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Liu J.,Nanjing University of Aeronautics and Astronautics | Tang X.,Nanjing University of Aeronautics and Astronautics | Tang X.,Jiangsu Key Laboratory of Nuclear Energy Equipment Materials Engineering | Chen F.,Nanjing University of Aeronautics and Astronautics | And 3 more authors.
Science China Technological Sciences | Year: 2015

Maintaining the safety and reliability of nuclear engineering materials under a neutron irradiation environment is significant. Atomic-scale simulations are conducted to investigate the mechanism of irradiation-induced vacancy formation in CLAM, F82H and α-Fe with different neutron energies and objective laws of the effect of vacancy concentration on mechanical properties of α-Fe. Damage of these typical metal engineering materials caused by neutrons is mainly displacement damage, while the displacement damage rate and the non-ionizing effect of neutrons decrease with the increase of neutron energy. The elastic modulus, yield strength, and ultimate strength of α-Fe are in the order of magnitude of GPa. However, the elastic modulus is not constant but decreases with the increase of strain at the elastic deformation stage. The ultimate strength reaches its maximum value when vacancy concentration in α-Fe is 0.2%. On this basis, decreasing or increasing the number of vacancies reduces the ultimate strength. © 2015 Science China Press and Springer-Verlag Berlin Heidelberg Source


Liu J.,Nanjing University of Aeronautics and Astronautics | Tang X.,Nanjing University of Aeronautics and Astronautics | Tang X.,Jiangsu Key Laboratory of Nuclear Energy Equipment Materials Engineering | Chen F.,Nanjing University of Aeronautics and Astronautics | And 4 more authors.
Diamond and Related Materials | Year: 2016

It is of great significance to provide theoretical guidance to the application of carbon nanotubes as adhesive materials via the investigation on their adhesion force. In this paper, molecular dynamics was adopted to investigate the adhesion force between the graphene substrate and the carbon nanotubes with varying deformation degrees and diverse types of irradiation induced defects at different temperatures. No obvious adhesion force was found between the carbon nanotube and graphene until the deformation degree of the former reached > 70%. The adhesion force would be maintained at a high level when the temperature was in the range of 280–320 K, which limited its application. Moreover, the adhesion force between carbon nanotube with vacancies and graphene substrate would decrease with increasing size of vacancies. Finally, compared with monovacancies and divacancies, Stone-Wales defects most remarkably reduced the adhesion force of carbon nanotubes. © 2016 Elsevier B.V. Source


Chen F.,Nanjing University of Aeronautics and Astronautics | Tang X.,Nanjing University of Aeronautics and Astronautics | Tang X.,Jiangsu Key Laboratory of Nuclear Energy Equipment Materials Engineering | Huang H.,Nanjing University of Aeronautics and Astronautics | And 5 more authors.
Applied Surface Science | Year: 2015

3 MeV Xe20+ ion irradiation experiments were performed on the Cr/W multilayer films to investigate the evolution of surface morphology and mechanical properties. Results showed that the W layer in the as-deposited pure W and Cr/W multilayer films are simple cubic structure, but it is not stable under ions irradiation. After exposure to 2.14 × 1018 m-2 Xe ions irradiation, the W layer has completely transformed into the bcc structure. For surface morphology characterization, serious swelling effects were observed in the pure W films. Compared with the pure W films, the Cr/W multilayer films showed much better resistance against the irradiation-induced swelling. Meanwhile, the decrease of hardness and Young's modulus of the Cr/W multilayer films was also less than the pure W films. Results of surface morphology and mechanical tests suggested that radiation tolerance of the Cr/W multilayer films is significantly better than the pure W films. © 2015 Elsevier B.V. All rights reserved. Source


Chen F.,Nanjing University of Aeronautics and Astronautics | Tang X.,Nanjing University of Aeronautics and Astronautics | Tang X.,Jiangsu Key Laboratory of Nuclear Energy Equipment Materials Engineering | Yang Y.,Nanjing University of Aeronautics and Astronautics | And 4 more authors.
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2015

Abstract Metallic multilayer nanocomposites are known to have excellent interface self-healing performance when it comes to repairing irradiation damages, thus showing promise as structural materials for advanced nuclear power systems. The present study investigated the neutron irradiation displacement damage rate, spectra of the primary knocked-on atoms (PKAs) produced in the cascade collision, and the H/He ratio in four kinds of metallic multilayer nanocomposites (Cu/Nb, Ag/V, Fe/W, and Ti/Ta) versus neutrons' energy. Results suggest that the three neutron induced damage effects in all multilayer systems increased with the increasing of incident neutrons' energy. For fission reactor environment (1 MeV), multilayer's displacement damage rate is 5-10 × 1022 dpa/(n/cm2) and the mean PKAs energy is about 16 keV, without any noteworthy H/He produced. Fe/W multilayer seems very suitable among these four systems. For fusion reactor environment (14 MeV), the dominant damage effect varies in different multilayer systems. Fe/W multilayer has the lowest displacement damage under the same neutron flux but its gaseous transmutation production is the highest. Considering the displacement damage and transmutation, the irradiation resistance of Ag/V and Ti/Ta systems seems much greater than those of the other two. © 2015 Elsevier B.V. Source


Wang P.,Nanjing University of Aeronautics and Astronautics | Tang X.,Nanjing University of Aeronautics and Astronautics | Tang X.,Jiangsu Key Laboratory of Nuclear Energy Equipment Materials Engineering | Chai H.,Nanjing University of Aeronautics and Astronautics | And 3 more authors.
Fusion Engineering and Design | Year: 2015

The design and fabrication of shielding materials with good heat-resistance and mechanical properties is a major problem in the radiation shielding field. In this paper, based on gamma ray and neutron shielding theory, a continuous carbon-fiber reinforced Sm2O3/polyimide gamma ray/neutron shielding material was fabricated by hot-pressing method. The material's application behavior was subsequently evaluated using neutron shielding, photon shielding, mechanical tensile, and thermogravimetric analysis-differential scanning calorimetry tests. The results show that the tensile strength of the novel shielding material exceeds 200MPa, which makes it of similar strength to aluminum alloy. The material does not undergo crosslinking and decomposition reactions at 300°C and it can be used in such environments for long periods of time. The continuous carbon-fiber reinforced Sm2O3/polyimide material has a good shielding performance with respect to gamma rays and neutrons. The material thus has good prospects for use in fusion reactor system and nuclear waste disposal applications. © 2015 Elsevier B.V. Source

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