline FCC Metals" (2012). Mechanics of Solids Theses and Dissertations. Brown Digital Repository. Brown University Library. https://doi.org/10.7301/Z0H70D4W

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Theses and Dissertations for the Mechanics of Solids department.
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