Atomistic studies of helium trapping and diffusion at Ni-graphene interfaces

H Huang and XX Ge and X Yu and YX Jiang and Q Peng, EUROPEAN PHYSICAL JOURNAL PLUS, 140, 497 (2025).

DOI: 10.1140/epjp/s13360-025-06447-1

The use of metal-nanocarbon interfaces to prevent the bubble-to-void transition has emerged as a novel approach for developing materials resistant to helium (He) embrittlement. However, many critical mechanisms governing He dynamics near these interfaces remain inadequately understood. Here we employed the Ni-graphene interface (NGI) as a model system to investigate He trapping and diffusion through atomistic simulations (300-1,200 K). Key findings demonstrate rapid He trapping at NGIs, with anisotropic in-plane diffusion (110\documentclass12ptminimal \usepackageamsmath \usepackagewasysym \usepackageamsfonts \usepackageamssymb \usepackageamsbsy \usepackagemathrsfs \usepackageupgreek \setlength\oddsidemargin-69pt \begindocument$$ \left \bar110 \right $$\enddocument, 112\documentclass12ptminimal \usepackageamsmath \usepackagewasysym \usepackageamsfonts \usepackageamssymb \usepackageamsbsy \usepackagemathrsfs \usepackageupgreek \setlength\oddsidemargin-69pt \begindocument$$ \left \bar1\bar12 \right $$\enddocument) exhibiting a tenfold higher diffusivity (prefactor: 6.251 x 10-2 nm2 & sdot;ps-1) and lower activation energy (0.057 eV) than pure Ni. Above 600 K, interfacial capture dominates, minimizing bulk residence. Unlike hydrogen, which forms stable C-H bonds, He migrates freely along NGIs without chemical interaction, promoting release. NGIs could suppress 3D bubble growth by redirecting He into planar pathways, aligning with observed bubble size reduction. The work contrasts He dynamics at NGIs versus grain boundaries, highlighting the superior capacity of metal- nanocarbon interfaces for He venting. These insights provide a mechanistic basis for designing helium-resistant composites, advancing strategies to mitigate embrittlement through controlled helium transport.

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