Influence of Temperature on Void Collapse in Single Crystal Nickel under Hydrostatic Compression

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Materials Science

Background:

• Void collapse is a critical phenomenon in materials under stress.
• Understanding atomistic mechanisms is key to predicting material behavior.
• Temperature effects on void collapse in metals are not fully elucidated.

Purpose of the Study:

• To investigate void collapse mechanisms in single crystal nickel under hydrostatic compression.
• To determine the influence of temperature on these atomistic collapse mechanisms.

Main Methods:

• Atomistic simulations were employed to model void collapse.
• Simulations were conducted across a range of temperatures, including low (1 K), ambient (300 K), and elevated (1200-1500 K) conditions.

Main Results:

• Dislocation loop emission and interaction is the dominant void collapse mechanism, regardless of temperature.
• Void collapse rate shows minimal temperature sensitivity until high temperatures (1200-1500 K).
• At high temperatures, vacancy diffusion aids dislocation motion, preventing strain hardening. At low/ambient temperatures, strain hardening delays collapse.
• A persistent dislocation network remains post-collapse, consistent with experimental observations.

Conclusions:

• The primary void collapse mechanism in nickel is temperature-insensitive dislocation loop activity.
• Temperature significantly influences the strain hardening behavior around collapsing voids.
• Simulated dislocation network formation aligns with experimental findings in nickel-base superalloys.