Interaction of dislocations with carbon-decorated dislocation loops in bcc Fe: an atomistic study

Area of Science:

• Materials Science
• Nuclear Engineering
• Computational Physics

Background:

• Ferritic Fe-based alloys' properties are sensitive to dissolved carbon.
• Interstitial carbon interacts strongly with defects and dislocations.
• Radiation defect accumulation and mechanical property changes are carbon-dependent.

Purpose of the Study:

• Investigate how interstitial carbon atoms influence small dislocation loops.
• Understand the effect of carbon-vacancy complexes on dislocation loop interactions.
• Analyze the role of carbon decoration on radiation damage and plastic deformation.

Main Methods:

• Molecular dynamics (MD) simulations were employed.
• Simulations focused on interactions between 1/2<111> dislocation loops and dislocations in bcc Fe.
• Loop sizes of 1 nm (invisible) and 3.5 nm (visible) were simulated, considering carbon-vacancy complexes.

Main Results:

• Carbon decoration strongly suppresses the drag of dislocation loops by dislocations.
• Invisible, carbon-decorated loops act as obstacles at least twice as strong as undecorated ones.
• Visible loops also showed additional strengthening due to carbon decoration, impacting radiation hardening.

Conclusions:

• Carbon decoration/segregation at dislocation loops affects radiation damage accumulation.
• Post-irradiation plastic deformation mechanisms are altered by carbon decoration.
• Undetectable, carbon-decorated dislocation loops contribute to radiation hardening.