Papers by Keyword: Solid-State Wetting

Abstract: During abnormal grain growth, a few Goss grains grow exclusively fast and consume the matrix grains. The Goss abnormally-growing grain (AGG) has peculiar features which are irregular grain boundaries and very high frequency of peninsular grains nearby the growth front of AGG and island grains trapped inside AGG. These features might provide a clue for clarifying the mechanism of Goss AGG. The experimentally-observed microstructural feature and grain boundary characterization of Goss were approached by the solid-state wetting mechanism. In this study, observing the three-dimensional wetting morphology in serial section images of Goss AGG by EBSD, we report some direct microstrucrual evidence supporting solid-state wetting mechanism for Goss AGG. The solid-state wetting mechanism for the evolution of the Goss AGG in Fe-3%Si steel explains the microstructural features evolved during secondary recrystallization, which cannot be approached by the conventional theories based on the grain boundary mobility.

Abstract: The pancake-shaped growth of Goss grains in Fe-3%Si steel is approached by solid-state wetting mechanism. The fraction of grains with Σ9 relation with Goss grains in the 0.3 mm thick specimens after primary recrystallization is higher near the surface than at the center. This result indicates that the probability of solid-state wetting is higher near the surface than at the center, leading to the pancake-shaped growth.

Abstract: Phase-field model (PFM) in multiple orientation fields was used to simulate the grain growth in three-dimensions (3-D) for isotropic and anisotropic grain boundary energy. In the simulation, the polycrystalline microstructure was described by a set of non-conserved order parameters and each order parameter describes each orientation of grains. For isotropic grain boundary energy, the simulation showed the microstructure evolution of normal grain growth. For anisotropic grain boundary energy, however, the simulation showed that certain grains which share a high fraction of low energy grain boundaries with other grains have a high probability to grow by wetting along triple junctions and can grow abnormally with a growth advantage of solid-state wetting. The PFM simulation shows the realistic microstructural evolution of island and peninsular grains during abnormal grain growth by solid-state wetting.

Abstract: Abnormal grain growth (AGG) takes place in many metallic systems especially after recrystallization of deformed polycrystals. A famous example of AGG in metallic system is the Goss texture in Fe-3%Si steel. During high temperature annealing of Fe-3%Si sheet, a few near Goss {110} <001> grains grow exclusively fast and consume the matrix grains. Therefore, the grains which have near Goss orientation have special advantage over other grains. As a new approach to the growth advantage of AGG, we suggested the solid-state wetting mechanism, where a grain wets or penetrates the grain boundary or the triple junction of its neighboring grains. The solid-state wetting mechanism for the evolution of the Goss texture in Fe-3%Si steel was studied experimentally and by phase-field model (PFM) simulation.

Abstract: Although it has been generally believed that the advantage of the grain boundary mobility induces abnormal grain growth (AGG), it is suggested that the advantage of the low grain boundary energy, which favors the growth by solid-state wetting, induces AGG. Analyses based on Monte Carlo (MC) simulation show that the approach by solid-state wetting could explain AGG much better than that by grain boundary mobility. AGG by solid-state wetting is supported not only by MC simulations but also by the experimental observation of microstructure evolution near or at the growth front of abnormally growing grain. The microstructure shows island grains and solid-state wetting along grain boundary and triple junction.