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Tian X.F.,Chengdu University of Technology | Gao T.,University of Sichuan | Xiao H.X.,National Key Laboratory For Nuclear Fuel And Materials | Lu C.H.,Chengdu University of Technology
Indian Journal of Physics | Year: 2014

Collision cascades near symmetrical tilt grain boundaries in UO2 have been investigated at energy of 5 keV. Primary knock-on atom with a distance of 3.5 nm from grain boundaries has been accelerated towards and perpendicular to the interface. Evolvement of the cascade is tracked employing classical molecular dynamics. Time evolution of the number of displaced atoms, Frenkel pairs and replacement atoms created by cascade is given. Simulations suggest that misorientation angle of the grain boundary has no effect on the final number of displaced atoms and replacement atoms. Additionally, final spatial distribution of displaced atoms at the end of the simulations has been investigated. © 2013 IACS. Source

Liu Y.,Southwest Petroleum University | Huang H.,National Key Laboratory For Nuclear Fuel And Materials | Pan Y.,State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals | Zhao G.,Southwest Petroleum University | Liang Z.,Southwest Petroleum University
Journal of Alloys and Compounds | Year: 2014

The phase transition, formation enthalpies, elastic properties and electronic structure of Pt3Al alloys are studied using first-principle approach. The calculated results show that the pressure leads to phase transition from tetragonal structure to cubic structure at 60 GPa. With increasing pressure, the elastic constants, bulk modulus and shear modulus of these Pt3Al alloys increase linearly and the bond lengths of Pt-Al metallic bonds and the peak at EF decrease. The cubic Pt 3Al alloy has excellent resistance to volume deformation under high pressure. We suggest that the phase transition is derived from the hybridization between Pt and Al atoms for cubic structure is stronger than that of tetragonal structure and forms the strong Pt-Al metallic bonds under high pressure. © 2014 Elsevier B.V. All rights reserved. Source

Zhang L.,Shanghai JiaoTong University | Bao Y.,Shanghai Nuclear Engineering Research and Design Institute | Tang R.,National Key Laboratory For Nuclear Fuel And Materials
Nuclear Engineering and Design | Year: 2012

Supercritical water cooled reactor (SCWR) is a promising Gen IV high performance reactor which can be developed for future large capacity electric power plants. However, the material selection for fuel cladding still remains one of the key issues. For a typical prototype SCWR design with outlet coolant temperature of 510°C and pressure of 25 MPa, the hot spot temperature on fuel cladding exceeds 600°C at normal operation conditions, and will be much higher during transients. Materials for fuel cladding should have good mechanical properties to meet the harsh working conditions in order to keep the integrity of fuel rod under normal and abnormal operational conditions, while corrosion in supercritical water and neutron irradiation damage will not lead to significant loss of strength and ductility, or lead to unacceptable deformation during service life. Materials for ultra-supercritical fossil fire plants, fast breeder reactor and jet air engines etc., are proposed as the candidate materials for SCWR fuel cladding. This paper reports the results based on corrosion screening tests of candidate materials exposed in supercritical water up to 650°C. Results show that their corrosion rates increase significantly with the increase of temperature, and the protective oxide films of most candidate materials turn to be unstable above temperature of 600°C. According to the present knowledge available, austenitic stainless steels with high Cr concentration show better performance and are more potential to be the references for developing the SCWR fuel cladding material. © 2012 Elsevier B.V. Source

Pan Y.,Southwest Petroleum University | Lin Y.,Southwest Petroleum University | Wang H.,National Key Laboratory For Nuclear Fuel And Materials | Zhang C.,Southwest Petroleum University
Materials and Design | Year: 2015

The effect of vacancy on mechanical properties of α-Nb5Si3 is systematically investigated by first-principles calculations. Four different mono vacancies in this alloy are considered in detail. The vacancy formation energy, formation enthalpy, elastic modulus, hardness, B/G ratio, thermodynamic properties and electronic structure of α-Nb5Si3 with different vacancies are discussed. The calculated vacancy formation energies show that Nb vacancies are more stable than that of Si vacancies, and α-Nb5Si3 prefers to form the Nb-va2 vacancy. Those vacancies weaken the volume, shear deformation resistances and reduce the elastic stiffness. However, those vacancies result in brittle-to-ductile transition and α-Nb5Si3 with Si-va1 mono vacancy exhibits ductile behavior. The calculations of electronic structure reveal that these vacancies change the localized hybridization between Nb-Si and Nb-Nb atoms, which are the origin of brittle-to-ductile transition. Finally, we conclude that vacancy is beneficial for improving the ductility of Nb5Si3. © 2015 Elsevier Ltd. Source

Tian X.,University of Sichuan | Gao T.,University of Sichuan | Jiang G.,University of Sichuan | He D.,University of Sichuan | Xiao H.,National Key Laboratory For Nuclear Fuel And Materials
Computational Materials Science | Year: 2012

Ab initio calculations based on density functional theory have been carried to investigate the incorporation and solution of krypton in uranium dioxide. The GGA and GGA + U approximations were used with the projector-augmented-wave method. Several defects that are likely to accommodate the incorporation of krypton in UO 2, such as oxygen and uranium vacancy, divacancy and Schottky defects were considered in this work. Both our SP-GGA and SP-GGA + U calculations suggested that the lowest incorporation energy corresponds to the divacancy. With SP-GGA method, the solution energies are positive whatever the trapping site considered, which confirms that Kr atoms are insoluble in UO 2, but notable discrepancy exits between the results calculated by SP-GGA + U and SP-GGA. We highlight that the use of SP + GGA + U significantly increases the number of the energy minima of the system. Furthermore, the concentrations of the point defects and the solution energy of Kr for the different incorporation sites as a function of the stoichiometry were also obtained when the deviation from stoichiometry is small. © 2011 Elsevier B.V. All rights reserved. Source

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