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Transactions of Nonferrous Metals Society of China 2019年第6期29卷 1117-1126页

作者： Heng-cheng LIAO He-ting XU Yi-yun HU Jiangsu Key Laboratory for Advanced Metallic Materials School of Materials Science and Engineering Southeast University Nanjing 211189 China

The effect of RE addition on solidification process and high-temperature strength of Al-12%Si-4%Cu-1.6%Mn(in wt.%)heat-resistant alloy was investigated by microstructure observation and tensile test.A great number of fine needle-like RE-rich phases are observed in the alloys with RE addition. Solutionizing treatment does not change their morphologies and sizes, indicating that they have good thermal stability. The addition of RE totally alters the solidification process of eutectic CruAl2 phase, from network-like phase in the form of segregation at the final eutectic grain boundaries to discretely blocky phase growing on the hair-filamentous RE-rich needles. In the alloys with Ce addition, blocky CuAl2, particulate Al15Mn3Si2 and needle-like RE-rich needle phases grow together, but they did not occur in the alloy with only La addition. The addition of RE does not considerably improve the strength of the alloy at high temperatures. The formation of RE-rich phases also does not significantly alter the originating and propagating of micro-cracks in the alloy during tensile test.

关键词： Al-Si-Cu-Mn heat-resistant alloy rare earth solidification process high-temperature strength

Improvement of high-temperature strength of 6061 Al matrix composite reinforced by dual-phased nano-AlN and submicron-Al_(2)O_(3)particles

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Transactions of Nonferrous Metals Society of China 2022年第10期32卷 3197-3211页

作者： Ke-wei XIE Jin-feng NIE Kai-qi HU Xia MA Xiang-fa LIU Key Laboratory for Liquid-Solid Structural Evolution&Processing of Materials Ministry of EducationShandong UniversityJinan 250061China Nano and Heterogeneous Materials Center School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China School of Mechanical Engineering Shandong University of TechnologyZibo 255000China

Nano-AlN and submicron-Al_(2)O_(3) particles were simultaneously utilized in a 6061 Al matrix composite to improve the high-temperature *** to the SEM and TEM characterization,nano-AlN and submicron-Al_(2)O_(3) particles are uniformly distributed in the Al *** hardness results indicate that different from the traditional 6061 Al matrix alloy,the aging kinetics of the composite is obviously accelerated by the reinforcement *** T6-treated composite exhibits excellent tensile properties at both room temperature and elevated *** at 350℃,the T6-treated composite not only has a high yield strength of 121 MPa and ultimate tensile strength of 128 MPa,but also exhibits a large elongation of 11.6%.Different strengthening mechanisms of nano-AlN and submicron-Al_(2)O_(3) particles were also discussed in detail.

关键词： 6061 Al matrix composite nano-AlN particles submicron-Al_(2)O_(3)particles high-temperature strength

Grain boundary segregation induced strong UHTCs at elevated temperatures:A universal mechanism from conventional UHTCs to high entropy UHTCs

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Journal of Materials Science & Technology 2022年第28期123卷 26-33页

作者： Fu-Zhi Dai Bo Wen Yinjie Sun Yixiao Ren Huimin Xiang Yanchun Zhou Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China DP Technology Beijing 100044China

Ultra-high temperature ceramics(UHTCs)exhibit a unique combination of excellent properties,including ultra-high melting point,excellent chemical stability,and good oxidation resistance,which make them promising candidates for aerospace and nuclear ***,the degradation of hightemperature strength is one of the main limitations for their ultra-high temperature ***,searching for mechanisms that can help to develop high-performance UHTCs with good high-temperature mechanical properties is urgently *** achieve this goal,grain boundary segregation of a series of carbides,including conventional,medium entropy,and high entropy transition metal carbides,i.e.,Zr_(0.95)W_(0.05)C,TiZrHfC_(3),ZrHfNbTaC_(4),TiZrHfNbTaC_(5),were studied by atomistic simulations with a fitted Deep Potential(DP),and the effects of segregation on grain boundary strength were *** all the studied carbides,grain boundary segregations are realized,which are dominated by the atomic size *** addition,tensile simulations indicate that grain boundaries(GBs)will usually be strengthened due to *** simulation results reveal that grain boundary segregation may be a universal mechanism in enhancing the high-temperature strength of both conventional UHTCs and medium/high entropy UHTCs,since GBs play a key role in controlling the fracture of UHTCs at elevated temperatures.

关键词： UHTCs high entropy ceramics Grain boundary segregation high-temperature strength Machine learning potential

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

Enhanced high-temperature mechanical properties of laser-arc hybrid additive manufacturing of Al-Zn-Mg-Cu alloy via microstructure control

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Journal of Materials Science & Technology 2024年第2期169卷 220-234页

作者： Dehua Liu Dongjiang Wu Yunsong Wang Zhuo Chen Changrong Ge Qingyu Zhao Fangyong Niu Guangyi Ma State Key Laboratory of high-performance Precision Manufacturing Dalian University of TechnologyDalian 116024China

Recently,rapid and cost-effective additive manufacturing solutions for lightweight aluminum alloys with excellent high-temperature mechanical properties have been increasingly in *** this study,we combined laser-arc hybrid additive manufacturing with solution and artificial aging treatments to achieve Al-Zn-Mg-Cu alloy with favorable high-temperature strength via microstructure *** pores became the major defect in the as-deposited and heat-treated *** continuous distribution of eutectics with hard-brittle characteristics at the grain boundaries was destructed following heat ***-densityηprecipitates were uniformly dispersed in the heat-treated Al-Zn-Mg-Cu alloy,whereas appeared coarsened and dissolved at 473 K,owing to the rapid diffusion of Zn and *** average 0.2%yield strength(318±16 MPa)and ultimate tensile strength(362±20 MPa)at 473 K af-ter heat treatment were enhanced by approximately 58%and 51%,respectively,compared to those of the as-deposited *** addition,theηprecipitates contributed to lattice distortions and strain fields,which prevented dislocation motion and increased slip deformation resistance at high *** as-deposited specimen exhibited intergranular fracture at 473 K,with cracks preferring to propagate along the aggregated ***,crack propagation proceeded in the sections with more pores in the heat-treated *** approach may provide a valid option for achieving alu-minum alloys with excellent high-temperature mechanical properties.

关键词： Laser-arc hybrid additive manufacturing Al-Zn-Mg-Cu alloy high-temperature strength Heat treatment,Microstructure evolution

Microstructure and mechanical property evolution of friction stir welded(B4C+Al2O3)/Al composites designed for neutron absorbing materials

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Science China(Technological Sciences) 2020年第7期63卷 1256-1264页

作者： ZAN YuNing WANG BeiBei ZHOU YangTao JIA CunLei LIU ZhenYu WANG QuanZhao XIAO BoLv MA ZongYi Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

(B4C+Al2O3)/Al composite designed for the dry storage of spent nuclear fuels was fabricated and then subjected to friction stir welding, at a welding speed of 100 mm/min and rotation rates of 400–800 r/min. Sound joints were obtained under all welding parameters;however, significant softening occurred in the nugget zone(NZ) for all the joints. Therefore, all the joints exhibited significantly decreased strength at both room temperature and high temperature compared with the base metal, with the joints fracturing in the NZs. Rotation rate exhibited no obvious effect on the tensile strength of the joints, but led to increased elongation as the result of the broadened NZs. The detailed microstructural examinations indicated that the welding thermomechanical effect broke up the near 3D amorphous Al2O3 netlike structure distributed at the Al grain boundaries, caused the coarsening of Al grains, and the agglomeration and crystallization of amorphous Al2O3, thereby resulting in the softening of the NZs and the reduction in the joint strength. Consequently, inhibiting the breakup and crystallization of 3D amorphous Al2O3 netlike structure is the key factor to improve the joint strength of the(B4C+Al2O3)/Al composite.

关键词： particle reinforced Al matrix composites neutron absorber materials FSW mechanical properties high-temperature strength

Effect of Al_(2)O_(3)on the Mechanical Properties of(B_(4)C+Al_(2)O_(3))/Al Neutron Absorbing Materials

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Acta Metallurgica Sinica(English Letters) 2024年第8期37卷 1411-1420页

作者： J.X.Cai B.M.Shi N.Li Y.Liu Z.G.Zhang Y.N.Zan Q.Z.Wang B.L.Xiao Z.Y.Ma Shi‑Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Nuclear Equipment Division Beijing Institute of Nuclear EngineeringChina Nuclear Power Engineering Co.Ltd.Beijing 100840China Department of Materials Science School of Mechanical EngineeringShenyang UniversityShenyang 110044China

B_(4)C/Al composites are widely utilized as neutron absorbing materials for the storage and transportation of spent nuclear *** order to improve the high-temperature mechanical properties of B_(4)C/Al composites,in-situ nano-Al_(2)O_(3)was introduced utilizing oxide on Al powder *** this study,the Al_(2)O_(3)content was adjusted by utilizing spheroid Al powder with varying diameters,thereby investigating the impact of Al_(2)O_(3)content on the tensile properties of(B_(4)C+Al_(2)O_(3))/Al *** was found that the pinning effect of Al_(2)O_(3)on the grain boundaries could hinder the recovery of dislocations and lead to dislocation accumulation at high *** the result,with the increase in Al_(2)O_(3)content and the decrease in grain size,the high-temperature strength of the composites increased *** finest Al powder used in this investigation had a diameter of 1.4μm,whereas the resultant composite exhibited a maximum strength of 251 MPa at room temperature and 133 MPa at 350℃,surpassing that of traditional B_(4)C/Al composites.

关键词： Al matrix composites Neutron absorbing materials (B_(4)C+Al_(2)O_(3))/Al composites high-temperature strength

An overview on the novel heat-resistant ferritic stainless steels

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Tungsten 2023年第4期5卷 467-480页

作者： Yang Zhao Hou-Long Liu Liang-Liang Wei Li-Qing Chen School of Materials Science and Engineering Northeastern UniversityShenyang110819China Key Laboratory of Lightweight Structural Materials of Liaoning Province Shenyang110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang110819China

Heat-resistant ferritic stainless steels are widely used in many high-temperature applications such as power plants,automotive exhaust manifolds and solid oxide fuel cell interconnects due to their low price,low coefficient of thermal expansion,high thermal conductivity,high thermal fatigue resistance,high creep performance and excellent corrosion ***-temperature strength,formability,high-temperature oxidation resistance and creep performance are the main evaluation criteria for the *** the development of relevant industries,higher requirements are proposed for the performance of ferritic stainless ***,the development of a new generation of heat-resistant ferritic stainless steel has received extensive *** this presentation,we summarized the research progress of heat-resistant ferritic stainless steels including high-temperature strength,formability,high-temperature oxidation resistance and creep ***,some suggestions are given for alloy composition design and microstructure *** future research direction of heat-resistant ferritic stainless steels also prospected.

关键词： Ferritic stainless steel Laves phase high-temperature strength high-temperature oxidation Formability Creep performance

ADVANCED NICKEL-BASED AND NICKEL-IRON-BASED SUPERALLOYS FOR CIVIL ENGINEERING APPLICATIONS

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Acta Metallurgica Sinica(English Letters) 2005年第4期18卷 453-462页

作者： U. Brill ThyssenKrupp VDM GmbH 58791 Werdohl Germany

The use of high-temperature materials is especially important in power station construction, heating systems engineering, furnace industry, chemical and petrochemical industry, waste incineration plants, coal gasification plants and for flying gas turbines in civil and military aircrafts and helicopters. Particularly in recent years, the development of new processes and the drive to improve the economics of existing processes have increased the requirements significantly so that it is necessary to change from well-proven materials to new alloys. Hitherto, heat resistant ferritic steels sufficed in conventional power station constructions for temperatures up to 550℃ newly developed ferritic/martensitic steels provide sufficient strength up to about 600 - 620℃. In new processes, e.g. fluidized-bed combustion of coal, process temperatures up to 900℃ occur. However, this is not the upper limit, since in combustion engines, e.g. gas turbines. Material temperatures up to 1100℃ are reached locally. Similar development trends can also be identified in the petrochemical industry and in the heat treatment and furnace engineering. The advance to ever higher material temperatures now not only has the consequence of having to use materials with enhanced high-strength properties, considerable attention now also has to be given to their chemical stability in corrosive media. Therefore not only examples of the use of high-temperature alloys for practical applications will be given but also be contributed to some general rules for material selection with regard to their high-temperature strength and corrosion resistance.

关键词： nickel-based alloy high-temperature strength high-temperature corrosion resistance civil engineering application

Microstructural evolution and mechanical properties of Nb-Si-Cr ternary alloys with a tri-phase Nb/Nb5Si3/Cr2Nb microstructure fabricated by spark plasma sintering

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Progress in Natural Science:Materials International 2018年第5期28卷 626-634页

作者： Shasha Zhang Wei Liu Jiangbo Sha School of Materials Science and Engineering Beihang University Welding and Plastic Forming Division Beijing Institute of Aeronautical Materials

In this work,pure Nb,Nb;Si;and Laves Cr;Nb compound powders were used as raw materials to prepare Nb-SiCr ternary alloys by spark plasma sintering（SPS）.A comprehensive estimation of the microstructure and properties,including room temperature fracture toughness,high temperature strength and oxidation resistance,of the Nb-Si-Cr ternary alloys as a function of the Nb/Nb;Si;/Cr;Nb phase volume fraction combinations was *** results showed that Nb-Si-Cr ternary samples with the relative density larger than 98.42% were obtained by SPS processing,and the samples all consisted of Nb,Nb;Si;and Cr;Nb phases that were distributed *** fracture toughness K;of the Nb/Nb;Si;/Cr;Nb microstructure,which was dominated by the Nb phase,naturally increased with the Nb *** expected,the room-temperature Vickers hardness and the high-temperature strength of the bulk alloys increased monotonically with the increasing of the stiffening Nb;Si;***,the binary Cr;Nb phase played a positive role in the high temperature strength and oxidation ***,the fracture modes of the typical Nb/Nb;Si;/Cr;Nb microstructures under bending and compression conditions at room and high temperatures as well as the oxidation mechanism are described and discussed.

关键词： Nb-Si Alloy Spark Plasma Sintering(SPS) Phase Fraction Fracture Toughness high-temperature strength