Nanotwinned CrN ceramics with enhanced plasticity

Area of Science:

• Materials Science
• Nanotechnology
• Ceramic Engineering

Background:

• Conventional ceramic materials exhibit high hardness but poor plasticity, limiting their applications.
• Enhancing both strength and plasticity in ceramics simultaneously is a significant materials science challenge.
• The efficacy of nanotwinning for improving plasticity in transition metal nitrides remained unexplored.

Purpose of the Study:

• To investigate the fabrication of nanotwinned chromium nitride (NT-CrN).
• To evaluate the mechanical properties, specifically strength and plasticity, of NT-CrN.
• To understand the deformation mechanisms behind the enhanced plasticity in NT-CrN.

Main Methods:

• Fabrication of NT-CrN by precisely controlling ion kinetic energy during deposition.
• Characterization of nanotwin density and twin-containing grain volume fraction.
• Mechanical testing, including compression deformation, to assess hardness and plasticity.

Main Results:

• Successfully prepared NT-CrN with a high twin density (9.0 × 10^15 m^-2) and significant twin volume fraction (52%).
• Achieved simultaneous enhancement of high hardness (>36 GPa) and room-temperature plasticity.
• Demonstrated over 40% compression deformation without brittle failure.

Conclusions:

• Nanotwinned CrN (NT-CrN) effectively enhances both strength and plasticity, overcoming conventional limitations.
• The enhanced plasticity is attributed to nanotwin boundary mechanisms enabling special slipping and energy dissipation.
• This study validates nanotwining as a viable strategy for improving the mechanical performance of transition metal nitrides.