Study of Grain Boundary and Dislocation Transmission based on a Finite-Deformation Framework with an Application to Description of Nanoindentation Tests
Final Report Abstract
Grain boundaries play an important role in the plastic deformation of metals, which is caused by dislocation. Indentations in the vicinity of grain boundaries have shown the accumulation and transmission of dislocations through grain boundaries by a so-called grain boundary popin. The aim of this proposal was to describe the complex interaction between dislocations and grain boundaries in a thermodynamically consistent gradient-crystal plasticity model taking into account large deformations. Both energetic and dissipative components were to be taken into account. The numerical simulations are experimentally supported by nanoindentation and electron microscopic investigations on bcc reference materials. The grain boundary pop-in is investigated as a function of the grain boundary misorientation. The nanoindentations were performed with different strain rates and indentation depths, taking into account the influence of the distance to the grain boundary and the relative orientation of the indenter. By means of sequential polishing and high-resolution electron backscattering investigations (ECCI), dislocation contrasts in the vicinity of grain boundaries were also mapped. This combined theoretical and experimental approach aims at a better description of the complex interaction between dislocations and grain boundaries.
Publications
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Local analysis on dislocation structure and hardening during grain boundary pop-ins in tungsten. Journal of Materials Science, 55(22), 9597-9607.
Javaid, Farhan; Xu, Yukun & Durst, Karsten
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Dislocation–grain boundary interactions: recent advances on the underlying mechanisms studied via nanoindentation testing. Journal of Materials Research, 36(12), 2545-2557.
Javaid, Farhan; Pouriayevali, Habib & Durst, Karsten
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New aspects of a single-crystal gradient plasticity model: Rate-dependency of size-dependent response. Mechanics of Materials, 185, 104771.
Pouriayevali, Habib
