Nanostructure, Plastic Deformation, and Influence of Strain Rate Concerning Ni/Al₂O₃ Interface System Using a...

Area of Science:

• Materials Science
• Computational Materials Science
• Nanomechanics

Background:

• Nickel/aluminum oxide (Ni/Al2O3) interfaces are critical in advanced materials, but their deformation mechanisms under stress are not fully understood.
• Understanding interface behavior is essential for designing materials that withstand extreme conditions, such as high strain rates.

Purpose of the Study:

• To investigate the plastic deformation mechanisms of Ni/Al2O3 interface systems under tensile loading at high strain rates.
• To explore how different interface structures influence dislocation nucleation, propagation, and overall fracture behavior.

Main Methods:

• Employed classical molecular dynamics (MD) simulations to model Ni/Al2O3 interface systems.
• Utilized a Rahman-Stillinger-Lemberg potential to accurately represent interatomic interactions between Ni, Al, and O atoms.
• Established two distinct interface structures (Type I and Type II) to analyze structure-dependent fracture behaviors.

Main Results:

• Fracture behavior strongly depends on interface structure; Type I interfaces exhibit strain hardening via Lomer-Cottrell locks.
• Type II interfaces show a 40% higher yield strength due to more stable Ni-O bonds.
• At high strain rates (>1x10^9 s^-1), Lomer-Cottrell lock formation is suppressed in Type I, and Shockley dislocation formation is delayed in Type II.

Conclusions:

• The study provides direct observation of dislocation dynamics at Ni/Al2O3 interfaces under extreme conditions.
• Interface structure critically governs plastic deformation, influencing yield strength and failure mechanisms.
• Findings enhance the understanding of Ni/Al2O3 interface behavior, aiding in the design of robust materials.