Pub Date : 2024-10-10DOI: 10.1016/j.jnucmat.2024.155447
Zixie Wang , Jie Pan , Ao Liu , Li Zhang , Zeyuan Sun , Zhen Wang , Jun Li , Xueshan Xiao
A novel lightweight thermal neutron absorbing Al-xGd alloy (x = 2.5, 5, and 10 wt.%) with tunable mechanical properties was fabricated by induction melting followed by a rolling process and an annealing treatment. During solidification, the Al3Gd phase predominantly formed and was distributed along grain boundaries. Cold rolling crushed and redistributed the Al3Gd phase throughout the matrix. Furthermore, the large deformation imposed on the material during cold rolling enhanced the work hardening effect and promoted dynamic recrystallization. The load transfer strengthening effect was influenced by the size, volume fraction, and distribution of the second phase. The spheroidization of the second phase increased rapidly and then remained stable during 5000 h long-term aging at 400 °C. The thermal neutron absorbing performance of the Al-5Gd alloy is comparable to the 30 %B4C/Al composite evaluated by Monte Carlo simulations. Furthermore, Al-5Gd alloy exhibited higher plasticity (>20 %). This novel Al-xGd alloy is a promising candidate for future lightweight thermal-neutron-absorbing materials.
{"title":"Microstructure and properties controlling of Al-xGd alloys for thermal neutron absorbing","authors":"Zixie Wang , Jie Pan , Ao Liu , Li Zhang , Zeyuan Sun , Zhen Wang , Jun Li , Xueshan Xiao","doi":"10.1016/j.jnucmat.2024.155447","DOIUrl":"10.1016/j.jnucmat.2024.155447","url":null,"abstract":"<div><div>A novel lightweight thermal neutron absorbing Al-<em>x</em>Gd alloy (<em>x</em> = 2.5, 5, and 10 wt.%) with tunable mechanical properties was fabricated by induction melting followed by a rolling process and an annealing treatment. During solidification, the Al<sub>3</sub>Gd phase predominantly formed and was distributed along grain boundaries. Cold rolling crushed and redistributed the Al<sub>3</sub>Gd phase throughout the matrix. Furthermore, the large deformation imposed on the material during cold rolling enhanced the work hardening effect and promoted dynamic recrystallization. The load transfer strengthening effect was influenced by the size, volume fraction, and distribution of the second phase. The spheroidization of the second phase increased rapidly and then remained stable during 5000 h long-term aging at 400 °C. The thermal neutron absorbing performance of the Al-5Gd alloy is comparable to the 30 %B<sub>4</sub>C/Al composite evaluated by Monte Carlo simulations. Furthermore, Al-5Gd alloy exhibited higher plasticity (>20 %). This novel Al-<em>x</em>Gd alloy is a promising candidate for future lightweight thermal-neutron-absorbing materials.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"603 ","pages":"Article 155447"},"PeriodicalIF":2.8,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142537322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-10DOI: 10.1016/j.jnucmat.2024.155451
Le Zhang , Bo Sun , Qili Zhang , Haifeng Liu , Haifeng Song
Within DFT+U-D3 scheme, we systematically investigate the major steps of CO2 reaction on Pu-oxide surfaces, including CO2 adsorption, dissociation and CO releasing. On intact Pu-oxide surfaces, the chemical adsorption of CO2 needs to be activated, while the dissociation is unlikely to happen. Interestingly, both steps can be notably promoted when Pu-oxide surfaces are covered with *H or *OH from dissociated H2O, which is fully consistent with the experimental findings that moisture can boosting CO2 adsorption on PuO2 surface. Specifically, the polarons induced by *H or *OH show strong couplings with CO2, which first activate the barrier-less chemisorption of CO2 and then promote the dissociation of CO2 by weaken the CO bond. Furthermore, we find that the oxidation state of Pu in its oxides determines the tendency of CO releasing step, which is endothermic and exothermic on PuO2 and α-Pu2O3 surfaces, respectively. Thus, we predict the reaction of CO2 on Pu-oxide surface is not impossible, especially when PuO2 is reducing to α-Pu2O3 during the long-term storage. This work reveals the reaction mechanism and possible reactive pathway of CO2 on Pu-oxides, which provides a significant step forward in the understanding of the surface reactions of actinide oxides.
在 DFT+U-D3 方案中，我们系统地研究了二氧化碳在氧化钚表面反应的主要步骤，包括二氧化碳吸附、解离和二氧化碳释放。在完整的氧化钚表面，二氧化碳的化学吸附需要激活，而解离则不太可能发生。有趣的是，当氧化钚表面被*H或解离出的H2O产生的*OH覆盖时，这两个步骤都能得到明显的促进，这与实验结果完全一致，即水分能促进二氧化碳在氧化钚表面的吸附。具体来说，*H 或*OH 诱导的极子与 CO2 发生强耦合，首先激活 CO2 的无阻化学吸附，然后通过削弱 CO 键促进 CO2 的解离。此外，我们还发现，钚在其氧化物中的氧化态决定了 CO 释放步骤的趋势，在 PuO2 和 α-Pu2O3 表面，CO 释放步骤分别为内热和放热。因此，我们预测二氧化碳在钚氧化物表面的反应并非不可能，尤其是当钚氧化物在长期储存过程中还原为α-钚氧化物时。这项工作揭示了二氧化碳在钚氧化物上的反应机理和可能的反应途径，为了解锕系元素氧化物的表面反应迈出了重要一步。
{"title":"The reaction mechanism of CO2 on PuO2 and α-Pu2O3 surfaces","authors":"Le Zhang , Bo Sun , Qili Zhang , Haifeng Liu , Haifeng Song","doi":"10.1016/j.jnucmat.2024.155451","DOIUrl":"10.1016/j.jnucmat.2024.155451","url":null,"abstract":"<div><div>Within DFT+<em>U</em>-D3 scheme, we systematically investigate the major steps of CO<sub>2</sub> reaction on Pu-oxide surfaces, including CO<sub>2</sub> adsorption, dissociation and CO releasing. On intact Pu-oxide surfaces, the chemical adsorption of CO<sub>2</sub> needs to be activated, while the dissociation is unlikely to happen. Interestingly, both steps can be notably promoted when Pu-oxide surfaces are covered with *H or *OH from dissociated H<sub>2</sub>O, which is fully consistent with the experimental findings that moisture can boosting CO<sub>2</sub> adsorption on PuO<sub>2</sub> surface. Specifically, the polarons induced by *H or *OH show strong couplings with CO<sub>2</sub>, which first activate the barrier-less chemisorption of CO<sub>2</sub> and then promote the dissociation of CO<sub>2</sub> by weaken the C<img>O bond. Furthermore, we find that the oxidation state of Pu in its oxides determines the tendency of CO releasing step, which is endothermic and exothermic on PuO<sub>2</sub> and α-Pu<sub>2</sub>O<sub>3</sub> surfaces, respectively. Thus, we predict the reaction of CO<sub>2</sub> on Pu-oxide surface is not impossible, especially when PuO<sub>2</sub> is reducing to α-Pu<sub>2</sub>O<sub>3</sub> during the long-term storage. This work reveals the reaction mechanism and possible reactive pathway of CO<sub>2</sub> on Pu-oxides, which provides a significant step forward in the understanding of the surface reactions of actinide oxides.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"603 ","pages":"Article 155451"},"PeriodicalIF":2.8,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142440983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-10DOI: 10.1016/j.jnucmat.2024.155453
Yi Liu , Yusheng Zhang , Lianwen Wang , Jinping Wu , Xin Jia , Jianping Xu , Zhonglin Shen , Naizhi Liu , Chengze Liu
The constant stress tensile deformation behavior of commercial Zr702, used in spent fuel reprocessing industry, was investigated in 108 °C/200 MPa nitric acid solutions and non-corrosive silicone oil. Microscopic characterization of surface as well as cross-section of deformed Zr702 was carried out. In silicone oil, there were minimal cracks observed on the sample's surface. However, a significant number of cracks appeared on the sample's surface in nitric acid solutions. In nitric acid solutions, at the interface between the oxide layer and the matrix, cracks occurred, extended, the oxide film fractured, cracks further expanded, and the stress concentration at the cracks tip led to the formation of new cracks. This cyclic process resulted in the strength of the material decreasing and accelerated failure.
{"title":"Accelerated failure behavior of Zr702 in boiling nitric acid solutions under constant stress loading","authors":"Yi Liu , Yusheng Zhang , Lianwen Wang , Jinping Wu , Xin Jia , Jianping Xu , Zhonglin Shen , Naizhi Liu , Chengze Liu","doi":"10.1016/j.jnucmat.2024.155453","DOIUrl":"10.1016/j.jnucmat.2024.155453","url":null,"abstract":"<div><div>The constant stress tensile deformation behavior of commercial Zr702, used in spent fuel reprocessing industry, was investigated in 108 °C/200 MPa nitric acid solutions and non-corrosive silicone oil. Microscopic characterization of surface as well as cross-section of deformed Zr702 was carried out. In silicone oil, there were minimal cracks observed on the sample's surface. However, a significant number of cracks appeared on the sample's surface in nitric acid solutions. In nitric acid solutions, at the interface between the oxide layer and the matrix, cracks occurred, extended, the oxide film fractured, cracks further expanded, and the stress concentration at the cracks tip led to the formation of new cracks. This cyclic process resulted in the strength of the material decreasing and accelerated failure.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"603 ","pages":"Article 155453"},"PeriodicalIF":2.8,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142440985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-10DOI: 10.1016/j.jnucmat.2024.155442
Yingchong Xu , Hongxian Xie , Guang-Hong Lu
Experimental observations reveal that disclinated non-equilibrium grain boundaries (GBs) exist extensively in polycrystalline metals; however, the interaction between these GBs and irradiation-induced point defects is rarely reported. In the present work, Molecular statics simulation was used to evaluate the capacity of disclinated non-equilibrium GBs to accommodate point defects in tungsten. Simulation results showed that disclinated non-equilibrium GBs are more efficient sinks for point defects than their equilibrium counterparts because of long-range stress field around them. Continuous segregation of point defects will change the structure of the disclinated non-equilibrium GBs and leads to the GBs tending to relax to equilibrium state. According to theoretical calculation, the disclinated non-equilibrium GBs can absorb a large number of point defects before transforming into equilibrium state; therefore, disclinated non-equilibrium GBs have very strong capacity to accommodate point defects and can be used as strong defect sinks for developing radiation resistance materials.
{"title":"The capacity of disclinated non-equilibrium GBs to accommodate point defects in tungsten","authors":"Yingchong Xu , Hongxian Xie , Guang-Hong Lu","doi":"10.1016/j.jnucmat.2024.155442","DOIUrl":"10.1016/j.jnucmat.2024.155442","url":null,"abstract":"<div><div>Experimental observations reveal that disclinated non-equilibrium grain boundaries (GBs) exist extensively in polycrystalline metals; however, the interaction between these GBs and irradiation-induced point defects is rarely reported. In the present work, Molecular statics simulation was used to evaluate the capacity of disclinated non-equilibrium GBs to accommodate point defects in tungsten. Simulation results showed that disclinated non-equilibrium GBs are more efficient sinks for point defects than their equilibrium counterparts because of long-range stress field around them. Continuous segregation of point defects will change the structure of the disclinated non-equilibrium GBs and leads to the GBs tending to relax to equilibrium state. According to theoretical calculation, the disclinated non-equilibrium GBs can absorb a large number of point defects before transforming into equilibrium state; therefore, disclinated non-equilibrium GBs have very strong capacity to accommodate point defects and can be used as strong defect sinks for developing radiation resistance materials.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"603 ","pages":"Article 155442"},"PeriodicalIF":2.8,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142440984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-10DOI: 10.1016/j.jnucmat.2024.155455
Jinfan Chen, Tao Tang
Density functional theory calculations coupled with thermodynamic analysis have been performed to investigate the reactions of hydrogen and impurity gases including O2, CO2, CO, N2 on α-U(001) and α-UH3(001) surfaces. Binding strength of adsorbates on α-UH3 is calculated to be weaker than α-U, suggesting enhanced poisoning-resistant properties of U-hydride compared to its metallic state. Surface phase diagrams of U under binary H2-O2, H2-N2 and H2-CO gaseous environments show that while N and C elements prefer to stay in their hydrogenated states on the hydride surface, isolated O atoms favorably interact with both α-U(001) and α-UH3(001), indicating the heavily poisoning effect of impurities containing oxygen. Global optimization of partially oxidized α-U(001) slabs induces surface geometry reconstruction and the activity of oxidized surfaces toward hydrogen adsorption can be linearly correlated with local electronic and atomic properties of the adsorption site.
通过密度泛函理论计算和热力学分析，研究了氢气和杂质气体（包括 O2、CO2、CO 和 N2）在 α-U(001) 和 α-UH3(001) 表面上的反应。根据计算，α-UH3 上吸附剂的结合强度比 α-U 弱，这表明 U-hydride 的抗中毒特性比金属态更强。在二元 H2-O2、H2-N2 和 H2-CO 气体环境下的 U 表面相图显示，N 和 C 元素更喜欢保持氢化物表面的氢化状态，而孤立的 O 原子则与α-U(001) 和 α-UH3(001) 发生有利的相互作用，这表明含氧杂质具有严重的中毒效应。部分氧化的 α-U(001)板的全局优化引起了表面几何重构，氧化表面的氢吸附活性与吸附位点的局部电子和原子特性成线性关系。
{"title":"First-principles thermodynamical modeling of molecular reactions on α-U(001) and α-UH3(001) surfaces and their influence on hydrogen activation","authors":"Jinfan Chen, Tao Tang","doi":"10.1016/j.jnucmat.2024.155455","DOIUrl":"10.1016/j.jnucmat.2024.155455","url":null,"abstract":"<div><div>Density functional theory calculations coupled with thermodynamic analysis have been performed to investigate the reactions of hydrogen and impurity gases including O<sub>2</sub>, CO<sub>2</sub>, CO, N<sub>2</sub> on α-U(001) and α-UH<sub>3</sub>(001) surfaces. Binding strength of adsorbates on α-UH<sub>3</sub> is calculated to be weaker than α-U, suggesting enhanced poisoning-resistant properties of U-hydride compared to its metallic state. Surface phase diagrams of U under binary H<sub>2</sub>-O<sub>2</sub>, H<sub>2</sub>-N<sub>2</sub> and H<sub>2</sub>-CO gaseous environments show that while N and C elements prefer to stay in their hydrogenated states on the hydride surface, isolated O atoms favorably interact with both α-U(001) and α-UH<sub>3</sub>(001), indicating the heavily poisoning effect of impurities containing oxygen. Global optimization of partially oxidized α-U(001) slabs induces surface geometry reconstruction and the activity of oxidized surfaces toward hydrogen adsorption can be linearly correlated with local electronic and atomic properties of the adsorption site.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"603 ","pages":"Article 155455"},"PeriodicalIF":2.8,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142537321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-10DOI: 10.1016/j.jnucmat.2024.155454
Zihao Lin , Ziyu Zhang , Jibo Tan , Xinqiang Wu
The effects of coolant pH on the crud deposition behavior on the Zr alloy and the FeCrAl fuel cladding tubes under subcooled nucleate boiling condition were investigated. With the increase of coolant pH, the coverage rate and thickness of crud on the surfaces of both the Zr alloy and the FeCrAl fuel cladding tubes showed a decreasing trend. The solubility of crud compositions was reduced due to the increase of coolant pH, which resulted in the inhibition of the crud deposition process caused by SNB condition. Consequently, the elevated coolant pH value reduced the amount of crud on the surface of the fuel cladding tube.
{"title":"Effects of coolant pH on crud deposition behavior on fuel cladding tube under subcooled nucleate boiling condition in high temperature pressurized water","authors":"Zihao Lin , Ziyu Zhang , Jibo Tan , Xinqiang Wu","doi":"10.1016/j.jnucmat.2024.155454","DOIUrl":"10.1016/j.jnucmat.2024.155454","url":null,"abstract":"<div><div>The effects of coolant pH on the crud deposition behavior on the Zr alloy and the FeCrAl fuel cladding tubes under subcooled nucleate boiling condition were investigated. With the increase of coolant pH, the coverage rate and thickness of crud on the surfaces of both the Zr alloy and the FeCrAl fuel cladding tubes showed a decreasing trend. The solubility of crud compositions was reduced due to the increase of coolant pH, which resulted in the inhibition of the crud deposition process caused by SNB condition. Consequently, the elevated coolant pH value reduced the amount of crud on the surface of the fuel cladding tube.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"603 ","pages":"Article 155454"},"PeriodicalIF":2.8,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142440986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-09DOI: 10.1016/j.jnucmat.2024.155450
Xian-Wei Zheng , Li Jiang , Kai Wang , Qing-Chun Zhu , Jian-Ping Liang , Chao-Wen Li , Zhi-Jun Li , Guang-Dong Che
The corrosion and Te embrittlement behaviors of Ni-Mo-Cr-Nb based alloy in the Te-containing molten salts have been investigated as compared with the standard GH3535 alloy. Nb is more resistant to molten salt dissolution than Cr due to the less negative Gibbs formation energy of fluoride and the more sluggish lattice diffusion. Furthermore, it was verified the Ni-Mo-Cr-Nb alloy possesses the obvious better Te embrittlement resistance than GH3535 alloy. Our results confirmed that Ni-Mo-Cr-Nb alloy is one of the most promising candidate materials in molten salt reactors.
与标准 GH3535 合金相比，研究了 Ni-Mo-Cr-Nb 基合金在含 Te 熔盐中的腐蚀和 Te 脆化行为。由于氟化物的负吉布斯形成能较低，且晶格扩散速度较慢，因此铌比铬更耐熔盐溶解。此外，还验证了 Ni-Mo-Cr-Nb 合金的抗脆性明显优于 GH3535 合金。我们的研究结果证实，Ni-Mo-Cr-Nb 合金是熔盐反应堆中最有前途的候选材料之一。
{"title":"Corrosion and Te embrittlement behaviors of Ni-Mo-Cr-Nb alloy in Te-containing molten salts","authors":"Xian-Wei Zheng , Li Jiang , Kai Wang , Qing-Chun Zhu , Jian-Ping Liang , Chao-Wen Li , Zhi-Jun Li , Guang-Dong Che","doi":"10.1016/j.jnucmat.2024.155450","DOIUrl":"10.1016/j.jnucmat.2024.155450","url":null,"abstract":"<div><div>The corrosion and Te embrittlement behaviors of Ni-Mo-Cr-Nb based alloy in the Te-containing molten salts have been investigated as compared with the standard GH3535 alloy. Nb is more resistant to molten salt dissolution than Cr due to the less negative Gibbs formation energy of fluoride and the more sluggish lattice diffusion. Furthermore, it was verified the Ni-Mo-Cr-Nb alloy possesses the obvious better Te embrittlement resistance than GH3535 alloy. Our results confirmed that Ni-Mo-Cr-Nb alloy is one of the most promising candidate materials in molten salt reactors.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"603 ","pages":"Article 155450"},"PeriodicalIF":2.8,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-09DOI: 10.1016/j.jnucmat.2024.155448
Qi Sun , Yu Qin , Xiaoqiang Fan , Yanxiang Liang , Xue Mi , Minhao Zhu
Due to flow induced vibration caused by coolant circulation, fretting corrosion inevitably occurs between fuel cladding, heat exchanger tubes and their holders in Gen IV lead-bismuth eutectic (LBE) cooled nuclear reactors. In the current work, fretting corrosion behavior of 316 L steel in oxygen-saturated LBE at 500 °C has been investigated. It is shown that within the gross slip regime, the microstructure under fretting interface presents a stratified structure, composed of third body layer, oxide scales and plastic deformation layer. At the early stage of fretting corrosion, the dominant damage mechanism is fretting wear, showing that the thickness of third body layer is much larger than that of oxide scale. As fretting time increases, the dominant damage mechanism is gradually changed to LBE corrosion and fretting wear together, as the visible oxide scale is formed next to the third body layer. Moreover, the growth rate of oxide scales under fretting interface is accelerated by over an order of magnitude compared to that when 316 L steel exposed to LBE directly. In particular, after 60 h exposure, the thicknesses of oxide scale related to the worn and unworn regions are ∼4.5 μm and ∼0.2 μm, respectively. The occurrence of such phenomenon is thought to be ascribed to the severe plastic deformation under fretting contact interface, since the crystal defects served as perfectional nano-channels can promote the diffusivity of oxygen atoms. In addition, the acceleration diffusivities of oxygen atoms caused by the local high contact stress may also be responsible for this matter.
在第四代铅铋共晶（LBE）冷却核反应堆中，由于冷却剂循环引起的流动诱导振动，燃料包壳、热交换器管及其支架之间不可避免地会发生摩擦腐蚀。在当前的工作中，研究了 316 L 钢在 500 °C 氧饱和 LBE 中的摩擦腐蚀行为。研究表明，在大滑移体系中，烧蚀界面下的微观结构呈现分层结构，由第三体层、氧化鳞片和塑性变形层组成。在烧蚀的早期阶段，主要的破坏机制是烧蚀磨损，这表明第三体层的厚度远大于氧化鳞片的厚度。随着烧蚀时间的增加，主要的破坏机制逐渐转变为 LBE 腐蚀和烧蚀磨损共同作用，因为在第三体层旁边形成了可见的氧化鳞片。此外，与直接暴露于 LBE 的 316 L 钢相比，氧化物鳞片在摩擦界面下的生长速度加快了一个数量级以上。特别是在暴露 60 小时后，磨损区和未磨损区相关的氧化鳞片厚度分别为 ∼4.5 μm 和 ∼0.2 μm。这种现象的出现被认为是由于在摩擦接触界面下发生了严重的塑性变形，因为晶体缺陷作为完美的纳米通道可以促进氧原子的扩散。此外，局部高接触应力导致的氧原子加速扩散也可能是造成这种现象的原因。
{"title":"Insight into the fretting corrosion behavior of 316L steel in liquid lead-bismuth eutectic at 500°C","authors":"Qi Sun , Yu Qin , Xiaoqiang Fan , Yanxiang Liang , Xue Mi , Minhao Zhu","doi":"10.1016/j.jnucmat.2024.155448","DOIUrl":"10.1016/j.jnucmat.2024.155448","url":null,"abstract":"<div><div>Due to flow induced vibration caused by coolant circulation, fretting corrosion inevitably occurs between fuel cladding, heat exchanger tubes and their holders in Gen IV lead-bismuth eutectic (LBE) cooled nuclear reactors. In the current work, fretting corrosion behavior of 316 L steel in oxygen-saturated LBE at 500 °C has been investigated. It is shown that within the gross slip regime, the microstructure under fretting interface presents a stratified structure, composed of third body layer, oxide scales and plastic deformation layer. At the early stage of fretting corrosion, the dominant damage mechanism is fretting wear, showing that the thickness of third body layer is much larger than that of oxide scale. As fretting time increases, the dominant damage mechanism is gradually changed to LBE corrosion and fretting wear together, as the visible oxide scale is formed next to the third body layer. Moreover, the growth rate of oxide scales under fretting interface is accelerated by over an order of magnitude compared to that when 316 L steel exposed to LBE directly. In particular, after 60 h exposure, the thicknesses of oxide scale related to the worn and unworn regions are ∼4.5 μm and ∼0.2 μm, respectively. The occurrence of such phenomenon is thought to be ascribed to the severe plastic deformation under fretting contact interface, since the crystal defects served as perfectional nano-channels can promote the diffusivity of oxygen atoms. In addition, the acceleration diffusivities of oxygen atoms caused by the local high contact stress may also be responsible for this matter.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"603 ","pages":"Article 155448"},"PeriodicalIF":2.8,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-09DOI: 10.1016/j.jnucmat.2024.155444
N. Kvashin , N. Anento , G. Bonny , A. Serra , L. Malerba
Molecular Dynamics simulations, while contributing to the understanding of the mechanisms of diffusion and interactions of point defects and their clusters, are inherently limited in their temporal scope (few nanoseconds). This constraint becomes particularly evident when studying the dynamics of vacancies at low temperatures, where their jump frequency is exceedingly low, posing challenges for accurate reproduction. Additionally, the size of the simulation box imposes constraints, influencing the representation of the system and potentially affecting the accuracy of results. A relatively new kinetic activation-relaxation technique (k-ART) efficiently resolves the limitations of MD simulations, such as computation time and system dimensionality, without the need for a priori knowledge of the simulated system. This technique enables simulations lasting up to several seconds and encompassing systems with higher dimensions. In this paper we check the validity of k-ART to reproduce accurately the migration mechanisms and energies of point defects and small clusters, previously obtained by MD and validated experimentally. We point out the advantages and difficulties of using AKMC with k-ART.
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Pub Date : 2024-10-09DOI: 10.1016/j.jnucmat.2024.155449
Jiyong Huang , Yipeng Li , Yifan Ding , Jiacheng Ren , Ziqi Cao , Guang Ran
Applying an AlNbCr layer on the surface of Zr alloys significantly enhances the alloy resistance to oxidation and high-temperature corrosion. However, the effects of irradiation on AlNbCr coating remain largely unexplored. This work investigates the microstructural evolution of Cr ion-irradiated AlNbCr coatings under varying temperatures, utilizing bright-field transmission electron microscopy (TEM) observations and electron diffraction pattern analyses. With increasing Cr ion irradiation dose, the coatings gradually transitioned from an initial amorphous to a crystalline state. The onset of crystallization occurred earlier at higher temperatures, indicating that the crystallization process was significantly influenced by temperature. Moreover, the dynamic crystallization process of the crystalline structure was also analyzed, as well as the different irradiation responses at the Near-Interface Area (NIA) and Far-Interface Area (FIA). These findings provide new insights for understanding and optimizing the performance of AlNbCr coatings in high-irradiation environments.
{"title":"Recrystallization of amorphous AlNbCr coatings irradiated with chromium ions","authors":"Jiyong Huang , Yipeng Li , Yifan Ding , Jiacheng Ren , Ziqi Cao , Guang Ran","doi":"10.1016/j.jnucmat.2024.155449","DOIUrl":"10.1016/j.jnucmat.2024.155449","url":null,"abstract":"<div><div>Applying an AlNbCr layer on the surface of Zr alloys significantly enhances the alloy resistance to oxidation and high-temperature corrosion. However, the effects of irradiation on AlNbCr coating remain largely unexplored. This work investigates the microstructural evolution of Cr ion-irradiated AlNbCr coatings under varying temperatures, utilizing bright-field transmission electron microscopy (TEM) observations and electron diffraction pattern analyses. With increasing Cr ion irradiation dose, the coatings gradually transitioned from an initial amorphous to a crystalline state. The onset of crystallization occurred earlier at higher temperatures, indicating that the crystallization process was significantly influenced by temperature. Moreover, the dynamic crystallization process of the crystalline structure was also analyzed, as well as the different irradiation responses at the Near-Interface Area (NIA) and Far-Interface Area (FIA). These findings provide new insights for understanding and optimizing the performance of AlNbCr coatings in high-irradiation environments.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"603 ","pages":"Article 155449"},"PeriodicalIF":2.8,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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