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Limited Effect of Twin Boundaries on Radiation Damage

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Acta Metallurgica Sinica(English Letters) 2016年第1期29卷 72-78页

作者： Jin Gao Zhi-Jun Liu Fa-Rong Wan Department of Materials Physics and Chemistry School of Materials Science and EngineeringUniversity of Science and Technology Beijing

The different influences of the general grain boundary and the twin boundary on the cavity formation were investigated in copper irradiated by helium at room temperature. Large number of the cavities with sizes smaller than 5 nm formed after irradiation, which were almost homogenously distributed inside the grains. However, the distribution of the cavities varied near the general grain boundary and the twin boundary. Cavities-depleted zone was readily observed near the general grain boundaries, which was rarely observed near the twin boundaries. Meanwhile, decoration of dense cavities within the grain boundary plane was observed. The results suggested the limited influence of the twin boundaries as the point defect sinks compared with the general grain boundaries.

关键词： Transmission electron microscopy Cavities Cavities-depleted zone General grainboundary Twin boundary

Analysis of Oxides Formed on the Surface of the Alloy 690 in Hydrogenated Supercritical Water

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Acta Metallurgica Sinica(English Letters) 2016年第8期29卷 774-781页

作者： Jin Gao Fa-Rong Wan Guo-ping Cao Kumar Sridharan Todd Allen School of Materials Science and Engineering University of Science and Technology Beijing Department of Materials Science and Engineering University of Wisconsin-Madison

The oxides formed on the surface of the alloy 690 in hydrogenated supercritical water at 400℃ for 1000 h were investigated using scanning electron microscopy,transmission electron microscopy,scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy.The oxides on me surface of the alloy 690 exhibited multi-layer structure：an outer layer consisted of granular crystallites（NiO and NiFe_2O_4） and a compact inner layer（spinel and Cr_2O_3）.Chemical analysis indicated that the outer layer was enriched in nickel but depleted in chromium,whereas the inner layer was enriched in chromium and iron but depleted in nickel.The inner layer was also characterized as layered structure by Fe-rich spinel on top of continuous Cr_2O_3 layer.Besides,Cr_2O_3 nodules were readily observed at the oxides/alloy interface.

关键词： Alloy 690 Supercritical water Oxides Corrosion

聚变材料钨辐照后退火形成的位错环特性及inside-outside衬度分析

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物理学报 2023年第5期72卷 278-288页

作者：徐驰万发荣北京师范大学核科学与技术学院射线束技术教育部重点实验室北京100875 北京市科学技术研究院辐射技术研究所北京100875 北京科技大学材料科学与工程学院北京100086 国防科技工业核材料技术创新中心北京102413

对纯钨透射电镜薄膜样品在400℃进行了58 keV、1×10^(17)cm^(-2)(约0.1 dpa)的氘离子辐照,辐照后进行了900℃/1 h的退火处理.离子辐照产生了平均尺寸为(11.10±5.41)nm,体密度约为2.40×10^(22)m^(-3)的细小位错环组织,未观察到明显的... 详细信息

对纯钨透射电镜薄膜样品在400℃进行了58 keV、1×10^(17)cm^(-2)(约0.1 dpa)的氘离子辐照,辐照后进行了900℃/1 h的退火处理.离子辐照产生了平均尺寸为(11.10±5.41)nm,体密度约为2.40×10^(22)m^(-3)的细小位错环组织,未观察到明显的空洞组织.辐照后退火造成了位错环尺寸的长大和体密度的下降,分别为(18.25±16.92)nm和1.19×10^(22)m^(-3).通过透射电镜的衍射衬度分析,判断辐照后退火样品中的位错环主要为a/2类型位错环.通过“一步法”inside-outside衬度分析判断位错环为间隙型位错环.辐照后退火还造成了较大位错环之间接触融合,形成不规则形状的大型位错环.此外,退火后样品中还观察到了尺寸为1—2 nm的细小空洞组织.

关键词：钨离子辐照位错环 inside-outside衬度

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材料辐照损伤中的点缺陷团簇与一维迁移现象

工程科学学报 2020年第12期42卷 1535-1541页

作者：万发荣北京科技大学材料科学与工程学院北京100083

材料辐照损伤是核反应堆材料、尤其是核聚变堆材料所面临的重要问题.高能粒子(中子、离子、电子)辐照在材料中会产生大量的点缺陷,即自间隙原子和空位.这些点缺陷聚集在一起会形成自间隙原子团簇和空位团簇,从而对材料结构和性能的演化... 详细信息

材料辐照损伤是核反应堆材料、尤其是核聚变堆材料所面临的重要问题.高能粒子(中子、离子、电子)辐照在材料中会产生大量的点缺陷,即自间隙原子和空位.这些点缺陷聚集在一起会形成自间隙原子团簇和空位团簇,从而对材料结构和性能的演化产生重要影响.空位团簇包括有空洞、层错四面体、空位型位错环,而自间隙原子团簇则只有自间隙型位错环.本文介绍了两种点缺陷团簇的性质、及其对于以材料辐照肿胀为主要内容的材料辐照损伤性能的影响.作为空位团簇,比较详细介绍了具有本课题组特色的空位型位错环的研究,同时分析了合金元素和氢同位素对空位型位错环的影响.在铁试样中形成的这种空位型位错环尺寸可达100 nm左右,该空位型位错环具有两种柏氏矢量,b=和b=1/2,前者的数密度比后者高一个数量级.对于自间隙原子团簇,则重点介绍了与其相关的一维迁移现象及其研究动态,该一维迁移性能有可能是影响高熵合金辐照性能的重要因素.

关键词：点缺陷缺陷团簇一维迁移辐照损伤核聚变堆材料

Microstructure and Nano-hardness of Pure Copper and ODS Copper Alloy under Au Ions Irradiation at Room Temperature

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Acta Metallurgica Sinica(English Letters) 2016年第11期29卷 1047-1052页

作者： Jing Zhang Yong-Qin Chang Zhi-Meng Guo Ping-Ping Liu Yi Long Fa-Rong Wan School of Materials Science and Engineering University of Science and Technology Beijing

The microstructure and nano-hardness of the pure copper and oxide dispersion-strengthened（ODS） copper alloy subjected to 1.4 Me V Au ions irradiation at room temperature were investigated. After irradiation, dislocation-loops form in both materials, while voids can only be generated in the pure copper. Compared with the irradiated pure copper, larger average diameter and lower number density of irradiation-induced dislocation-loops were detected in the ODS copper alloy, revealing that high-density dislocation and large volume of Al2O3 particles existing in the ODS copper alloy can act as effective sinks for the irradiation-induced defects. It was also detected that irradiation hardening in the ODS copper alloy is lower than that in the pure copper. The microstructure and nano-hardness results reveal that the ODS copper alloy has a better irradiation tolerance than the pure copper. In addition, the average diameter of the Al2O3 particles in the ODS copper alloy decreases after irradiation, because the Al–O chemical bonds are decomposed and the atoms are redistributed in the matrix during the irradiation process. This work reveals that the irradiation tolerance of the copper can be effectively enhanced by adding nano-sized Al2O3 particles into the matrix.

关键词： Oxide dispersion-strengthened copper alloy Ions irradiation Microstructure evolution Nano-hardness

Formation of Vacancy-Type Dislocation Loops in Hydrogen-Ion-Implanted Fe–Cr Alloy

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Acta Metallurgica Sinica(English Letters) 2019年第5期32卷 566-572页

作者： Yu-Feng Du Li-Juan Cui Wen-Tuo Han Fa-Rong Wan Department of Materials Physics and Chemistry School of Materials Science and Engineering University of Science and Technology

Fe-10 at.%Cr alloy was implanted with hydrogen ions at room temperature, followed by annealing at high temperatures.The annealing process made the defects develop into large dislocation loops. The nature of the dislocation loops formed after annealing was studied by the evolution of loops under in situ electron irradiation in high-voltage electron microscope.It indicated that only interstitial-type loops were observed when annealed at 550 °C and below, but vacancy-type loops started to form at the temperature higher than 600 °C. According to the previous study of our group, the presence of chromium element made the formation temperature of vacancy-type loops higher than that in pure iron. The effect of alloying elements on the formation temperature of the vacancy-type loops was discussed.

关键词： Hydrogen implantation Interstitial-type loops Vacancy-type loops Fe–Cr alloy High-voltage electron microscope

Irradiation effects on nanocrystalline materials

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Frontiers of Materials Science 2013年第2期7卷 143-155页

作者： Yong-Qin CHANG Qiang GUO Jing ZHANG Lin CHEN Yi LONG Fa-Rong Wan School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

In recent years, nanocrystalline materials with grain size below 100 nm have attracted much interest due to their excellent chemical, physical, and optical properties. This review focuses on the irradiation effects of nanocrystalline materials. It has been generally believed that nanocrystalline materials have a great potential to increase irradiation resistance in the future reactor because of a large fraction of grain boundaries or interfaces that could absorb and annihilate mobile defects which produced during irradiation. Some calculation results and experiment results revealed that nanocrystalline materials can enhance irradiation resistance, while some reports showed that nanocrystalline materials exhibit worse irradiation resistance, or even amorphous at a lower irradiation dose compared with their bulk materials. During the irradiation process, the grain growth dominated by irradiation dose, thermal effect or defects was also disputed. Irradiation is also an important tool to tailor the grain size, phase structure and physical properties of the materials.

关键词： nanocrystalline material irradiation resistance grain growth

Microstructure,hardening and deuterium retention in CVD tungsten irradiated with neutrons at temperatures of defect recovery stagesⅡandⅢ

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Tungsten 2022年第3期4卷 248-260页

作者： Xiao-Ou Yi Tatsuya Kuwabara Vladimir KhAlimov Yu-Feng Du Wen-Tuo Han Ping-Ping Liu Bin-You Yan Jiu-Peng Song Kenta Yoshida Takeshi Toyama Fa-Rong Wan Somei Ohnuki Yuji Hatano Yasuyoshi Nagai School of Materials Science and Engineering University of Science and Technology BeijingBeijing100083China Graduate School of Engineering Nagoya UniversityFuro-choChikusa-kuNagoya464-8063Japan Frumkin Institute of Physical Chemistry and Electrochemistry Russian Academy of SciencesMoscow119071Russia Institute for Materials Research Tohoku UniversityNarita-cho 2145-2OaraiIbaraki311-1313Japan Xiamen Tungsten Co.Ltd. Xiamen361021China School of Materials Science and Engineering Xihua UniversityChengdu610039China Hydrogen Isotope Research Center University of ToyamaToyama930-8555Japan

Samples of ultra-high-purity tungsten prepared using chemical vapour deposition(CVD)technique were irradiated with neutrons at temperatures T_(irr)=373-483 K(stage Ⅱ of defect recovery)and T_(irr)=573-673 K(stage Ⅲ)up to 0.15 displacements per atom(dpa)in the Belgian reactor(BR2).The study of the microstructure of neutron-damaged samples using transmission electron microscopy(TEM)revealed visible defects with a predominance of dislocation loops.With an increase in the neutron irradiation temperature,the spatial distribution of the loops acquired pronounced inhomogeneity,and their average size moderately increased.Cavities and voids were not observed.Irradiation-induced hardening was found and a linear correlation was obtained between Vickers microhardness and nanohardness for undamaged and neutron-irradiated CVD-W samples.Irradiation of tungsten with neutrons led to a significant increase in the retention of deuterium,which accumulated mainly in vacancy-type traps.Furthermore,the influence of the columnar grain structure in low-dose neutron-irradiated tungsten seemed to be non-trivial upon deuterium retention.

关键词： CVD-W Neutron irradiation Microstructure Hardening Deuterium retention

Rationale,new anus positioning methods,and updated protocols:Expert recommendations on cap-assisted endoscopic sclerotherapy for hemorrhoids from China Gut Conference

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Chinese Medical Journal 2021年第22期134卷 2675-2677页

作者： fa-Ming Zhang Kai-Chun Wu Jing-Nan Li Xin wang Xing-Xiang He rong wan Shi-Yao Chen CAES-LPRA Study Group Medical Center for Digestive Diseases The Second Affiliated Hospital of Nanjing Medical UniversityNanjingJiangsu 210011China National Clinical Research Center for Digestive Diseases Xijing HospitalFourth Military Medical UniversityXi’anShaanxi 710032China Department of Gastroenterology Peking Union Medical College HospitalBeijing 100730China Department of Gastroenterology The First Affiliated Hospital of Guangdong Pharmaceutical UniversityGuangzhouGuangdong 510080China Department of Gastroenterology Shanghai General HospitalShanghai Jiao Tong University School of MedicineShanghai 201620China Department of Gastroenterology and Hepatology Zhongshan HospitalFudan UniversityShanghai 200032China. 不详

Injection sclerotherapy is most effective for internal hemorrhoids,especially for patients with bleeding.Howev-er,traditional sclerotherapy via anoscope may cause iatrogenic risk and complications due to misplaced injections.[1]The flexible endoscopic sclerotherapy for internal hemorrhoids using a short needle without cap assistant was first reported in 1991 in the United States.[2]The flexible endoscopic injection using a short needle with cap assistant was reported in 2014 in Japan.[3]Cap-assisted endoscopic sclerotherapy(CAES)primarily using a long needle was reported in 2015[4]as an emerging flexible endoscopic therapy,and has been widely used for internal hemorrhoids and some prolapse in China.A panel of experts aimed to develop expert recommendations for CAES and derived guidelines on the key issues in hemorrhoidal disease,including rationale,new positioning methods for anus,indications,contraindications,techniques,post-procedure management,and core outcome set for evaluation[Figure 1].

关键词： needle hemorrhoids Rational