Why grain growth is not curvature flow

Area of Science:

• Materials Science
• Condensed Matter Physics
• Crystallography

Background:

• Grain growth in polycrystals is traditionally modeled as a capillarity-driven process governed by mean curvature flow.
• Experimental and simulation evidence increasingly challenges this simplistic view of grain boundary (GB) migration.

Purpose of the Study:

• To investigate the fundamental mechanisms driving grain growth beyond classical capillarity-driven models.
• To demonstrate the significant role of shear deformation coupled with grain boundary motion in microstructure evolution.

Main Methods:

• Large-scale microstructure evolution simulations were employed.
• Simulations incorporated the fundamental, crystallography-respecting microscopic mechanism of grain boundary migration.
• The study focused on analyzing deviations from mean curvature flow.

Main Results:

• The failure of classical mean curvature flow in describing grain growth is primarily attributed to shear coupling during grain boundary migration.
• Simulations revealed deviations consistent with recent experimental observations across various materials.
• The research highlights the necessity of incorporating mechanical effects for accurate microstructure evolution predictions.

Conclusions:

• Shear coupling is a critical factor in grain boundary migration, necessitating a revision of traditional grain growth models.
• Accurate prediction of microstructure evolution requires integrating mechanical effects alongside capillarity-driven processes.
• This work provides a framework for understanding and modeling complex grain growth phenomena.