Dissociated prismatic loop punching by bubble growth in FCC metals

Area of Science:

• Materials Science
• Atomistic Modeling
• Solid-State Physics

Background:

• Bubble generation significantly degrades material performance.
• Experimental observations of bubble superlattices exist but lack mechanistic understanding.
• Athermal bubble growth is a critical phenomenon in materials under irradiation.

Purpose of the Study:

• To elucidate the atomistic mechanisms of bubble growth in copper (Cu) under helium (He) implantation.
• To bridge the gap between experimental observations and theoretical understanding of bubble evolution.
• To investigate the role of dislocations in helium bubble growth and superlattice formation.

Main Methods:

• Atomistic modeling using molecular dynamics simulations.
• Analysis of dislocation network nucleation and evolution.
• Correlation with experimental data and nanoindentation test results.

Main Results:

• Bubble growth is accommodated by dislocation network nucleation, followed by dissociated prismatic dislocation loop (DPDL) formation and emission.
• DPDLs are capable of collecting He atoms, potentially facilitating self-organized bubble superlattice formation.
• Pressurized bubbles adopt an imperfect octahedral shape, consistent with experimental findings.
• DPDL punching mechanism is proposed to be applicable to other face-centered cubic (FCC) metals.

Conclusions:

• The study provides a detailed atomistic understanding of athermal bubble growth in Cu.
• The findings integrate atomistic simulations with experimental observations, enhancing mechanistic insights.
• The identified mechanisms, particularly DPDL punching, have broader implications for helium bubble behavior in FCC metals.