Grain boundary triple junction dynamics: a continuum disconnection model
| Autor: | David J. Srolovitz, Yang Xiang, Luchan Zhang, Jian Han, Chaozhen Wei |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Condensed Matter - Materials Science
Materials science Condensed matter physics Continuum (topology) Applied Mathematics Triple junction Dynamics (mechanics) Materials Science (cond-mat.mtrl-sci) FOS: Physical sciences Dynamical Systems (math.DS) Computational Physics (physics.comp-ph) Microstructure 01 natural sciences 35Q74 74K30 74E15 74P10 49N10 49S05 010101 applied mathematics Grain growth FOS: Mathematics Grain boundary Crystallite 0101 mathematics Mathematics - Dynamical Systems Physics - Computational Physics |
| Popis: | The microstructure of polycrystalline materials consists of networks of grain boundaries (GBs) and triple junctions (TJs), along which three GBs meet. The evolution of such microstructures may be driven by surface tension (capillarity), applied stresses, or other means that lead to a jump in chemical potential across the GBs. Here, we develop a model for the concurrent evolution of the GB/TJ network based upon the microscopic mechanism of motion; the motion of line defects (disconnections) in the GB that have both dislocation and step character. The evolution involves thermally-activated disconnection formation/annihilation and migration of multiple disconnections modes/types. We propose this crystallography-respecting continuum model for the disconnection mechanism of GB/TJ dynamics derived with a variational approach based on the principle of maximum energy dissipation. The resultant TJ dynamics is reduced to an optimization problem with constraints that account for local microstructure geometry, conservation of Burgers vectors, and thermal-kinetic limitations on disconnection fluxes. We present analysis of and numerical simulations based upon our model to demonstrate the dependence of the GB and TJ mobilities and the TJ drag effect on the disconnection properties, and compare the predictions with molecular dynamics and experimental observations. 21 pages, 3 figures |
| Databáze: | OpenAIRE |
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