Substantial planar plastic anisotropy in inorganic Mg₃Bi₂ single crystals

Area of Science:

• Materials Science
• Solid Mechanics
• Crystallography

Background:

• Understanding plastic deformation mechanisms is key for designing functional materials.
• Magnesium bismuthate (Mg3Bi2) compounds exhibit notable room-temperature ductility, but the underlying mechanisms are not well understood.
• Plastic anisotropy in materials influences their mechanical performance and applications.

Purpose of the Study:

• To investigate the origin of plastic anisotropy in single-crystalline Mg3Bi2.
• To determine the role of slip systems in the plastic behavior of Mg3Bi2.
• To establish a fundamental understanding of Mg3Bi2 plasticity for materials design.

Main Methods:

• Micropillar compression testing was employed to probe mechanical properties.
• Machine learning was used to develop an interatomic potential for Mg3Bi2.
• Molecular dynamics simulations were performed to analyze deformation mechanisms.

Main Results:

• A significant in-plane plastic anisotropy was observed in single-crystalline Mg3Bi2.
• Plastic deformability is critically dependent on the activation of single versus double slip systems.
• Pyramidal dislocations were identified as crucial for Mg3Bi2 plasticity.

Conclusions:

• Crystallographic orientation-dependent activation of competing slip systems is the fundamental origin of plastic anisotropy in Mg3Bi2.
• Activation of double slip systems leads to superior plastic deformability.
• This research provides insights into the microscopic mechanisms governing Mg3Bi2 plasticity, aiding in the design of advanced materials.