2026-09-28 合肥物質科学研究院（HFIPS）
Ground-state structures, energetic properties, and the linear discrete model for nano-voids in iron. (Image by Li Xiaolin)
＜関連情報＞
- https://english.hf.cas.cn/nr/rn/202609/t20260928_1201551.html
- https://iopscience.iop.org/article/10.1088/1741-4326/aea7b3
- https://link.springer.com/article/10.1007/s42864-026-00402-y
ナノ結晶鉄およびタングステンにおけるヘリウム損傷の軽減に向けて：結晶学的特性によって調整された粒界の二重トラップチャネル機能に基づく戦略 Towards mitigating helium damage in nano-crystal iron and tungsten: a strategy based on the dual trap-channel functionality of grain boundaries tuned by their crystallographic character
Fangqing Qian, Xiaolin Li, He Tong, Binbin Fan, Xinru Wang, Yange Zhang, Yichun Xu, Rui Liu, Xianping Wang, Xuebang Wu,…
Nuclear Fusion Published: 28 September 2026
DOI:10.1088/1741-4326/aea7b3
Abstract
Nuclear fusion structural materials in critical components like blanket and first-wall are subjected to intense helium (He) generation, causing severe microstructural degradation that limits operational lifetime. Nanocrystalline microstructures have emerged as a promising route toward healing displacement damage. However, the theoretical feasibility of such systems to effectively capture and subsequently expel He through the grain boundary (GB) network remains uncertain, given the intrinsic diversity of GB structures and characteristics. In this work, by combining molecular statics/dynamics simulations with object kinetic Monte Carlo and rate theory, we explore the differentiated behaviors of He at GBs via screening a wide spectrum of ＜100＞and ＜110＞symmetric tilt GBs with different characteristics in α-iron (Fe) and tungsten (W). By quantifying three critical energy parameters, including He–GB binding energy, intra-GB migration energy barrier, and He–He binding energy, we demonstrate that GBs exhibit dual functional modes with respect to He accumulation: (i) fast-diffusion channels enabling rapid anisotropic pipe diffusion along specific crystallographic axes and (ii) strong-trapping sinks, characterized by low Frenkel-pair formation energy and deep binding sites that immobilize He. A quantitative relationship between GB structural descriptors (notably local free volume) and key He energetics and kinetics is also established, revealing that atomic/free volume mediates He transport along GBs, thereby clarifying the structural origin of differential He transport/retention across GB types. Furthermore, we systematically discuss the influences of irradiation/thermal defects, as well as alloying elements such as chromium, on He-related functional behaviors of GBs. Based on three governing properties: capture strength, internal diffusivity, and binding stability, this work ultimately provides theoretical foundations for designing GB character-informed He management framework. Within this framework, GB networks can be rationally tailored to simultaneously capture He and facilitate its boundary-mediated expulsion, offering a viable pathway for enhancing the radiation resistance of materials.
原子シミュレーションと進化アルゴリズムを組み合わせた手法による、体心立方金属におけるナノ空隙の構造的、エネルギー的、および運動学的結合の離散的な性質の解明 Unraveling the discrete nature of structural, energetic, and kinetic coupling of nano-voids in body-centered cubic metals through combined atomistic simulation and evolutionary algorithms
Xiao-Lin Li, Fang-Qing Qian, He Tong, Yan-Ge Zhang, Yi-Chun Xu, Xian-Ping Wang, Hong-Bo Zhou, Xue-Bang Wu, Xiang-Yan Li & Chang-Song Liu
Tungesten Published:08 September 2026
DOI:https://doi.org/10.1007/s42864-026-00402-y
Abstract
Nano-voids greatly affect the structural integrity and functional performance of nuclear metals (e.g., α-iron (Fe), tungsten (W), and molybdenum (Mo)). The vast combinatorial complexity of nano-void configurations, however, poses a significant challenge to analyzing and predicting related properties and evolutionary pathways. Here, an integrated framework combining differential evolution, atomistic simulations, and discrete modeling has been established to systematically decipher the configuration landscape of nano-voids while further revealing their discrete characteristics in energetics and kinetics. The vacancy migration energy and vacancy–vacancy binding energy (e.g., ~ 0.63 and ~ 0.24 eV for Fe) serve as a driving force for vacancy aggregation and formation into nano-voids. The framework further identifies nano-void ground-state configurations that are consistent with experimental observations. The stable structures of nano-voids evolve from small polyhedra to large faceted voids dominated by low-energy (110) and (100) surfaces, with higher geometric symmetry typically correlating with lower diffusivity. Further energetic analysis on stable nano-voids reveals discrete energy levels for vacancies near voids, each corresponding to a unique atomic coordination environment (the number of atomic bonds). Such energy–structure correlations are captured by a linear discrete model linking vacancy energetics to void geometry, which exhibits better applicability than existing theoretical frameworks such as the Wigner–Seitz (WS) model (a model founded on minimum WS cell surface area) and Wulff construction. Crucially, this discrete model reveals the intrinsic origin of the discretization behavior, i.e., the constrained range of coordination number changes during nano-void growth. Inspired by the discovered discrete energy levels, a multi-level void dissociation/trapping framework is proposed, integrating potential contributions from multiple vacancy trapping sites around a void to elucidate its stabilization mechanism. Such a mechanistic model demonstrates the pivotal role of vacancy trapping at void surfaces and subsequent diffusion in governing void morphology and the pathways of kinetic evolution. These achievements provide critical insights into the evolutionary behavior of nano-voids and advance predictive modeling of defect properties.
