When load is applied to fcc nanograins, leading partial dislocations nucleate at grain boundary steps and propagate into the grain, leaving stacking faults behind. The extent to which these faults expand before a trailing partial is emitted generally does not equal the equilibrium separation distance of the corresponding full dislocation. Here we use a density functional theory – phase field di...

Grain boundaries arc known to exert a profound influence on the properties of polycrystalline materials at high temperature. Experimental studies on grain boundary sliding in Al bicrystals (I), or more recently in Zn bicrystals (2), show a change in the temperature dependence of the sliding rate at temperatures between 70% to 90% of the bulk melting point. The critical temperature at which a ch...

Grain boundary plane orientation is a profoundly important determinant of character in polycrystalline materials that is not well understood. This work demonstrates how boundary plane orientation fundamental zones, which capture the natural crystallographic symmetries of a grain boundary, can be used to establish structure-property relationships. Using the fundamental zone representation, trend...

Institut für Metallkunde und Metallphysik, RWTH Aachen, 52056 Aachen, Germany Carnegie Mellon University, Pittsburgh PA 15213, USA Abstract The migration of planar, symmetric tilt grain boundaries with different tilt axes was investigated. The driving force for the grain boundary migration was due to an external mechanical stress field. Low as well as high angle grain boundaries can move under ...

Four principal factors contribute to grain-boundary strengthening: (a) the grain boundaries act as barriers to plastic flow; (b) the grain boundaries act as dislocation sources; (c) elastic anisotropy causes additional stresses in grain-boundary surroundings; (d) multislip is activated in the grain-boundary regions, whereas grain interiors are initially dominated by single slip, if properly ori...

The embedded atom type otentials and static relaxation method combined with the steepest descent computational technfque have been used to simulate the grain boundary atomic structures, grain boundary energies, grain boundary cohesive energies, the distribution of electron density and stress field in the rain boundar re ion, the formation energies of vacancies and other related problems of [IOO...

We present a molecular dynamics simulation study of the migration of individual grain boundary triple junctions. The simulation cell was designed to achieve steady state migration. Observations of the triple junction angle and grain boundary profiles confirm that steady state was achieved. The static, equilibrium grain boundary triple junction angles and the dynamic triple junction angles were ...

Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. An adapted simulation method is used to systematically study grain boundary motion at velocities and driving forces...

Employing a recent modeling scheme for grain boundary sliding [Zhao et al. Adv. Eng. Mater.2017, doi:10.1002/adem.201700212], crystallographic textures were simulated for nanocrystalline fcc metals deformed in shear compression. It is shown that, as grain boundary sliding increases, the texture strength decreases while the signature of the texture type remains the same. Grain boundary sliding a...

Three-dimensional near-field high-energy X-ray diffraction microscopy has been used to observe the formation of new twinned grains in high purity Ni during annealing at 800 !C. In the fully recrystallized microstructure annealed at 800 !C, twinned grains form along triple lines. Both the grain boundary character and the grain boundary dihedral angles were measured before and after the twin form...