Journal of Nuclear Materials最新文献_第8页

Dynamic data-driven multiscale modeling for predicting the degradation of a 316L stainless steel nuclear cladding material 用于预测 316L 不锈钢核包层材料降解的动态数据驱动多尺度模型

IF 2.8 2区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Nuclear Materials

Pub Date : 2024-09-30 DOI: 10.1016/j.jnucmat.2024.155429

William E. Frazier, Yucheng Fu, Lei Li, Ram Devanathan

We have developed a long short-term memory stacked ensemble (LSTM-SE) surrogate modeling approach that can provide rapid predictions of microstructural evolution and the resultant mechanical properties of American Iron and Steel Institute (AISI) 316L series stainless steel (SS316L) fuel cladding under conditions of varying temperature and radiation dose rate. To acquire training data, we developed and implemented a kinetic Monte Carlo (KMC) model to simulate precipitation kinetics of M₂₃C₆, γ’, and G phases within SS316L cladding. Experimentally reported precipitation kinetics of SS316L in literature were linked to the kinetic parameters of the simulated precipitation in our KMC model. The model was then used to simulate microstructure evolution under synthetically generated treatments of varying temperature and radiation dose rate for periods of up to 3000 h. Changes in volume fraction, number density, and particle size of precipitates were recorded, and particle area fractions were correlated using statistical methods to develop the surrogate model. Simultaneously, the mechanical properties of the simulated microstructures were evaluated using microstructure-based finite element method (FEM) analysis to determine the elastic modulus, yield stress, ultimate tensile strength, and elongation to failure of the aged microstructures. Using this approach, our surrogate model can predict precipitation behavior within 0.25 % volume fraction and mechanical properties within 6 % relative error from the values predicted by the KMC and FEM models using 50 training simulations as input. The trained recurrent neural network-based model can return estimations of precipitation kinetics and mechanical properties ∼1000 times faster than the physics-based codes. This work demonstrates, as a proof of concept, that microstructural evolution under variable conditions can be predicted using a statistics-based model informed by a practicably obtainable dataset. The potential applications of this type of modeling framework are discussed.

我们开发了一种长短期记忆堆叠集合（LSTM-SE）代用建模方法，可以快速预测美国钢铁协会（AISI）316L 系列不锈钢（SS316L）燃料包层在不同温度和辐射剂量率条件下的微观结构演变及由此产生的机械性能。为了获取训练数据，我们开发并实施了一个动力学蒙特卡罗（KMC）模型，以模拟 SS316L 包层中 M23C6、γ'和 G 相的析出动力学。文献中报道的 SS316L 实验析出动力学与 KMC 模型中模拟析出的动力学参数相关联。记录析出物的体积分数、数量密度和颗粒大小的变化，并使用统计方法将颗粒面积分数相关联，从而建立代用模型。同时，使用基于微结构的有限元法（FEM）分析评估了模拟微结构的机械性能，以确定老化微结构的弹性模量、屈服应力、极限抗拉强度和伸长率。使用这种方法，我们的代用模型可以在 0.25 % 体积分数的范围内预测析出行为，并使用 50 次训练模拟作为输入，在 6 % 的相对误差范围内预测机械性能，而 KMC 和 FEM 模型预测的值为 0.25 %。训练有素的循环神经网络模型对沉淀动力学和机械性能的估计速度比基于物理的代码快 1000 倍。作为概念验证，这项工作证明了在可获得的数据集的指导下，使用基于统计的模型可以预测变化条件下的微观结构演变。本文讨论了这种建模框架的潜在应用。

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引用次数: 0

He irradiation resistance performance in CrNiCo, CrFeNiCo, and CrFeMnNiCo multi-principal element alloys 铬镍钴、铬铁镍钴和铬铁镍钴多主元合金的耐氦辐照性能

IF 2.8 2区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Nuclear Materials

Pub Date : 2024-09-30 DOI: 10.1016/j.jnucmat.2024.155432

Q. Xu , H.Q. Guan , S.S. Huang , Z.H. Zhong , M. Miyamoto , K. Yasunaga , A. Yabuuch

In this study, the He irradiation resistance of CrFeMnNiCo high-entropy alloy (HEA) and CrNiCo and CrFeNiCo medium-entropy alloys (MEAs), which have better mechanical properties than HEAs, was investigated. Thin-film samples of CrFeMnNiCo, CrNiCo, and CrFeNiCo were irradiated with up to 2 × 10²⁰ He/m² of 5 keV ions at 673, 773, and 873 K, respectively. In all samples, He bubble formation was observed when irradiated at 1–3 × 10¹⁹ He/m², which depended on the irradiation temperature. At low temperatures of 673 and 773 K, even when as the irradiation dose increased to 2 × 10²⁰ He/m², the differences in cavity swelling due to He bubble formation among the three alloys were not large. The relative resistance (degree) to cavity swelling for the three investigated alloys was as follows: CrNiCo MEA, CrFeMnNiCo HEA, and CrFeNiCo MEA. First-principles calculation results revealed that the formation of He-di-vacancy clusters was not possible in the CrFeNiCo MEA. This is believed to be the cause of the cavity swelling decrease in the CrFeNiCo MEA. In contrast, after 2 × 10²⁰ He/m² at 873 K, the cavity swelling of the CrNiCo and CrFeNiCo MEAs, especially CrNiCo, was approximately four times higher than that of the CrFeMnNiCo HEA. It is believed that the He irradiation resistance of the MEAs deteriorated because of element segregation owing to high–temperature irradiation.

本研究调查了铬铁镍钴高熵合金 (HEA) 以及比 HEA 具有更好机械性能的铬镍钴和铬铁镍钴中熵合金 (MEA) 的抗 He 辐照性能。分别在 673、773 和 873 K 下用高达 2 × 1020 He/m2 的 5 keV 离子辐照了铬铁镍钴、铬镍钴和铬铁镍钴薄膜样品。所有样品在 1-3 × 1019 He/m2 的辐照条件下都观察到 He 气泡的形成，这取决于辐照温度。在 673 和 773 K 的低温下，即使辐照剂量增加到 2 × 1020 He/m2，三种合金因 He 气泡形成而导致的空穴膨胀差异也不大。所研究的三种合金对空腔膨胀的相对抵抗力（程度）如下：铬镍钴 MEA、铬铁镍钴 HEA 和铬铁镍钴 MEA。第一性原理计算的结果表明，在铬镍钴 MEA 中不可能形成氦-二空位簇。这被认为是 CrFeNiCo MEA 中空穴膨胀减小的原因。相比之下，在 873 K 下 2 × 1020 He/m2 的辐照下，CrNiCo 和 CrFeNiCo MEA（尤其是 CrNiCo）的空穴膨胀率比 CrFeMnNiCo HEA 高出约四倍。据认为，由于高温辐照导致元素偏析，MEA 的耐 He 辐照性能变差。

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引用次数: 0

Controlled growth of ruthenium dioxide nanostructures in borosilicate glass melts 硼硅酸盐玻璃熔体中二氧化钌纳米结构的可控生长

IF 2.8 2区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Nuclear Materials

Pub Date : 2024-09-30 DOI: 10.1016/j.jnucmat.2024.155436

Xilei Duan , Xueyang Liu , Zhenghua Qian , Qiang Zhang , Lin Li , Kui Zhang , Yanbo Qiao

Ruthenium, a fission product generated during the fission of uranium oxide fuel in a reactor, interacts with alkali metals such as sodium in the upper layer of the cold cap, forming a sodium ruthenate intermediate (Na_xRu_yO_z), which promotes the crystallization of acicular RuO₂ within the glass melt. During vitrification, RuO₂ predominantly settles at the bottom of the melt owing to its high density and low solubility, significantly increasing both the conductivity and viscosity of the glass melt. Herein, the formation of Na_xRu_yO_z, along with the chemical reactions promoting the crystallization of RuO₂ in the waste glass, was comprehensively investigated. The results of X-ray diffraction and X-ray spectroscopy indicate that lamellar and granular Na₃RuO₄ do not form directly through the reaction between NaNO₃ and RuO₂ but rather through an intermediate stage from Na₂RuO₄. This reaction critically affects the morphology of RuO₂ within the waste glass. The uncalcined mixture of NaNO₃ and RuO₂ was found to interact with the glass melt, forming granular RuO₂ crystals, whereas the reaction of Na₃RuO₄ with the glass melt was found to lead to the formation of acicular RuO₂ crystals. The results of X-ray absorption fine structure analysis indicate that the valence state of Ru in NaRu-BSG is slightly higher than that in reference RuO₂, which was attributed to the presence of trace amounts of Na₃RuO₄ in the glass.

钌是反应堆中氧化铀燃料裂变过程中产生的裂变产物，与冷盖上层的钠等碱金属相互作用，形成钌酸钠中间体（NaxRuyOz），促进玻璃熔体中的针状 RuO2 结晶。在玻璃化过程中，由于 RuO2 密度高、溶解度低，它主要沉淀在熔体底部，从而显著增加了玻璃熔体的导电率和粘度。本文全面研究了废玻璃中 NaxRuyOz 的形成以及促进 RuO2 结晶的化学反应。X 射线衍射和 X 射线光谱分析结果表明，片状和颗粒状 Na3RuO4 并不是通过 NaNO3 和 RuO2 反应直接形成的，而是通过 Na2RuO4 的中间阶段形成的。这种反应对废玻璃中 RuO2 的形态有重要影响。研究发现，未煅烧的 NaNO3 和 RuO2 混合物与玻璃熔体相互作用，形成粒状 RuO2 晶体，而 Na3RuO4 与玻璃熔体反应则形成针状 RuO2 晶体。X 射线吸收精细结构分析结果表明，NaRu-BSG 中 Ru 的价态略高于参考 RuO2，这是因为玻璃中存在微量 Na3RuO4。

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引用次数: 0

Liquid metal embrittlement and fracture behavior of three Mo metals in liquid lead-bismuth eutectic 三种钼金属在液态铅铋共晶中的液态金属脆性和断裂行为

IF 2.8 2区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Nuclear Materials

Pub Date : 2024-09-30 DOI: 10.1016/j.jnucmat.2024.155434

Yi Zeng , Wanfeng Fu , Xiufu Yu , Jingguo Huang , Xing Gong , Yuanjun Sun , Jing Liu , Xiangdong Ding , Jun Sun

In this work, liquid metal embrittlement (LME) and the related fracture behavior of Mo, TZM and Mo-14Re were assessed in oxygen-saturated and -depleted LBE at 350°C by means of slow strain rate tensile (SSRT) tests. Neither tensile mechanical property data nor fractographic micrographs show strong evidence of LME. Nevertheless, the observation of deep secondary cracking at the fiber-like grain boundaries of Mo and Mo-14Re tested in LBE suggests occurrence of grain boundary wetting (GBW). Moreover, oxidation-assisted crack initiation and propagation were also identified. Both fracture modes may be a concern when Mo metals with a fiber-like grain structure are used in high-oxygen LBE environment.

在这项工作中，通过慢应变速率拉伸（SSRT）试验，评估了 350°C 下氧饱和和缺氧液态金属脆性（LME）以及 Mo、TZM 和 Mo-14Re 的相关断裂行为。拉伸机械性能数据和断口显微照片都没有显示出 LME 的有力证据。然而，在钼和钼-14Re 的纤维状晶界处观察到的深层二次开裂现象表明，在 LBE 中发生了晶界润湿（GBW）。此外，还发现了氧化辅助裂纹萌发和扩展。在高氧 LBE 环境中使用具有纤维状晶粒结构的钼金属时，这两种断裂模式都可能会引起关注。

引用次数: 0

Hoop tensile properties and crack propagation investigation of 2D braided SiCf/SiC composite tubes: Experiments and simulations 二维编织碳化硅/碳化硅复合材料管的环向拉伸性能和裂纹扩展研究：实验与模拟

IF 2.8 2区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Nuclear Materials

Pub Date : 2024-09-29 DOI: 10.1016/j.jnucmat.2024.155433

Mengli Xiao , Han Luo , Xiao You , Hao Qin , Chunjing Liao , Yudong Xue , Xiaowu Chen , Xiangyu Zhang , Jinshan Yang , Shaoming Dong

SiC_f/SiC composites are promising candidates for advanced pressurized water reactors (PWRs) fuel cladding materials due to their enhanced accident tolerance. Their mechanical properties are strongly influenced by the braided structure of continuous SiC fibers. This study fabricated SiC_f/SiC composite tubes with braid angles ranging from 30° to 50°, evaluating their hoop tensile properties through expansion-due-to-compression (EDC) experiments and analyzing the damage process using finite element method simulation. Results indicate that variations in braid angles significantly affect structural density, thereby impacting mechanical strength under hoop tensile stress. Increased braid angles result in smaller pore units and higher pore density, leading to local stress concentrations and varied deflections at overlapping regions. The dynamic propagation behavior of cracks was investigated through acoustic and structural nondestructive testing methods. Finite element analysis of different braid configurations highlights the pivotal role of pore units in the initiation and propagation of hoop tensile cracks. This study enhances the understanding of toughening structures in 2D braided composites and provides a theoretical basis for future accident-tolerant fuel cladding design.

SiCf/SiC 复合材料具有更强的事故耐受性，因此有望成为先进压水堆（PWR）燃料包壳材料的候选材料。连续碳化硅纤维的编织结构对其机械性能有很大影响。本研究制作了编织角为 30° 至 50° 的 SiCf/SiC 复合管，通过膨胀-直径-压缩（EDC）实验评估了其环向拉伸性能，并使用有限元法模拟分析了其损伤过程。结果表明，编织角的变化会显著影响结构密度，从而影响箍拉应力下的机械强度。编织角增大会导致孔隙单位变小、孔隙密度增大，从而导致局部应力集中，并在重叠区域产生不同的挠度。通过声学和结构无损检测方法研究了裂缝的动态扩展行为。不同编织结构的有限元分析凸显了孔隙单元在箍拉裂纹的产生和扩展过程中的关键作用。这项研究加深了人们对二维编织复合材料增韧结构的理解，并为未来耐事故燃料包层的设计提供了理论依据。

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引用次数: 0

Hot hydrogen testing of Mo30W matrix surrogate cermets Mo30W 基体代用金属陶瓷的热氢测试

IF 2.8 2区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Nuclear Materials

Pub Date : 2024-09-27 DOI: 10.1016/j.jnucmat.2024.155431

Neal D. Gaffin , Kelsa B. Palomares , Justin L. Milner , Steven J. Zinkle

High temperature hydrogen exposure is one of the most challenging material issues for nuclear thermal propulsion (NTP) fuel development. Under legacy NTP programs, ceramic-metallic (cermet) fuel forms with a refractory metal matrix and dispersed uranium dioxide (UO₂) fuel particles were developed and showed promising performance following hot hydrogen testing. However, since the conclusion of those programs, established fabrication techniques, material feedstocks, and the ability to use highly enriched have been reduced or lost all together. In this study, a cermet consisting of a solid solution alloy of molybdenum with 30 wt percent tungsten (Mo30W) was fabricated using spark plasma sintering. Fabrication process parameters were selected to optimize the cermet microstructure using lessons learned from historic NTP programs. Yttria stabilized zirconia particles (50 to 70 % volumetric loading) were used as a fuel particle surrogate. To evaluate whether as-fabricated microstructures exhibited similar resilience as legacy cermet fuels to a hot hydrogen environment, samples were exposed to hot flowing hydrogen from 1920 to 2500 °C (∼2290 to 2770 K). The cermets performed well with minimal mass loss, minor to no cracking, and good retention of internal surrogate particles. Based on these findings, recommendations for future studies with Mo30W-UO₂ cermets as an NTP fuel form are provided.

高温氢暴露是核热推进（NTP）燃料开发中最具挑战性的材料问题之一。在传统的 NTP 计划中，开发了具有难熔金属基体和分散二氧化铀 (UO2) 燃料颗粒的陶瓷金属（金属陶瓷）燃料形式，并在热氢试验后显示出良好的性能。然而，自这些项目结束以来，既有的制造技术、材料原料以及使用高浓缩铀的能力已经减少或完全丧失。本研究采用火花等离子烧结法制造了一种由钼与 30% 钨（Mo30W）的固溶体合金组成的金属陶瓷。利用从历史上的 NTP 项目中吸取的经验教训，选择了制造工艺参数来优化金属陶瓷的微观结构。钇稳定氧化锆颗粒（体积负荷为 50% 至 70%）被用作燃料颗粒替代物。为了评估制成的微结构在热氢环境中是否表现出与传统金属陶瓷燃料类似的弹性，将样品暴露在 1920 至 2500 °C （2290 至 2770 K）的热流氢中。这些金属陶瓷表现良好，质量损失极小，裂纹轻微甚至没有，内部代用颗粒保持良好。基于这些研究结果，我们对未来将 Mo30W-UO2 金属陶瓷作为 NTP 燃料形式的研究提出了建议。

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引用次数: 0

Surface morphology evolution, microstructural response and mechanical property variation of Au-ion irradiated CrNbZrMoV, TiCrZrMoV, TiNbCrMoV, TiNbZrCrV and TiNbZrMoCr high-entropy alloy coatings 金离子辐照 CrNbZrMoV、TiCrZrMoV、TiNbCrMoV、TiNbZrCrV 和 TiNbZrMoCr 高熵合金镀层的表面形貌演变、微结构响应和力学性能变化

IF 2.8 2区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Nuclear Materials

Pub Date : 2024-09-26 DOI: 10.1016/j.jnucmat.2024.155430

Jiuguo Deng , Wei Zhang , Mingyang Zhou , Ziyao Long , Xi Qiu , Yi Zhou , Jijun Yang

In this work, the CrNbZrMoV, TiCrZrMoV, TiNbCrMoV, TiNbZrCrV and TiNbZrMoCr refractory high-entropy alloy (RHEA) coatings (1.67∼2.77 μm of thickness) were prepared by magnetron sputtering. Then, 6 MeV Au-ion irradiations with 2.5 × 10¹⁵ to 1.0 × 10¹⁶ ions/cm² fluences were performed on these coatings at 473 K, and the surface morphology, microstructure and mechanical property were investigated. The peak damage of the CrNbZrMoV, TiCrZrMoV, TiNbCrMoV, TiNbZrCrV and TiNbZrMoCr coatings under 1.0 × 10¹⁶ ions/cm² fluence are 48, 48, 44, 48 and 48 dpa, respectively. The peak Au concentration of the CrNbZrMoV, TiCrZrMoV, TiNbCrMoV, TiNbZrCrV and TiNbZrMoCr coatings under 1.0 × 10¹⁶ ions/cm² fluence are 4.27 × 10³, 4.12 × 10³, 4.13 × 10³, 4.16 × 10³ and 4.37 × 10³ appm, respectively. The surface morphology of the CrNbZrMoV, TiCrZrMoV, TiNbZrCrV and TiNbZrMoCr coatings were smoothed obviously. For BCC TiNbCrMoV coating, irradiation caused the growth of the nanocrystalline. For amorphous coatings, the crystallization occurred in the CrNbZrMoV, TiCrZrMoV and TiNbZrMoCr coatings after 2.5 × 10¹⁵ fluence irradiation (≥12 dpa), while the TiNbZrCrV coating remain mainly amorphous structure after all irradiation. It was found that irradiation induced continuous crystallization occurred not only at the surface but also in the peak damage zone of the coating, and then grew inside the irradiated region. Apparent irradiation hardening was observed in all the coatings except the TiNbZrCrV coating. The structural stability of these coatings under the current irradiation condition was discussed. Preliminary study shows that the great irradiation tolerance of amorphous TiNbZrCrV coating may be related to the lowest electronegativity difference (Δχ = 0.121) and large atomic size difference (δ = 9.042 %) that stabilize the structure and inhibit atomic diffusion, respectively. These findings provide the guidance for the development of high irradiation tolerance materials for future nuclear energy applications with great structural stability.

本研究采用磁控溅射法制备了 CrNbZrMoV、TiCrZrMoV、TiNbCrMoV、TiNbZrCrV 和 TiNbZrMoCr 难熔高熵合金 (RHEA) 涂层（厚度为 1.67 ∼ 2.77 μm）。然后，在 473 K 下以 2.5 × 1015 至 1.0 × 1016 离子/cm2 的通量对这些涂层进行了 6 MeV 金离子照射，并对其表面形貌、微观结构和机械性能进行了研究。在 1.0 × 1016 离子/平方厘米的通量下，CrNbZrMoV、TiCrZrMoV、TiNbCrMoV、TiNbZrCrV 和 TiNbZrMoCr 涂层的峰值损伤分别为 48、48、44、48 和 48 dpa。在 1.0 × 1016 离子/cm2 通量下，CrNbZrMoV、TiCrZrMoV、TiNbCrMoV、TiNbZrCrV 和 TiNbZrMoCr 涂层的金浓度峰值分别为 4.27 × 103、4.12 × 103、4.13 × 103、4.16 × 103 和 4.37 × 103 appm。CrNbZrMoV、TiCrZrMoV、TiNbZrCrV 和 TiNbZrMoCr 涂层的表面形态明显平滑。对于 BCC TiNbCrMoV 涂层，辐照导致了纳米晶的生长。对于无定形涂层，CrNbZrMoV、TiCrZrMoV 和 TiNbZrMoCr 涂层在 2.5 × 1015 流强辐照（≥12 dpa）后出现结晶，而 TiNbZrCrV 涂层在所有辐照后仍以无定形结构为主。研究发现，辐照诱导的连续结晶不仅发生在涂层表面，也发生在涂层的峰值损伤区，然后在辐照区内部生长。除 TiNbZrCrV 涂层外，所有涂层都出现了明显的辐照硬化。讨论了这些涂层在当前辐照条件下的结构稳定性。初步研究表明，非晶态 TiNbZrCrV 涂层之所以具有很强的辐照耐受性，可能与最低的电负性差（Δχ = 0.121）和较大的原子尺寸差（δ = 9.042 %）有关，它们分别起到了稳定结构和抑制原子扩散的作用。这些发现为开发结构稳定的高辐照耐受性材料提供了指导，可用于未来的核能应用。

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引用次数: 0

In-situ observation of irradiation-induced amorphization on fluorapatites doped with REEs (REE = La, Nd, Sm, Tb, Er, and Lu) of various ionic radii 原位观测掺杂不同离子半径 REE（REE = La、Nd、Sm、Tb、Er 和 Lu）的氟磷灰石的辐照诱导非晶化现象

IF 2.8 2区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Nuclear Materials

Pub Date : 2024-09-26 DOI: 10.1016/j.jnucmat.2024.155425

Xiaotian Hu, Shengming Jiang, Jiemin Zhu, Jian Zhang

The immobilization of nuclear waste containing various actinides requires the actinide host phases to maintain long-term stability under alpha decay damage. In this study, the irradiation resistance to amorphization of fluorapatite compounds with the formula of Ca₉REE(PO₄)₅(SiO₄)F₂ (REE: rare earth element, REE = La, Nd, Sm, Tb, Er, and Lu) were investigated, where REEs³⁺ with decreased ionic radii were used to simulate actinides in immobilization wastes. In-situ 800 keV Kr²⁺ irradiation was performed with varying temperatures. The critical amorphization temperature,

T_{c}

, for these apatites were found to be 513.8, 503.7, 494.1, 493.7, 483.1 and 460.9 K, respectively.

T_{c}

shows a distinct decreasing trend with the decrease of ionic radii of doped REEs³⁺, indicating enhanced irradiation resistance. The selected REEs exhibited increasing electronegativity, which correlated with an increase in bonding ionic properties. This trend is unfavourable for the formation of a covalent network, thereby enhancing irradiation resistance. Besides, the decreased ionic radii of doped REEs³⁺ enhanced the migration and diffusion rates of smaller REE³⁺ after the collision cascade process. Additionally, the dopant REEs³⁺ showed a significant preference for CaⅡ sites. This preference decreased as the ionic radius of doped REE³⁺ and reduced the average ionic radius of CaⅠ sites. Consequently, the one-dimensional channel in apatite became larger, facilitating the rearrangement of F⁻ ion. This study investigated the irradiation-induced amorphization of REE-silicon doped fluorapatites and the results highlighted the importance of composition of immobilization materials on irradiation performance.

固定含有各种锕系元素的核废料需要锕系元素主相在α衰变破坏下保持长期稳定性。在这项研究中，研究了公式为 Ca9REE(PO4)5(SiO4)F2（REE：稀土元素，REE = La、Nd、Sm、Tb、Er 和 Lu）的氟磷灰石化合物的抗辐照变质能力，其中使用了离子半径减小的 REEs3+ 来模拟固定化废物中的锕系元素。在不同温度下进行了 800 keV Kr2+ 原位辐照。发现这些磷灰石的临界变质温度 Tc 分别为 513.8、503.7、494.1、493.7、483.1 和 460.9 K。随着掺杂的 REEs3+ 离子半径的减小，Tc 呈明显的下降趋势，表明抗辐照能力增强。所选 REEs 的电负性不断增加，这与成键离子特性的增加有关。这种趋势不利于共价网络的形成，从而增强了抗辐照能力。此外，掺杂 REEs3+ 的离子半径减小，提高了碰撞级联过程后较小 REE3+ 的迁移和扩散速率。此外，掺杂的 REEs3+ 对 CaⅡ 位点有明显的偏好。这种偏好随着掺杂 REE3+ 离子半径的增大而减小，并降低了 CaⅠ 位点的平均离子半径。因此，磷灰石中的一维通道变大，有利于 F 离子的重排。本研究探讨了辐照诱导的掺杂 REE-硅的氟磷灰石的非晶化过程，结果凸显了固定化材料的组成对辐照性能的重要性。

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引用次数: 0

A novel preparation of porous Li2TiO3 pebbles with a distinctive structure 具有独特结构的多孔 Li2TiO3 卵石的新型制备方法

IF 2.8 2区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Nuclear Materials

Pub Date : 2024-09-25 DOI: 10.1016/j.jnucmat.2024.155424

Yichao Gong , Zhaokun Li , Junjie Li , Jianqi Qi , Longchao Zhuo , Guojun Zhang , Tiecheng Lu

Optimization of the pore structure stands out as an effective approach for bolstering the tritium release performance of lithium-based tritium breeding ceramics, particularly when employing a high open porosity configuration. In this study, Li₂TiO₃ fibers were synthesized via the hydrothermal method, with the assistance of TiO₂-B nanowires acting as templates. Subsequently, porous Li₂TiO₃ pebbles with varying microstructures were fabricated through a combination of the wet method and a sintering process. Sintering process plays a crucial role in determining the microscopic morphology. An increase in temperature resulted in a suppression of the growth of fibrous grains and the transformation of fibrous grains into quasi-spherical grains. Moreover, a two-step sintering process was proposed as a means of improving the crush load (15.9 N vs. 22.0 N) of Li₂TiO₃ pebbles while simultaneously preserving their high porosity (24.91%). The Li₂TiO₃ pebbles, produced by the two-step sintering process, exhibited a distinctive micromorphology characterized by interconnected particles forming short rod-shaped microstructures. This distinctive micromorphology contributes to the maintenance of a high degree of open porosity (10.52%).

优化孔隙结构是提高锂基氚孕育陶瓷氚释放性能的有效方法，尤其是在采用高开放孔隙率结构时。本研究以 TiO2-B 纳米线为模板，通过水热法合成了 Li2TiO3 纤维。随后，结合湿法和烧结工艺，制备出了具有不同微观结构的多孔 Li2TiO3 卵石。烧结过程在决定微观形态方面起着至关重要的作用。温度升高会抑制纤维状晶粒的生长，并使纤维状晶粒转变为准球形晶粒。此外，还提出了一种两步烧结工艺，以提高氧化钛锂鹅卵石的压碎载荷（15.9 牛顿对 22.0 牛顿），同时保持其较高的孔隙率（24.91%）。通过两步烧结工艺制作的 Li2TiO3 卵石呈现出独特的微观形态，其特征是相互连接的颗粒形成了短棒状的微观结构。这种独特的微观形态有助于保持较高的开放孔隙率（10.52%）。

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引用次数: 0

International Simple Glass (ISG) dissolution rate in a (Si, Ca)-rich environment at 90 °C and alkaline conditions 国际简易玻璃 (ISG) 在 90 °C 和碱性条件下的富含（硅、钙）环境中的溶解率

IF 2.8 2区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Nuclear Materials

Pub Date : 2024-09-25 DOI: 10.1016/j.jnucmat.2024.155426

Benjamin Cagnon , Stéphane Gin , Martiane Cabié , Damien Daval

The dissolution of International Simple Glass (ISG) was investigated at 90 °C and alkaline conditions with various concentrations of dissolved Si and Ca to unravel the combined effects of those elements on ISG reactivity. Experiments were conducted over durations ranging from 20 days to 3 months. Through morphological, structural, and chemical characterizations, the glass dissolution rate was proven to be strongly correlated with the activity of dissolved silica in the solution. While dissolved calcium did not significantly impact the dissolution rate, precipitation of calcium silicate hydrates (CSH) during the experiments enhanced ISG dissolution rate, though to a modest extent. The 3-months experiments highlighted the strong correlation between the dissolution mechanism and the evolution of the nature of secondary phases in saturated solution. During the first 20 days and at high Si and Ca concentrations, CSH precipitated and aggregated, without preventing the passivating impact of the gel layer at the surface of the glass: the dissolution was controlled by diffusion. Then, a resumption of dissolution occurred between 19 days and 76 days, corresponding to the CSH growth, and a possible mechanistic switch to a hydrolysis-controlled reaction rate. Finally, in some experiments, a drop in pH due to carbonate precipitation was observed along with a decrease in the dissolution rate, falling back in a diffusion-limited regime. Overall, this study shows that at 90 °C, pH = 10 and concentrations of SiO₂(aq) exceeding 50 % of saturation with respect to amorphous silica, irrespective of Ca concentration but in presence of CO₂(aq), ISG exhibits a very good chemical durability.

研究了国际简易玻璃（ISG）在 90 °C 碱性条件下不同浓度的硅和钙的溶解情况，以揭示这些元素对 ISG 反应性的综合影响。实验持续时间从 20 天到 3 个月不等。通过形态、结构和化学特性分析，证明玻璃的溶解速率与溶液中溶解硅的活性密切相关。虽然溶解的钙对溶解速率没有明显影响，但实验过程中硅酸钙水合物（CSH）的沉淀提高了 ISG 的溶解速率，尽管程度不大。为期 3 个月的实验凸显了溶解机制与饱和溶液中次生相性质演变之间的密切联系。在最初的 20 天内，在硅和钙浓度较高的情况下，CSH 会析出并聚集，但不会阻止玻璃表面凝胶体层的钝化作用：溶解是由扩散控制的。然后，溶解在 19 天到 76 天之间恢复，与 CSH 的增长相对应，可能的机理转换为水解控制反应速率。最后，在一些实验中，观察到由于碳酸盐沉淀导致 pH 值下降，同时溶解速率下降，重新回到扩散受限的状态。总之，这项研究表明，在 90 °C、pH = 10 和 SiO2（aq）浓度超过无定形二氧化硅饱和度的 50%的条件下，无论钙浓度如何，只要存在 CO2（aq），ISG 就能表现出非常好的化学耐久性。

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