Exceptional Microscale Plasticity in Amorphous Aluminum Oxide at Room Temperature

Area of Science:

• Materials Science
• Solid Mechanics
• Nanotechnology

Background:

• Oxide glasses are widely used but limited by brittleness.
• Amorphous aluminum oxide (a-Al2O3) is a rare exception, showing nanoscale plasticity at room temperature.

Purpose of the Study:

• To investigate the room-temperature plasticity of a-Al2O3 at the microscale and high strain rates.
• To understand the underlying deformation mechanisms.
• To assess the potential for bulk applications.

Main Methods:

• In situ micropillar compression experiments.
• Large-scale molecular dynamics simulations.

Main Results:

• a-Al2O3 micropillars deformed up to 50% strain without fracture.
• Plasticity mechanisms include viscous creep and shear band slip.
• Experimental strain rates reached 1000 s⁻¹, typical for impact loading.
• Observed plasticity volume expanded by 5 orders of magnitude.

Conclusions:

• Room-temperature plasticity of a-Al2O3 extends to the microscale and high strain rates.
• Deformation occurs via viscous creep and shear banding.
• Amorphous oxides show potential as light, high-strength, damage-tolerant engineering materials.