The shape evolution and migration of <100> and <111> tilt grain boundaries with rotation angles θ in the range between 6° and 24° were investigated in situ in a scanning electron microscope at elevated temperatures. The results revealed that boundaries with misorientation θ<15° did not attain a continuously curved shape in the entire temperature range up to the melting point and, thus, did not move under a capillary driving force. Instead, they remained straight or formed several facets which were inclined to the initial boundary orientation. Molecular statics simulations suggest that the observed behavior of low-angle boundaries is due to the anisotropy of grain boundary energy with respect to boundary inclination. This anisotropy diminishes with increasing misorientation angle, and high-angle boundaries assume a continuously curved shape and move steadily under the curvature driving force.

This paper proposes an approach to determine the smallest volume fraction of second-phase particles that is necessary to arrest grain growth and to stabilize grain microstructure.

This chapter contains sections titled: Abstract Introduction Casting and Solidification The Casting Alloys Casting Simulation of the Casting Process Thermodynamic Description of the Model Alloy Simulation of Grain Nucleation and Growth Using a Multiphase Flow and Solidification Model Simulation of Phase Fractions, Dendrite Arm Spacing, and Concentration Profiles Using a Microsegregation Model Homogenization Homogenization of Alloy AA3104 Simulation Methods DICTRA Calculations ClaNG Model Experimental Procedure Comparison between Experimental and Simulation Results Primary Phases Solute Concentrations Dispersoid Precipitation Hot and Cold Rolling Flow Stress Modeling Texture Simulation Recrystallization Cup Drawing Anisotropy Update Results Conclusions and Outlook References

Activation energies for solute diffusion along dislocations are difficult to measure experimentally. The aim of this work is to provide insight into pipe diffusion with the help of atomistic simulations. The distribution of vacancy formation energy and the activation energy for copper migration are determined in the core of an edge dislocation in aluminum. The Dimer method is used to find activation energies for vacancy migration. The activated region around the dislocation where a very high diffusivity is observed and the activation energy for copper diffusion associated with this region are interpreted with regard to the contribution of the dislocation and the contribution of the alloying.