Plasticity in brittle intermetallics enabled by framework of amorphous interfaces and preexisting dislocations

Area of Science:

• Materials Science
• Mechanical Engineering
• Nanotechnology

Background:

• Intermetallics offer high strength and melting points for structural applications.
• Inherent room temperature brittleness limits their practical use.
• Nanocrystalline (NC) materials present unique mechanical properties.

Purpose of the Study:

• To enhance both strength and plasticity of NC CoAl intermetallics.
• To overcome the brittleness limitation of intermetallics at room temperature.
• To investigate the role of amorphous interfaces and dislocations in deformation mechanisms.

Main Methods:

• Fabrication of NC CoAl with framework of amorphous interfaces (FAIs) and preexisting dislocations.
• Micropillar compression testing to evaluate mechanical properties.
• Molecular dynamics (MD) simulations to analyze dislocation behavior and deformation mechanisms.

Main Results:

• Achieved yield strength > 6 GPa, sustained work hardening to ~8.5 GPa, and plastic strain > 15%.
• FAIs accommodated plastic deformation, preventing fracture and promoting dislocation activity.
• Deformation-induced crystallization and preexisting dislocations enhanced work hardening and plasticity.

Conclusions:

• The synergistic effect of FAIs and dislocations enables significant room temperature plasticity in brittle NC CoAl.
• This strategy provides a pathway for developing ductile intermetallic alloys.
• The findings contribute to understanding deformation mechanisms in advanced structural materials.