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spallation Process of Thermally Grown Oxides by In-Situ CCD Monitoring Technique

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Journal of Iron and Steel Research(International) 2009年第6期16卷 90-94页

作者： QI Yu-hong Philippe Lours Yannick Le Maoult Materials Science and Engineering Department Dalian Maritime University Dalian 116026 Liaoning China Research Centre on Tools Materials and Processes Ecole des Mines 81013 Albi France

In cooling process of Fe-Cr-Al alloy oxidized at 1 300 ℃, the effect of cooling speed and exposure time on oxide spalled area fraction and successive variety of the spalled region were studied by investigating evolvement of the thermally grown oxide using in-situ CCD monitoring technique. The results showed that oxide spallation can be restrained by controlling cooling speed and the critical temperature drop of spallation initiation which is closely related to the oxide thickness or exposure time, and the spallation process of a little region may be described in more detail as two routes： from the oxide/substrate interface micro-decohesion, micro-buckles, buckle spreading, buckle crack to spallation and from the interface micro-decohesion, micro-buckles, buckle crack and spallation to the residual oxide decohesion and spallation.

关键词： in-situ CCD monitoring technique spallation thermally grown oxide Fe-Cr-AI

Yield of long-lived fission product transmutation using proton-, deuteron-, and alpha particle-induced spallation

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Nuclear Science and Techniques 2021年第9期32卷 73-83页

作者： Meng-Ting Jin Su-Yang Xu Guan-Ming Yang Jun Su Sino-French Institute for Nuclear Energy and Technology Sun Yat-sen UniversityZhuhai 519082China

The transmutation of long-lived fission products through spallation induced by light nuclides was investi-gated for the purpose of determining the feasibility of this approach for long-lived fission products,in both economic and environmental terms.The cross-section data were obtained from the TALYS Evaluated Nuclear Data Library(TENDL).A thick target model was used to study the consumption of the target isotopes in the transmutation process.The transmutation yield was calculated using the highest beam intensity available with the China initiative accelerator-driven system.It was found that the light nuclide-induced spallation reaction can significantly reduce the radio toxicity of the investigated long-lived fission products.Using the transmutation target made of elemental LLFP and the proton beam with an intensity of 5 mA,the consumption of 90 Sr,93 Zr,107 Pd,or 137 Cs can reach approximately 500 g per year.

关键词： Transmutation Long-lived fission products spallation

Atomic-level mechanism of spallation microvoid nucleation in medium entropy alloys under shock loading

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Science China(Technological Sciences) 2021年第7期64卷 1360-1370页

作者： XIE ZhouCan CHEN Yan WANG HaiYing DAI LanHong State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing100190China School of Engineering Science University of Chinese Academy of SciencesBeijing101408China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China

spallation, rupture under impulsive tensile loading, is a dynamic failure process involving the collective evolution and accumulation of enormous microdamage in solids. In contrast to traditional alloys, the spallation mechanism in medium entropy alloys, the recently emerged multiprinciple and chemically disordered alloys, is poorly understood. Here we conduct molecular dynamics simulations and first principle calculations to investigate the effects of impact velocities and the local chemical order on spallation microvoid nucleation in a CrCoNi medium entropy alloy under shock wave loading. As the impact velocity increases, the microvoid nucleation site exhibits a transition from the grain boundaries to the grains to release redundant imposed energy. During the intragranular nucleation process, microvoids nucleate in the poor-Cr region with a large local nonaffine deformation, which is attributed to the weak metallic bonds in this position with sparse free electrons. For intergranular nucleation, a Franke-like dislocation source forms through the dislocation reaction, leading to enormous dislocations piling up in a narrow twin stripe, which markedly increases the local stored energy and promotes microvoid nucleation. These results shed light on the mechanism of spallation in chemically complexed medium entropy alloys.

关键词： high/medium entropy alloys spallation microvoid nucleation chemical order

A dynamical description of the ^(136)Xe+p spallation at 1000 MeV/nucleon

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Chinese Physics C 2019年第2期43卷 99-106页

作者：张凡苏军 Department of Electronic Information and Physics Changzhi University Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen University

We propose a dynamical description of the ^(136)Xe + p spallation at 1000 MeV/nucleon with the aim of probing the mechanism which rules the production of intermediate-mass fragments(IMF). The isospin-dependent quantum molecular dynamics(IQMD) model is used to describe the dynamical process of spallation until hot fragments with excitation energy less than a certain value E_(stop) are formed. The statistical code GEMINI is applied to simulate the light-particle evaporation from hot fragments. It is found that IMF production is well described by the model when E_(stop)= 2 MeV/nucleon is used. Comparison of the calculated mean neutron-to-proton ratio and the experimental data indicates that E_(stop) should be 3 MeV/nucleon.

关键词： spallation intermediate-mass fragment quantum molecular dynamics

Assessment of the power deposition on the MEGAPIE spallation target using the GEANT4 toolkit

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Nuclear Science and Techniques 2019年第4期30卷 8-14页

作者： Abdesslam Lamrabet Abdelmajid Maghnouj Jaouad Tajmouati Mohamed Bencheikh Faculty of Sciences Dhar El Mahraz Laboratory of Integration of Systems and Advanced TechnologiesUniversity Sidi Mohamed Ben Abdellah El Hajeb

This work aims at evaluating the reliability of the GEANT4(GEometry ANd Tracking 4) Monte Carlo(MC) toolkit in calculating the power deposition on the Megawatt Pilot Experiment(MEGAPIE), the first liquid–metal spallation target worldwide. A new choice of codes to study and optimize this target is provided. The evaluation of the GEANT4 toolkit is carried out in comparison with the MCNPX and FLUKA MC codes. The MEGAPIE is an international project led by the Paul Scherrer Institute in Switzerland. It aims to demonstrate the safe operation of an intense neutron source to power the next generation of nuclear reactors, accelerator-driven systems(ADSs). In this study, we used the GEANT4 MC toolkit to calculate the power deposited by fast protons on the MEGAPIE target.The calculation focuses on several structures and regions.The predictions of our calculations were compared and discussed with that of the MCNPX and FLUKA codes,adopted by the MEGAPIE project. The comparison shows that there is a very good agreement between our results and those of the reference codes.

关键词： GEANT4 Simulation MEGAPIE target spallation Power deposition

Production threshold impact on a GEANT4 calculation of the power deposition in a fast domain: MEGAPIE spallation target

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Nuclear Science and Techniques 2019年第5期30卷 40-47页

作者： Abdesslam Lamrabet Abdelmajid Maghnouj Jaouad Tajmouati Mohamed Bencheikh Laboratory of Integration of Systems and Advanced Technologies Faculty of Sciences Dhar El mahrazUniversity Sidi Mohamed Ben Abdellah El Hajeb

The calculation time in the Monte Carlo simulations consistently represents an essential issue. It is often very long, and its decrease constitutes a challenge for the simulator. Generally, an MC simulation is qualified as quality or not according to two main criteria: the calculation time and the accuracy of the results. However, in most cases, the optimization of one criterion affects negatively the other. Therefore, a compromise between both of them is always required in this kind of simulation. The present work aims at studying the impact of the production threshold(or cut) of the GEANT4 toolkit on the calculation of the power deposition in the MEGAPIE spallation target.The production threshold of secondaries is a GEANT4 intrinsic parameter. It indicates the limit of energy we can reach in the production of secondary particles. This study has allowed us to make the following conclusions. First,the influence of the cut on the calculation of the deposited power depends on the volume size, its arrangement and the importance of the electromagnetic processes occurring within. Second, the accuracy of the calculations can be acceptable only below a given value of the cut energy.Third, this accuracy remains almost unchangeable from a certain value of the cut. The study has also made it possible to explore the prevalence of certain interactions in the zone of spallation in the MEGAPIE target.

关键词： Production threshold Power deposition spallation MEGAPIE GEANT4

Quantitative measurement of the film interface strength by laser spallation technique

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Science China Technological Sciences 2001年第6期44卷 595-604页

作者：周明张永康蔡兰 Coll. of Mat. Sci. and Engineering Jiangsu University Zhenjiang 212013 China College of Mechanical Engineering Jiangsu University Zhengjiang 212013 China

A novel laser spallation technique for quantitatively measuring the film interface strength is presented. Through the analysis of the physical procedure of the film spallation, a mathematical model is established based on the multiple reflections and transmissions of the stress waves within film, and a formula for calculating the interface strength and the strain rate is obtained. Using this method the interface strength of Cr stainless steel/TiN, AI/EPOXY and Fe/EPOXY are measured. A new method of wave-shape analysis is developed to judge the film spallation intuitionally, and to determine the spall moment, spall depth and spall strength directly. The film interface strength has been measured using single laser shock.

关键词： pulsed laser film interface strength spallation stress wave measurement.

A comprehensive study on the oxidation behavior and failure mechanism of(γ’+β)two-phase Ni-34Al-0.1Dy coating treated by laser shock processing

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Journal of Materials Science & Technology 2023年第31期162卷 131-144页

作者： Bangyang Zhou Qijie Zhou Jian He Wei Wang Hongbo Guo School of Materials Science and Engineering Beihang University(BUAA)Beijing 100191China Research Institute for Frontier Science Beihang University(BUAA)Beijing 100191China Key Laboratory of High-Temperature Structural Materials&Coatings Technology(Ministry of Industry and Information Technology) Beihang University(BUAA)Beijing 100191China State Key Laboratory of Long-Life High Temperature Materials Deyang 618000China Dongfang Electric Corporation Dongfang Turbine Co. LTDDeyang 618000China

Laser shock processing(LSP),as a novel surface modification technology,exhibits tremendous potential to improve the oxidation resistance of alloys.In this paper,(γ’+β)two-phase Ni-34Al-0.1Dy coatings were prepared by electron beam physical vapor deposition(EB-PVD)and then treated by LSP with different pulse energy(4 and 5 J).Their oxidation behavior(including isothermal oxidation and cyclic oxidation)at 1150°C was compared.In the isothermal oxidation case,the LSP-treated samples exhibited good ox-idation resistance due to high dislocation density and refined grains caused by the LSP.For the cyclic oxidation,however,the LSP-treated samples were subjected to undesirable thermally grown oxide(TGO)spallation.In the early oxidation stage(within 30 min),the residual compressive stress introduced by the LSP rapidly released,resulting in a severe plastic deformation at the coating/TGO interface.As a result,the mismatch between coating and TGO gave rise to the TGO spallation.With the increase in the oxida-tion time,work hardening,which continuously limited the synchronous deformation of the TGO/coating interface,became the dominant mechanism controlling the TGO spallation of 5 J-treated coatings.The continuous TGO spallation affected the Al supply and thus deteriorated the cyclic oxidation behavior.

关键词： Ni-34Al-0.1dy coating Laser shock processing Mechanical properties Oxidation spallation

A new spallation mechanism of thermal barrier coatings on aero-engine turbine blades

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Theoretical & Applied Mechanics Letters 2018年第1期8卷 7-11页

作者： Bo Yuan Christopher M.Harvey Rachel C.Thomson Gary W.Critchlow Simon Wang Department of Aeronautical and Automotive Engineering Loughborough University Department of Materials Engineering Loughborough University School of Mechanical and Equipment Engineering Hebei University of Engineering

Laboratory experiments were conducted to study the spallation behaviour of thermal barrier coatings(TBCs) on aero-engine turbine blades manufactured by the electron-beam physical vapour deposition technique(EB-PVD). Intact blades were heated at temperature 1135℃ in a furnace for certain time and then cooled to the room temperature in the laboratory condition. It was found that no spallation occurred during cooling, but spallation happened at constant room temperature after cooling. The spallation mechanism is studied by using the mechanical model developed(Harvey 2017 and Wang 2017), which are based on the hypothesis of pockets of energy concentration(PECs). Some observations of the spallation behaviour are well predicted by the model.

关键词： Thermal barrier coating Interface fracture spallation Pockets of energy concentration Buckling