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mechanical properties,thermal conductivity and defect formation energies of samarium immobilization in Gd_(2)Zr_(2)O_(7):First-principles study and irradiation experiment

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Journal of Rare Earths 2023年第3期41卷 422-433,I0004页

作者： Yuhao Wang Jiahu Ouyang Tao Wei Gui Cao Zhanguo Liu Zhaoying Ding Yujin Wang Yaming Wang Key Laboratory of Advanced Structural-Functional Integration Materials&Green Manufacturing Technology School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China Nuclear Fuel Cycle Research Theme Australian Nuclear Science and Technology OrganisationLocked Bag 2001Kirrawee DCNSW2232Australia

A density functional theory(DFT)study was employed to investigate the mechanical property,thermal conductivity,Debye temperature,electronic structure and defect chemistry of(Gd_(1-x)Sm_(x))_(2)Zr_(2)O_(7).All the(Gd_(1-x)Sm_(x))_(2)Zr_(2)O_(7) compounds exhibit an excellent structural and mechanical stability(Gd_(0.25)Sm_(0.75))_(2)Zr_(2)O_(7) has the lowest Young’s modulus of 213.7 GPa,the largest Possion’s ratio of 0.292,the lowest Debye temperature of 491.8 K and the lowest thermal conductivity.The calculated thermal conductivities of(Gd_(1-x)Sm_(x))_(2)Zr_(2)O_(7) are 1.17-1.21 W/(m·K)by the Clark’s model and 1.32-1.36 W/(m·K)by the Cahall’s model,respectively.The formation energies of O vacancies at 48f site are negative,which increase with the Sm content,however,the formation energies of O vacancies at 8b site are almost invariable.In addition,Sm partly occupying the Gd-site reduces distinctly the formation energies of defects such as A-site vacancies,cation antisite defects,anion Frenkel pairs of oxygen at 8b site and cation interstitials,which suggests that Sm-doped Gd_(2)Zr_(2)O_(7),especially equimolar GdSmZr_(2)O_(7),has a better irradiation tolerance.After the 16 MeVTa-ion irradiation at a fluence of 1×10^(14) or 2×10^(14) ions/cm^(2),the crystal structure of GdSmZr_(2)O_(7) transforms from pyrochlore to a defect fluorite without obvious amorphous phase.

关键词： Pyrochlores First-principles calculations mechanical properties Defect formation energies Ion irradiation Rare earths

mechanical properties of thermoelectric generators

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Journal of Materials Science & Technology 2023年第17期148卷 64-74页

作者： Xin Bao Shuaihang Hou Zhixin Wu Xiaodong Wang Li Yin Yijie Liu Huolun He Sichen Duan Baolin Wang Jun Mao Feng Cao Qian Zhang School of Materials Science and Engineering and Institute of Materials Genome&Big DataHarbin Institute of TechnologyShenzhen518055China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin150001China School of Science Harbin Institute of TechnologyShenzhen518055China

To satisfy the requirements of practical applications,thermoelectric generators should be highly efficient and mechanically robust.Recently,progress in designing high-performance thermoelectric generators has been made.However,the mechanical properties of thermoelectric generators are still unsatisfactory.In this review,studies on the mechanical properties of thermoelectric generators are summarized.The me-chanical properties of bulk thermoelectric generators will be first discussed.In this section,the mechan-ical properties of thermoelectric materials and the strategies for improving their mechanical properties are emphasized.Since the device’s failure usually occurs at the interface between the thermoelectric ma-terials and electrode,the joint strength of electrodes and thermoelectric materials will be overviewed.After that,the mechanical properties of the inorganic thin-film thermoelectric devices will be discussed.Since the figure of merit for the flexibility of thermoelectric materials depends on the film thickness,elastic modulus,and yield strength,the synthesis methods of thin-film thermoelectric materials will be reviewed.Finally,this review will be concluded with a discussion on flexible organic thermoelectric de-vices and flexible devices using bulk legs.

关键词： Thermoelectric generator mechanical properties Interface Joint strength

mechanical properties and microstructural evolution of rheocast A356 semi-solid slurry prepared by annular electromagnetic stirring

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China Foundry 2023年第4期20卷 315-328页

作者： Mohammad Taghi Asadi Khanouki Department of Materials and Metallurgy Engineering Shahid Bahonar University of KermanP.O.Box ***KermanIran Mineral Industries Research Center(MIRC) Shahid Bahonar University of KermanP.O.Box ***KermanIran

Nowadays,having an effective technique in preparing semi-solid slurries for rheocasting process seems to be an essential requirement.In this study,semi-solid slurry of A356 aluminum alloy was prepared by three-phase annular electromagnetic stirring(A-EMS)technique under different conditions.The effects of stirring current,pouring temperature and stirring time on microstructural evolution,mean particle size,shape factor and solid fraction were investigated.The rheocasting process was carried out by using a drop weight setup and to inject the prepared semi-solid slurry in optimal conditions into the step-die cavity.The filling behavior and mechanical properties of parts were studied.Microstructural evolution showed that the best semi-solid slurry which had fine spherical particles with the average size of~27μm and a shape factor of~0.8 was achieved at the stirring current of 70 A,melt pouring temperature of 670℃,and stirring time of 30 s.Under these conditions,the step-die cavity was completely filled at die preheating temperature of 470℃.The hardness increases by decreasing step thickness as well as die preheating temperature.Moreover,the tensile properties are improved at lower die preheating temperatures.The fracture surface,which consists of a complex topography,indicates a typical ductile fracture.

关键词： semi-solid slurry annular electromagnetic stirring rheocast A356 aluminum alloy microstructural evolution mechanical properties magnetic flux density

mechanical properties and damage constitutive model of sandstone after acid corrosion and high temperature treatments

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International Journal of Mining Science and Technology 2023年第6期33卷 747-760页

作者： Qijian Chen Youliang Chen Peng Xiao Xi Du Yungui Pan Rafig Azzam Department of Civil Engineering School of Environment and ArchitectureUniversity of Shanghai for Science and TechnologyShanghai 200093China Department of Engineering Geology and Hydrogeology RWTH Aachen UniversityAachen 52064Germany School of Civil and Environmental Engineering University of New South WalesSydney 2052Australia

Aiming at the problem of temperature-mechanics-chemical(T-M-C)action encountered by rocks in underground engineering,sandstone was selected as the sample for acid corrosion treatment at pH 1,3,5 and 7,the acid corrosion treated samples were then subjected to high-temperature experiments at 25,300,600,and 900℃,and triaxial compression experiments were conducted in the laboratory.The experimental results show that the superposition of chemical damage and thermal damage has a significant impact on the quality,wave velocity,porosity and compression failure characteristics of the rock.Based on the Lemaitre strain equivalent hypothesis theory,the damage degree of rock material was described by introducing damage variables,and the spatial mobilized plane(SMP)criterion was adopted.The damage constitutive model can well reflect the stress-strain characteristics of the rock triaxial compression process,which verified the rationality and reliability of the model parameters.The experiment and constitutive model analyzed the change law of mechanical properties of rock after chemical corrosion and high temperature thermal damage,which had certain practical significance for rock engineering construction.

关键词： Acid corrosion High temperature mechanical properties Damage variable SMP criterion Constitutive model

mechanical properties,corrosion behavior and microstructure evolution of zinc and scandium co-strengthened 5xxx alloy

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Journal of Rare Earths 2023年第11期41卷 1819-1826,I0006页

作者： Yanlin Pan Yue Xu Di Zhang Jishan Zhang Guxin Zhou Yujing Lang China Academy of Ordnance Science Ningbo Branch Ningbo315103China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing100083China

Nowadays,it is a challenge to improve the strength of 5xxx aluminium alloy while maintaining its distinctive properties.To address this,the Zn and Sc modified high strength 5xxx aluminium alloys with good intergranular corrosion resistance were prepared through chill casting,and the effects of minor Sc on mechanical properties,corrosion behavior and microstructure evolution of Al-5.0Mg-3.0Zn alloys were systematically investigated.The results show that the Sc containing alloy has high number density and small size of intragranular precipitates,combined with the solid solution strengthening of Sc and the Al_(3)(Sc_(1-x),Zr_(x))second phase strengthening,the strength of Al-5.0Mg-3.0Zn-0.1Sc alloy is obviously enhanced.Meanwhile,the intergranular corrosion resistance of the Sc containing alloy is also improved due to the formation of a large number of low angle grain boundaries and the weakening of the continuity of precipitated phases along the grain boundaries.

关键词： Al-Mg-Zn Scandium mechanical properties Intergranular corrosion Transmission electron microscopy(TEM) Rare earths

mechanical properties of Al-15Mg_(2)Si composites prepared under different solidification cooling rates

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International Journal of Minerals,Metallurgy and Materials 2022年第6期29卷 1249-1260页

作者： E.Safary R.Taghiabadi M.H.Ghoncheh Department of Materials Science and Metallurgy Imam Khomeini International UniversityQazvinIran Department of mechanical Engineering University of New BrunswickFrederictonNBCanada

The effect of different cooling rates(2.7,5.5,17.1,and 57.5℃/s)on the solidification parameters,microstructure,and mechanical properties of Al-15Mg_(2)Si composites was studied.The results showed that a high cooling rate refined the Mg_(2)Si particles and changed their morphology to more compacted forms with less microcracking tendency.The average radius and fraction of primary Mg_(2)Si particles decreased from 20μm and 13.5%to about 10μm and 7.3%,respectively,as the cooling rate increased from 2.7 to 57.5℃/s.Increasing the cooling rate also improved the distribution of microconstituents and decreased the grain size and volume fraction of micropores.The mechanical properties results revealed that augmenting the cooling rate from 2.7 to about 57.5℃/s increased the hardness and quality index by 25%and245%,respectively.The high cooling rate also changed the fracture mechanism from a brittle-dominated mode to a high-energy ductile mode comprising extensive dimpled zones.

关键词： Al-15Mg_(2)Si composite solidification cooling rate thermal analysis mechanical properties

mechanical properties of thermal aged HTPB composite solid propellant under confining pressure

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Defence Technology（防务技术） 2022年第4期18卷 618-625页

作者： Zhe-jun Wang Hong-fu Qiang 206 Staff Room Xi’an Hi-Tech InstituteXi'an710025PR China

With the purpose of investigating the effects of confining pressure and aging on the mechanical properties of Hydroxyl-terminated polybutadiene(HTPB)based composite solid propellant,tensile tests of thermal accelerated aged propellant samples under room temperature and different confining pressure conditions were performed through the use of a self-made confining pressure device and conventional testing machine.Afterwards,the maximum tensile stressσmand the corresponding strainεm for the propellant under different test conditions were obtained and analyzed.The results indicate that confining pressure and aging can significantly affect the mechanical properties of HTPB propellant,and the coupled effects are very complex.On the one hand,the stressσmincreases as a whole when confining pressure becomes higher or thermal aging time rises.Besides,this stress is more sensitive to aging with increasing confining pressure.There are almost three regions in the stress increments(σm P-σm0)/σm0and thermal aging time curves for HTPB propellant.The maximum value of the stress increment(σm P-σm0)/σm0for the propellant is about 98%at 7.0 MPa and 170 d.On the other hand,the strainεm decreases with increasing thermal aging time under the whole confining pressure conditions.However,the variation of this strain with confining pressure is more complex at various thermal aging time,which is different from that of unaged solid propellant in previous researches.In addition,this strain is slightly less sensitive to aging as the confining pressure increases.Furthermore,there is also a critical confining pressure in this investigation,whose value is between 0.15 MPa and 4.0 MPa.Beyond this critical pressure,the trends of the stressσmand the corresponding strainεm all change.Moreover,there are some critical thermal aging time for the stress increment(σm P-σm0)/σm0and strain increment(εm P-εm0)/εm0of HTPB propellant in this investigation,which are about at 35,50 and 170 d.Finally,based on the twin-shear strength theory,a new modified nonlinea

关键词： Thermal accelerated aging Confining pressure Hydroxyl-terminated polybutadiene propellant mechanical properties Strength criterion

mechanical properties and microstructure characteristics of lattice-surfaced PEEK cage fabricated by high-temperature laser powder bed fusion

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Journal of Materials Science & Technology 2022年第30期125卷 105-117页

作者： Peng Chen Jin Su Haoze Wang Lei Yang Haosong Cai Maoyuan Li Zhaoqing Li Jie Liu Shifeng Wen Yan Zhou Chunze Yan Yusheng Shi State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan430074China School of Logistics Engineering Wuhan University of TechnologyWuhan430081China Faculty of Engineering China University of GeosciencesWuhan430079China

Porous structure design on the contact surface is crucial to promote the osseointegration of the intervertebral cage while preventing subsidence and displacement.However,the stress response will undergo significant changes for the current random porous cages,which can directly affect the mechanical properties and long-term usability.Here,this paper proposed a newly designed polyetheretherketone(PEEK)cage with the triply periodic minimal surface(TPMS)-structured lattice surfaces to provide tailored 3 D microporosity and studied the mechanical performance,stress/strain responses,and microstructure changes in depth.The lattice-surfaced PEEK cage mainly exhibits a multiple-point-plane stress transfer mechanism.The compression modulus and elastic limit can be adjusted by controlling the area of the Diamond TPMS surface while the energy absorption efficiency remains stable.The microstructure of high-strength PEEK is featured by the radial pattern morphology.Meanwhile,the double-stranded orthorhombic phase is more ordered,and the benzene plane subunit and lattice volume become more expanded.

关键词： Additive manufacturing Laser powder bed fusion Polyetheretherketone Intervertebral cage mechanical properties

mechanical properties and Corrosion Behavior of Multi-Microalloying Mg Alloys Prepared by Adding AlCoCrFeNi Alloy

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Acta Metallurgica Sinica(English Letters) 2022年第8期35卷 1301-1316页

作者： Xiong Zhou Qichi Le Chenglu Hu Ruizhen Guo Tong Wang Chunming Liu Dandan Li Xiaoqiang Li The Key Laboratory of Electromagnetic Processing of Materials Ministryof EducationNortheastern UniversityShenyang 110819China Key Laboratory for Anisotropy and Texture of Materials(MoE) School of Materials Scienceand EngineeringNortheastern UniversityShenyang 110819China

In this work,a series of multi-microalloying Mg alloys with a high degradation rate and high strength was prepared by adding AlCoCrFeNi HEA particles to the Mg melt followed by hot extrusion.The microstructure evolution and mechanical properties of the alloys were studied,meanwhile,the corrosion properties were evaluated by immersion weight loss and electrochemical tests.Results indicated that HEA particles in the Mg melt were decomposed and formed the Ni-rich phase,which was distributed uniformly in the Mg matrix.Compared with the pure Mg matrix,the Mg-3 HEA alloy exhibited excellent mechanical properties of the ultimate tensile strength~237 MPa and tensile yield strength~181 MPa,an increased rate of~49.1 and~96.7%,respectively,without sacrificing the elongation.And the ultimate compressive strength(UCS)and compressive yield strength increased by~31.5 and~43%to 392±3 and 103±2 MPa,respectively.Based on theoretical analysis,the high YS of the alloys was mainly attributed to fine-grain strengthening and second phase strengthening.Besides,based on the study of corrosion behavior,it was found that with the increase in HEA particle content,the degradation rate of the composites increased because of the promotion of micro-galvanic corrosion,and the Mg-3 HEA alloy showed a maximum degradation rate of~25.2 mg cmh.

关键词： AlCoCrFeNi HEA Pure Mg mechanical properties Corrosion behavior