Modeling the effect of coincidence site lattice boundaries on grain growth textures.

Abstract

The role played by coincidence site lattice (CSL) boundaries during the process of grain growth is investigated using a three-dimensional Monte Carlo model incorporating a full description of the micro- structure and the crystallographic texture. The simulations make use of the features that have been experimentally shown to characterize coincident site lattice boundaries, namely cusps in the grain-boundary energies and valleys in the mobility activation energies. These features provide a sufficiently reliable description of the dynamics of special boundaries that their role during the texturing process can be examined. In the absence of correlations between orientation and grain volume, it is found that CSL boundaries play no prominent role in influencing texture during normal grain growth. In the presence of such correlations, they play only a minor role in enhancing the growth rate of the favored texture component. During the later stage of abnormal growth, however, it is observed that the abnormally growing grains do reveal a significant increase in CSL boundaries and that this increase is most evident during the period when these grains are in their infancy, i.e., when the effect of a single CSL boundary is most strongly felt. Generally, the microstructures arising in the simulations are characterized by a high frequency of low misorientation angle boundaries (25--30 % \ensuremath{\Sigma}1), consistent with the formation of strong texture. For the purposes of applying the simulation results to the abnormal growth of Goss oriented grains in Fe--3% Si electrical steels, the starting textures were taken from relevant experimental data and the roles of the much-celebrated \ensuremath{\Sigma}5 and \ensuremath{\Sigma}9 boundaries specifically discussed.