Relative grain boundary energy as a function of misorientation angle was measured in a cube-oriented, 120 mu m-thick Al foil and in a < 111 > fiber-textured, 1.7 mu m-thick Al film using a multiscale analysis of the grain boundary dihedral angles. For the Al foil, the energies of low-angle boundaries increased with misorientation angle, in good agreement with the Read-Shockley model. For the Al film, two energy minima were observed for high-angle boundaries. Grain growth was studied in 25 and 100 mn-thick films that were annealed at 400 degrees C for a series of times in the range of 0.5 to 10 h. For the 100 nm-thick film, grains approximately doubled their size (equivalent circular diameter) before grain growth stagnated. The steady-state distributions of reduced grain area for two-dimensional, Monte Carlo Potts and partial differential equation based simulations showed excellent agreement with each other, even when anisotropic boundary energies were used. However, the simulated distributions had fewer small grains than the experimental distributions.

The effect of a 1.5T, 15T and 30T magnetic field on texture evolution in Fe-1\%Si was investigated by annealing samples for 1 hour at 787 degrees C, (27 degrees above the Curie temperature, T-c = 760 degrees C). The intensity of the Goss texture component increased with increasing field strength accompanied by a drastic increase in grain size.

The effect of a 1.5T, 15T and 30T magnetic field on texture evolution in Fe-1\%Si was investigated by annealing samples for 1 hour at 787 degrees C, (27 degrees above the Curie temperature, T-c = 760 degrees C). The intensity of the Goss texture component increased with increasing field strength accompanied by a drastic increase in grain size.

The average orientation of an electron backscatter diffraction (EBSD) map is calculated by the quaternion method and is compared with nonlinear solving by the Hill Climbing and Barton-Davison methods. An automated EBSD system acquires orientations on a regular grid of pixels based on indexation of Kikuchi patterns and the orientation is described by one of the crystal symmetry-related equivalents; In order to calculate the quaternion average, it is necessary to make a cloud for a set of pixels in a grain. A cloud consists of the representative orientations with small misorientation between each and every pair of points. The position criterion says that two adjacent pixels have a smaller misorientation than with all others. With this, the proper equivalent orientation, or representative orientation, for the cloud, can be selected from among all the crystal symmetry-related equivalents. The orientation average is the quaternion summation divided by its norm. The instant average or cumulative average is useful for dealing with polycrystalline grains or orientation discontinuity and is also useful for selection of the proper orientation of EBSD map with large scattering. The quaternion, Hill Climbing, and Barton-Dawson nonlinear methods are tested with a Gaussian distribution around the ideal texture component, Brass 110 < 112 >. The accuracy of the three results is similar but the nonlinear methods are associated with longer computation times than the quaternion method. The quaternion method is adapted for characterization of a partially-recrystallized interstitial-free (IF) steel and randomly distributed Brass, S, and cube texture components according to several different orientation spreads.

The effects of anisotropic grain boundary properties on the evolution of boundary plane distributions were studied using three-dimensional finite element simulations of normal grain growth. The distribution of boundary planes was affected by energy anisotropy whereas no effect was observed for comparatively larger mobility anisotropy. (c) 2005

A Monte Carlo simulation technique was employed to model certain aspects of recrystallization in steels, namely the formation of elongated grain shapes, the control of grain size by particle pinning, and the dependence of texture evolution on particle density and stored energy. The first set of simulations investigated the growth of a single nucleus in a bi- or tri-crystal matrix and focused on grain boundary character. When low angle boundaries are present between the matrix and the nucleus, the recrystallizing grain grew abnormally into the neighboring matrix grains. However, if the matrix grains had a large difference in stored energy at a boundary, the movement of the grain boundary was hindered; the recrystallized grain cannot grow into the matrix but instead grew along the boundary. Hence elongated grains could be obtained with a special orientation relationship at the boundary without dispersed fine particles. Particle pinning was examined in the second set of simulations. Particles were found to retard recrystallization only for low stored energies; the largest grain was obtained at the critical condition for recrystallization. Thus if nucleation sites are restricted to low densities, larger elongated grains are obtained. Both particle pinning and stored energy levels influenced texture evolution during recrystallization. (c) 2005 Elsevier B.V. All rights reserved.

A theory for abnormal grain growth (AGG) in polycrystalline materials is revisited and extended in order to predict AGG in textured polycrystals. The motivation for the work is to improve our understanding of the origins of the Goss texture component, 110< 001 >, during annealing of Fe-Si sheet. Since the AGG phenomenon in grain-oriented electrical steels is known to be dependent on the presence of a dispersion of fine second phase particles, the grain boundary properties are treated as representative of the homogenized behavior of the material, and not necessarily the properties that would be measured directly. The predictions of AGG are presented in the form of maps in Euler space, showing which texture components are most likely to grow abnormally. For different models of grain boundary properties applied to a theoretically derived texture, different sets of texture components are predicted to grow; neither model, however, predicts growth of the Goss component.

A theory for abnormal grain growth (AGG) in polycrystalline materials is revisited and extended in order to predict AGG in textured polycrystals. The motivation for the work is to improve our understanding of the origins of the Goss texture component, 110< 001 >, during annealing of Fe-Si sheet. Since the AGG phenomenon in grain-oriented electrical steels is known to be dependent on the presence of a dispersion of fine second phase particles, the grain boundary properties are treated as representative of the homogenized behavior of the material, and not necessarily the properties that would be measured directly. The predictions of AGG are presented in the form of maps in Euler space, showing which texture components are most likely to grow abnormally. For different models of grain boundary properties applied to a theoretically derived texture, different sets of texture components are predicted to grow; neither model, however, predicts growth of the Goss component.

The role of orientation pinning by neighboring grains oil migrating boundaries in a statically recrystallized oxygen-free high-conductivity (OFHC copper was investigated. Two specimens of heavily drawn OFHC copper wires deformed to true strains of 2.31 and 3.56 were, annealed at 170degreesC and local orientations were mapped by means of the automated electron backscattered diffraction technique. Inverse pole figures, misorientation distribution functions. and grain boundary misorientations were calculated from local orientation data. In spite of annealing, the nucrostrucrure of the low-strain specimen was characterized by elongated grains, similar to the as-deformed structure, whereas the microstructure of the high-strain specimen showed a high fraction of well-defined recrystallized grains. The recrystallized grains consisted of type A grains. which mostly grew laterally with hkl< 100 > orientations and type B grains, which generally grew axially with hkl < 100 > orientations. Type A grains were larger and of higher frequency than type B grains. The large size of Type A grains was attributed to the high frequency of the mobile boundaries with misorientations in the 40 to 50 deg range. Boundaries that were rnisoriented at 60 deg < 111 > (Sigma3) were found to exert the greatest pinning effect on the groqing grains. This caused recrystallized grains to grow either laterally or axially, and sometime led to branching. A detailed analysis of the influence of the next neighbor misorientations in the perimeter of the recrystallized grains is presented.