A Comparative Study on Force-Fields for Interstitial Diffusion in α-Zr and Zr Alloys

Area of Science:

• Materials Science
• Nuclear Engineering
• Computational Materials Science

Background:

• Interstitial diffusion is a key factor in radiation defect evolution within zirconium alloys.
• Understanding diffusion mechanisms is critical for predicting material behavior under irradiation.

Purpose of the Study:

• To investigate interstitial diffusion in pure alpha-zirconium (α-Zr) and its alloys with niobium (Nb) and tin (Sn) using molecular dynamics simulations.
• To analyze the impact of Nb and Sn solute atoms on diffusion anisotropy and interstitial migration barriers.

Main Methods:

• Employed molecular dynamics (MD) simulations.
• Utilized a variety of interatomic potentials for atomistic simulations.
• Simulated interstitial diffusion in pure α-Zr and Zr alloys containing 1.0 at.% Nb and 1.0 at.% Sn.

Main Results:

• Observed significant differences in diffusion anisotropy in pure Zr, attributed to variations in migration barriers across different interstitial configurations and potentials.
• Demonstrated that Nb and Sn solute atoms substantially influence diffusion anisotropy.
• Showed that solute atoms can directly participate in diffusion or modify the local chemical environment.

Conclusions:

• Accurate simulation of interstitial diffusion in Zr alloys is complex, requiring careful validation and selection of interatomic potentials.
• Solute atoms play a critical role in modifying interstitial diffusion behavior in zirconium alloys.
• Further research is needed to fully understand the effects of solute atoms on interstitial diffusion in these materials.