Atomistic Simulation on the Twin Boundary Migration in Mg under Shear Deformation

Area of Science:

• Materials Science
• Computational Materials Science
• Solid Mechanics

Background:

• Twinning and detwinning are fundamental deformation mechanisms in crystalline materials.
• {10 1 ¯ 2} twinning is a significant deformation mode in many materials, influencing their mechanical properties.

Purpose of the Study:

• To investigate the effects of shear direction and strain rate on {10 1 ¯ 2} twinning and detwinning.
• To elucidate the atomic-level mechanisms governing twin boundary migration.

Main Methods:

• Molecular dynamics simulations were employed to model the twinning and detwinning processes.
• Simulations were conducted under various shear directions and strain rates.

Main Results:

• Shear direction dictates whether the twin thickens or shrinks, with [ 1 ¯ 011 ] shear promoting thickening.
• The critical resolved shear stress for {10 1 ¯ 2} twin boundary migration increases with increasing strain rate.
• Atomic displacement analysis indicates that both shear and atomic shuffling contribute to twin migration.

Conclusions:

• {10 1 ¯ 2} twin migration is a complex process involving both overall atomic shear and localized atomic shuffling.
• Shear direction is the primary driver for twinning versus detwinning, while atomic shuffling refines the twin boundary structure.