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Development and verification of the higher-order mode neutron flux calculation code HARMONY2.0

Nuclear Science and Techniques 2025年第1期36卷 207-225页

作者： Er-Pin Zhang Zi-Ning Ni Nian-Biao Deng Jin-Sen Xie Yong Liu Tao Yu School of Nuclear Science and Technology University of South ChinaHengyang 421000China Key Laboratory of Advanced Nuclear Energy Design and Safety Ministry of EducationHengyang 421000China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of ChinaChengdu 610213China

Higher-order modes of the neutron diffusion/transport equation can be used to study the temporal behavior of nuclear reactors and can be applied in modal analysis, transient analysis, and online monitoring of the reactor core. Both the deterministic method and the Monte Carlo(MC) method can be used to solve the higher-order modes. However, MC method, compared to the deterministic method, faces challenges in terms of computational efficiency and α mode calculation stability, whereas the deterministic method encounters issues arising from homogenization-related geometric and energy spectra *** on the higher-order mode diffusion calculation code HARMONY, we developed a new higher-order mode calculation code, HARMONY2.0, which retains the functionality of computing λ and α higher-order modes from HARMONY1.0, but enhances the ability to treat complex geometries and arbitrary energy spectra using the MC-deterministic hybrid two-step strategy. In HARMONY2.0, the mesh homogenized multigroup constants were obtained using OpenMC in the first step,and higher-order modes were then calculated with the mesh homogenized core diffusion model using the implicitly restarted Arnoldi method(IRAM), which was also adopted in the HARMONY1.0 code. In addition, to improve the calculation efficiency, particularly in large higher-order modes, event-driven parallelization/domain decomposition methods are embedded in the HARMONY2.0 code to accelerate the inner iteration of λ∕α mode using OpenMP. Furthermore, the higher-order modes of complex geometric models, such as Hoogenboom and ATR reactors for λ mode and the MUSE-4 experiment facility for the prompt α mode, were computed using diffusion theory.

关键词： Neutron diffusion equation Higher-order modes Global homogenization Two-step method Domain

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Mechanical behavior of TiAl alloys

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Science China(Technological Sciences) 2023年第9期66卷 2457-2480页

作者： XIANG HengGao CHEN Yang QI ZhiXiang ZHENG Gong CHEN FengRui CAO YueDe LIU Xu ZHOU Bing CHEN Guang National Key Laboratory of Advanced Casting Technologies MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials TechnologyEngineering Research Center of Materials Behavior and DesignMinistry of EducationNanjing University of Science and TechnologyNanjing 210094China

Intermetallic TiAl alloys attract much attention in advanced engineering fields due to their low density(3.9–4.2 g/cm3) and excellent high-temperature properties. After more than half a century of research and development, TiAl alloys have found applications in aerospace, automotive, and related industries. However, as a kind of semi-brittle materials, intermetallic TiAl alloys exhibit different mechanical behavior from metallic and ceramic materials. Thus, it is necessary to systematically understand their mechanical behavior to ensure further developments and safe engineering applications. In this paper, the principal mechanical behavior of Ti Al alloys was reviewed comprehensively, including tension, creep, fatigue, and strengthening mechanisms. The mechanical performance and the corresponding deformation mechanisms are summarized and discussed in detail. The future directions of mechanical research on TiAl alloys are also overviewed to expedite their extensive utilization in engineering fields.

关键词： TiAl tension creep fatigue strengthening mechanisms

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Strengthening in gradient TiAl alloys

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Journal of Materials Science & technology 2023年第35期166卷 98-105页

作者： P.Li Y.Chen X.Liu X.H.Wang F.R.Chen Z.X.Qi G.Zheng H.G.Xiang G.Chen National Key Laboratory of Advanced Casting Technologies MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials TechnologyEngineering Research Center of Materials Behavior and DesignMinistry of EducationNanjing University of Science and TechnologyNanjing210094China

Gradient structure is emerging as an effective strategy to fabricate metals with remarkable mechanical performance,but have not been verified in intermetallic compounds for high-temperature *** experiments and atomic simulations,we show that a typical intermetallic TiAl alloy with gra-dient structure has a significant strengthening effect both at room temperature and high *** room-temperature compressive strength of TiAl alloys with gradient grain obtained by additive man-ufacturing is 2.57 GPa,which is∼2.7 times as strong as that with equiaxed *** strengthening effect is attributed to more sessile dislocations in gradient structure caused by the intersections of mul-tiple slip systems in gradient *** importantly,the strengthening effect is still effective at high temperatures and the compressive strength is 1.28 GPa at 750°*** simulation results show that this strengthening effect is due to the increased Hirth dislocation at high *** study expands the applications of TiAl alloys for load-bearing structures and provides a new strategy for improving the strength of intermetallic compounds at both room temperature and high temperatures.

关键词： TiAl alloys Strengthening Gradient grain Additive manufacturing Molecular dynamics

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Strengthening and toughening bulk Ni_(2)CoFeV_(0.5) medium-entropy alloy via thermo-mechanical treatment

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Journal of Materials Science & technology 2023年第20期151卷 19-29页

作者： Lei Gu Rui Hou Yi Liu Guang Chen Jihua Liu Gong Zheng Ruisheng Zhang Yonghao Zhao National Key Laboratory of Advanced Casting Technologies MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials TechnologyEngineering Research Center of Materials Behavior and DesignMinistry of EducationNanjing University of Science and TechnologyNanjing 210094China

Single-phase face-centered cubic(fcc)medium-and high-entropy alloys(MEAs/HEAs)have high ductility but low yield *** this work,the microstructures of single-phase fcc Ni_(2)CoFeV_(0.5) MEAs were tailored by cold-rolling and subsequent annealing and typical heterogeneous lamella(HL)structures composed of recrystallized micro-grain lamellae(with an averaged grain size of∼4μm)and nonrecrystallized nano-/ultrafine-grain lamellae were *** tests revealed that most HL samples exhibited excellent strength and ductility *** HL sample with∼23 vol%recrystallized grains annealed at 590℃ for 1 h had a high yield strength of 1120 MPa and a good fracture elongation of 12.3%,which increased by 5%and 46%,respectively compared with those of as-rolled ***-induced yield strength increase is attributed to high-density annealing twin boundaries(TBs)in the recrystallized grains,the annihilation of mobile dislocations inside the non-recrystallized grains,and extra heterodeformation-induced strengthening produced by the HL ***-Petch relationship of Ni_(2)CoFeV_(0.5) MEA can be reasonably described by counting both TBs and grain boundaries,with lattice friction stress of 87.3 MPa and coefficient of 722.8 MPaμm1/*** work provides optional and controllable solutions for preparing MEAs/HEAs with excellent mechanical properties by low-cost and high-efficiency thermomechanical treatments.

关键词： Medium-entropy alloys Microstructures Strength and ductility Heterogeneous lamella structure Cold-rolling Annealing

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Precipitating thermally reinforcement phase in aluminum alloys for enhanced strength at 400℃

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Journal of Materials Science & technology 2024年第5期172卷 71-82页

作者： Xiang Su Yuan Lei Yang Chen Hongjie Qu Zhixiang Qi Gong Zheng Xu Liu Henggao Xiang Guang Chen National Key Laboratory of Advanced Casting Technologies MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials TechnologyEngineering Research Center of Materials Behavior and DesignMinistry of EducationNanjing University of Science and TechnologyNanjing 210094China School of Aviation and Mechanical Engineering Changzhou Institute of TechnologyChangzhou 213032China

Heat-resistant aluminum alloys are widely used in aerospace and automotive fields for manufacturing hot components due to their advantages in lightweight design and energy ***,the high-temperature strength of existing cast aluminum alloys is always limited to about 100 MPa at 350℃due to coarsening and transformation of strengthening ***,we reveal that the yield strength and ultimate tensile strength of the T6 state Al-8.4Cu-2.3Ce-1.0Mn-0.5Ni-0.2Zr alloy at 400◦C increase by 34%and 44%after re-aging at 300℃for 100 h,and its thermal strength exhibits distinguished ad-vantage over traditional heat-resistant aluminum *** enhanced elevated-temperature strength is attributed to the reprecipitation of the Ni-bearing T-Al_(20)Cu_(2)Mn_(3)phase,whose number density increases over one *** significant segregation of Ni,Ce,and Zr elements at the interfaces helps improve the thermal stability of the T *** thermostable T phase effectively strengthens the matrix by in-hibiting dislocation ***,a highly interconnected 3D intermetallic network along the grain boundaries can still remain after long-term re-aging at 300℃,which is conducive to imposing a drag on the grain boundaries at high *** finding offers a viable route for enhancing the elevated-temperature strength of heat-resistant aluminum alloys,which could provide expanded opportunities for higher-temperature applications.

关键词： Aluminum alloys Precipitation Thermally reinforcement phase Re-aging treatment High-temperature strength

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A modified maxwell-pulse thermoplastic constitutive model of in-situ Ta-particle reinforced Zr-based bulk metallic glass composites

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Progress in Natural Science:Materials International 2024年第4期34卷 753-766页

作者： Pan Gong Zhuang Wang Guoqing Yu Maojun Li Xin Zhuo Xuefeng Tang Mao Zhang Lei Deng Junsong Jin A.A.Churakova Xinyun Wang State Key Laboratory of Materials Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle Hunan University Institute of Molecule and Crystal Physics Ufa Federal Research Center RAS

The impact of different Ta contents on the mechanical properties and thermoplastic forming ability of in-situ Taparticle reinforced Zr–Cu–Al–Ni bulk metallic glass composites was studied. The composition(Zr55Cu30Al10-Ni5)94Ta6with the best comprehensive performance was chose for a systematic investigation into its thermoplastic behavior in the supercooled liquid region（SLR）, with quantitative analysis conducted by the strain rate sensitivity index and activation volume. The steady-state flow stress and the stress overshoot intensity were augmented with deformation temperature decreasing, strain rate increasing, and the addition of the secondary phase, leading to a transition from Newtonian to non-Newtonian flow regime. The addition of the secondary phase deteriorated the rheological properties of the material. To solve the problem that the Maxwell-Pulse constitutive model showed an inability to accurately describe the steady-state flow process. A modified constitutive relationship, introducing the effect of the volume fraction of Ta particles on viscosity and elastic modulus in the steady-state flow process which was ignored in Maxwell-pulse model, was established. The fitting results of the true stress-strain curves of the modified Maxwell-pulse constitutive model were in better agreement with the experimental date than those of the Maxwell-pulse constitutive model, with higher prediction accuracy. The modified constitutive model well predicted the thermoplastic deformation behavior of(Zr55Cu30Al10Ni5)*** influence mechanism of Ta particles on the flow behavior was explained that Ta particles increased the viscosity of amorphous matrix, thereby hindering its flow and ultimately leading to an increase in flow stress.

关键词： Bulk metallic glass composites Supercooled liquid region Thermoplastic deformation Constitutive model Influence mechanism

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In-situ X-ray computed tomography tensile tests and analysis of damage mechanism and mechanical properties in laser powder b e d fused Invar 36 alloy

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Journal of Materials Science & technology 2024年第8期175卷 29-46页

作者： Qidong Yang Shuo Yang Shiyu Ma Junhan Zhou Ye Zhou Rongzheng Huang Kai Wei Zhaoliang Qu Xujing Yang Key Laboratory of Advanced Design and Simulation Techniques for Special Equipment Ministry of EducationHunan UniversityChangsha 410082China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China State Key Laboratory of Precision Manufacturing for Extreme Service Performance Central South UniversityChangsha 410083China

Laser powder bed fusion(LPBF)is a potential additive manufacturing process to manufacture Invar 36 alloy components with complicated *** it inevitably introduces specific microstructures and pore defects,which will further influence the mechanical ***,aiming at exploring the LPBF process-related microstructures and pore defects,and especially their influences on the damage mechanism and mechanical properties,Invar 36 alloy was manufactured by LPBF under designed different laser scanning *** microstructure observations reveal that higher scanning speeds lead to equiaxed and short columnar grains with higher dislocation density,while lower scanning speeds result in elongated columnar grains with lower dislocation *** pore defects analyzed by X-ray computed tomography(XCT)suggest that the high laser scanning speed gives rise to numerous lamellar and large lack-of-fusion(LOF)pores,and the excessively low laser scanning speed produces relatively small keyhole pores with high ***,the insitu XCT tensile tests were originally performed to evaluate the damage evolution and failure ***,high laser scanning speed causes brittle fracture due to the rapid growth and coalescence of initial lamellar LOF pores along the scan-ning *** laser scanning speed induces ductile fracture originating from unstable depressions in the surfaces,while metallurgical and keyhole pores have little impact on damage ***,the process-structure-property correlation is *** presence of high volume fraction of lamel-lar LOF pores,resulting from high scanning speed,leads to inferior yield strength and ***,specimens without LOF pores exhibit larger grain sizes and lower dislocation density at decreased scanning speeds,slightly reducing yield strength while slightly enhancing *** understanding lays the foundation for widespread applications of LPBF-processed Invar 36 alloy

关键词： Invar 36 alloy Laser powder bed fusion Microstructure Pore defects Mechanical property X-ray tomography in-situ tensile test

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Non-negligible role of gradient porous structure in superelasticity deterioration and improvement of NiTi shape memory alloys

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Journal of Materials Science & technology 2024年第19期186卷 48-63页

作者： Yintao Zhang Daixiu Wei Yang Chen Lechun Xie Liqiang Wang Lai-Chang Zhang Weijie Lu Guang Chen State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China National Key Laboratory of Advanced Casting Technologies MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials TechnologyEngineering Research Center of Materials Behavior and DesignMinistry of EducationNanjing University of Science and TechnologyNanjing 210094China Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of TechnologyWuhan 430070China School of Engineering Edith Cowan University270 Joondalup DriveJoondalupWA 6027Australia

Bone-mimicking gradient porous NiTi shape memory alloys(SMAs)are promising for orthopedic im-plants due to their distinctive superelastic functional ***,premature plastic deformation in weak areas such as thinner struts,nodes,and sharp corners severely deteriorates the superelasticity of gradient porous NiTi *** this work,we prepared gradient porous NiTi SMAs with a porosity of 50%by additive manufacturing(AM)and achieved a remarkable improvement of superelasticity by a simple solution treatment *** solution treatment,phase transformation temperatures dropped signif-icantly,the dislocation density decreased,and partial intergranular Ti-rich precipitates were transferred into the *** to as-built samples,the strain recovery rate of solution-treated samples was nearly doubled at a pre-strain of 6%(up to 90%),and all obtained a stable recoverable strain of more than 4%.The remarkable superelasticity improvement was attributed to lower phase transformation tem-peratures,fewer dislocations,and the synergistic strengthening effect of intragranular multi-scale Ti-Ni ***,the gradient porous structure played a non-negligible role in both superelasticity deterioration and *** microstructure evolution of the solution-treated central strut after constant 10 cycles and the origin of the stable superelastic response of gradient porous NiTi SMAs were *** work provides an accessible strategy for improving the superelastic performance of gra-dient porous NiTi SMAs and proposes a key strategy for achieving such high-performance architectured materials.

关键词： Shape memory alloys Superelasticity Gradient porous structure Solution treatment Stable recoverable strain

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Topological magnetoelectric response in ferromagnetic axion insulators

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National Science Review 2024年第2期11卷 8-14页

作者： Yuhao Wan Jiayu Li Qihang Liu Department of Physics and Shenzhen Institute for Quantum Science and Engineering(SIQSE) Southern University of Science and Technology Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices Southern University of Science and Technology Guangdong Provincial Key Laboratory for Computational Science and Material Design Southern University of Science and Technology

The topological magnetoelectric effect （TME） is a hallmark response of the topological field theory,which provides a paradigm shift in the study of emergent topological ***,its direct observation is yet to be realized due to the demanding magnetic configuration required to gap all surface ***,we theoretically propose that axion insulators with a simple ferromagnetic configuration,such as the MnBi2Te4/（Bi2Te3）nfamily,provide an ideal playground to realize the *** the designed triangular prism geometry,all the surface states are magnetically *** a vertical electric field,the surface Hall currents give rise to a nearly half-quantized orbital moment,accompanied by a gapless chiral hinge mode circulating in ***,the orbital magnetization from the two topological origins can be easily distinguished by reversing the electric *** work paves the way for direct observation of the TME in realistic axion-insulator materials.

关键词： topological magnetoelectric effect axion insulator magnetic topological materials

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Tensile Properties and Wear Resistance of Mg Alloy Containing High Si as Implant Materials

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Journal of Renewable Materials 2023年第4期11卷 1977-1989页

作者： Mengqi Cong Yang Zhang Yunlong Zhang Xiao Liu Yalin Lu Xiaoping Li Key Laboratory of Advanced Materials Design and Additive Manufacturing of Jiangsu Province Jiangsu University of TechnologyChangzhou213001China

Magnesium alloy has been considered as one of the third-generation biomaterials for the regeneration and support of functional bone *** a regeneration implant material with great potential applications,in-situ Mg_(2)Si phase reinforced Mg-6Zn cast alloy was comprehensively studied and expected to possess excellent mechanical properties via the refining and modifying of Mg_(2)Si *** present study demonstrates that the primary and eutectic Mg_(2)Si phase can be greatly modified by the yttrium(Y)*** size of the primary Mg_(2)Si phases can be reduced to~20μm with an addition of 0.5 wt.%*** phenomenon is mainly attributed to the poisoning effect of the Y ***,wear resistance and tensile properties of the ternary alloy have also been improved by the Y ***-6Zn-4Si-0.5Y alloy exhibits optimal tensile properties and wears *** ultimate tensile strength and the elongation of the alloy with 0.5 wt.%Y are 50%and 65%higher than those of the ternary alloy,*** Y addition(1.0 wt.%)deteriorates the tensile properties of Mg-Zn-Si *** improvement of the tensile properties is mainly due to the modification of primary and eutectic Mg_(2)Si phases as well as the solid solution strengthening of the Y *** study provides a certain implication for the application of Mg-Zn-Si alloys containing Y elements as regeneration implants.

关键词： Magnesium alloys Mg2Si phase microstructure regeneration mechanical properties

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