On the Migration of a High‐Angle Grain Boundary—Effect of Shear Stress and Energy Jump‐Driving Force on Micro‐Bicrystals

Abstract

Grain boundary (GB) migration plays a crucial role in the microstructural evolution of polycrystalline materials, particularly in fine-grained materials. This migration can be driven by shear forces or by an energy jump across a GB. Interestingly, GB migration processes during cyclic loading deformations have been observed to be fully reversible. This study focuses on understanding the impact and importance of shear driving forces, the free energy difference across a GB, and lattice dislocations on GB migration. These factors are key points for gaining deeper insights into the underlying mechanisms of GB migration. In this work, GB migration in cyclic loading deformations is demonstrated, and it is emphasized that it clearly depends on both the shear driving forces (attributed to the motion of disconnections) and the energy differential across the GB. Two cyclic micro-experimental methods, accompanied by analytical and numerical simulations, have been employed to investigate the role of shear stresses and energy jump-driving forces in GB migration. This investigation provides clear experimental evidence that GB migration, in particular for a high-angle GB, is dependent on both stress and energy driving forces.