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Chinese Journal of Aeronautics 2024年第2期37卷 524-540页

作者： Xuan CUI Rui ZHAO Min WAN School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China Jiangxi Research Institute of Beihang University Jiangxi 330000China

Electrically Assisted Forming(EAF)technology has obvious advantages in material forming.To develop an effective constitutive model considering electrical effects,room temperature and electrically assisted quasi-static uniaxial tensile tests were conducted using ultrathin nickelbased superalloy plates with a thickness of 0.25 mm.The research focused on the two most widely recognized effects:the Joule thermal and the electric athermal effects.The mechanism of current action can be divided into two scenarios:one considering the Joule thermal effect only,and the other considering both effects simultaneously.Two basic constitutive models,namely the Modified-Hollomon model and the Johnson-Cook(J-C)model,were selected to be optimized through the classification of two different situations,and four optimized constitutive models were proposed.It was found that the J-C model with simultaneous consideration of the Joule thermal effect and electric athermal effect had the best prediction effect by comparing the results of these four models.Finally,the accuracy of the optimization model was verified by finite element simulation of the electrically assisted stretching optimization model.The results show that the constitutive model can effectively predict the temperature effect caused by the Joule heat effect and the athermal effect of current on the material.

关键词： Joule heating Elastoplasticity Plastic deformation superalloys Constitutive models

Microstructure and stress rupture properties of polycrystal and directionally solidified castings of nickel-based superalloys

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International Journal of Minerals,Metallurgy and Materials 2014年第1期21卷 58-64页

作者： Bao-ping Wu Lin-han Li Jian-tao Wu Zhen Wang Yan-bin Wang Xing-fu Chen Jian-xin Dong Jun-tao Li Central Iron & Steel Material Research Institute School of Materials Science and Engineering University of Science and Technology Beijing

A new directionally solidified Ni-based superalloy DZ24, which is a modification of K24 alloy without rare and expensive elemental additions, such as Ta and Hf, was studied in this paper. The microstructure and stress rupture properties of conventionally cast and directionally solidified superalloys were comparatively analyzed. It is indicated that the microstructure of K24 alloy is composed of γ, γ＇, γ/γ＇ eutectics and MC carbides. Compared with the microstructure of K24 polycrystalline alloy, γ/γ＇ eutectic completely dissolves into the γ matrix, the fine and regular γ＇ phase reprecipitates, and MC carbides decompose to M6C/M23C6 carbides after heat treatment in DZ24 alloy. The rupture life of DZ24 alloy is two times longer than that of K24 alloy. The more homogeneous the size of γ＇ precipitate, the longer the rupture life. The coarsening and rafting behaviors of γ＇ precipitates are observed in DZ24 alloy after the stress-rupture test.

关键词： superalloys nickel alloys microstructure precipitation carbides mechanical properties

Doping effects on the stacking fault energies of the γ' phase in Ni-based superalloys

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Chinese Physics B 2020年第2期29卷 390-395页

作者：李伟节王崇愚 Department of Physics Tsinghua UniversityBeijing 100084China Institute of Applied Physics and Computational Mathematics Beijing 100088China

The doping effects on the stacking fault energies(SFEs),including the superlattice intrinsic stacking fault and superlattice extrinsic stacking fault,were studied by first principles calculation of the γ' phase in the Ni-based superalloys.The formation energy results show that the main alloying elements in Ni-based superalloys,such as Re,Cr,Mo,Ta,and W,prefer to occupy the Al-site in Ni3Al,Co shows a weak tendency to occupy the Ni-site,and Ru shows a weak tendency to occupy the Al-site.The SFE results show that Co and Ru could decrease the SFEs when added to fault planes,while other main elements increase SFEs.The double-packed superlattice intrinsic stacking fault energies are lower than superlattice extrinsic stacking fault energies when elements(except Co)occupy an Al-site.Furthermore,the SFEs show a symmetrical distribution with the location of the elements in the ternary model.A detailed electronic structure analysis of the Ru effects shows that SFEs correlated with not only the symmetry reduction of the charge accumulation but also the changes in structural energy.

关键词： stacking fault energy site preference Ni-based superalloys electronic structure

Effect of oxygen content and heat treatment on carbide precipitation behavior in PM Ni-base superalloys

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International Journal of Minerals,Metallurgy and Materials 2012年第9期19卷 827-835页

作者： Heng-san Liu Lin Zhang Xin-bo He Xuan-hui Qu Hong-min Zhu Guo-qing Zhang State Key Laboratory for Advanced Metals and Materials Beijing Key Laboratory for Powder Metallurgy and Particulate Materials University of Science and Tech-nology Beijing Beijing 100083 China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China National Key Lab of High Temperature Structural Materials Beijing Institute of Aeronautical Materials Beijing 100095 China

The influence of oxygen content and heat treatment on the evolution of carbides in a powder metallurgy （PM） Ni-base superalloy was characterized. The results reveal that oxygen content has little influence on the precipitation of carbides inside the particles. However, under the consolidated state, stable Ti oxides on the particle surface act as nuclei for the precipitation of prior particle boundaries （PPB）. Also, oxygen can diffuse internally along grain boundaries under compressive stress, which favors the precipitation of carbides inside the particles. Therefore, a higher amount of carbides will appear with more oxygen content in the case of consolidated alloys. It is also observed that PPB can be disrupted into discontinuous particles at 1200℃, but this carbide network is hard to be eliminated completely. The combined MC-M23C6 morphology approves the nucleation and growth mechanism of carbide evolution.

关键词： powder metallurgy nickel alloys superalloys oxygen heat treatment carbides precipitation

Effects of Rhenium on Creep Rupture Life of a Single Crystal superalloys

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Journal of Materials Science & Technology 1999年第1期15卷 53-57页

作者： Li, Jiarong Tang, Dingzhong Lao, Riling Liu, Shizhong Wu, Zhongtang Inst Aeronaut Mat Beijing 100095 Peoples R China

The slabs of a single crystal superalloy were poured with 2.2%Re, 3.2%Re and 4.2%Re and other element contents of the alloys were basically kept unchanged. The effects of Re on the ultimate tensile strength, creep rupture life and rafting of a single crystal superalloy were studied. The results show that with increasing Re content the ultimate tensile strength decreases but the plasticity increases at 982 degree C/248.2 MPa, 1038 degree C/206.8 MPa and 1070 degree C/176.8 MPa for the alloy; on the microstructure aspect, with increasing the creep rupture life of the alloy the rafting is getting bigger and bigger at the same test condition, and the rafting suppresses creep and increases creep rupture life in the single crystal superalloy. (Edited author abstract) 11 Refs.

关键词： superalloys

Low-Cycle Fatigue Properties of Nickel-Based superalloys Processed by High-Gradient Directional Solidification

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Acta Metallurgica Sinica(English Letters) 2017年第9期30卷 878-886页

作者： Z.D.Fan D.Wang C.Liu G.Zhang J.Shen L.H.Lou J.Zhang superalloys Division Institute of Metal ResearchChineseAcademy of SciencesShenyang 110016China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Xi'an Thermal Power Research Institute Co. Ltd.Xi'an 710054China

The low-cycle fatigue （LCF） properties of DD10 （single-crystal） and DZ53 （columnar-grained） superalloys solidified by liquid-metal cooling （LMC） and high-rate solidification （HRS） processes have been systematically investi- gated. It was found that the LCF life of DZ53 solidified by LMC was obviously better than that solidified by HRS. In contrast, for DD10, LMC showed no remarkable influences on LCF properties at high temperature and only improved LCF properties at intermediate temperature. Microstructure examination showed that the cracks generally initiated at microp- ores in the subsurface at intermediate temperature. However, the cracks occurred on the surface due to oxidation, or persistent slip bands near script-MC at high temperature. Therefore, the benefits of LMC technique can be attributed to both of the reduced casting defects which significantly affect the LCF properties at intermediate temperature and the improved microstructural homogeneity which was strongly correlated to the LCF properties of alloys at high temperature.

关键词： superalloys Rapid solidification Low-cycle fatigue Microstructure

Molecular Dynamics Simulation of Persistent Slip Bands Formation in Nickel-base superalloys

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International Journal of Automation and computing 2017年第1期14卷 68-79页

作者： Jian-Feng Huang Zhong-Lai Wang Er-Fu Yang Don McGlinchey Yuan-Xin Luo Yun Li Yi Chen School of Engineering and Built Environment Glasgow Caledonian UniversityGlasgow G4 0BAUK University of Electronic Science and Technology of China Chengdu 611731China Space Mechatronic Systems Technology Laboratory(SMe STech) Department of DesignManufacture and Engineering ManagementJames Weir BuildingUniversity of StrathclydeGlasgow G1 1X JUK College of Mechanical Engineering Chongqing UniversityChongqing 400044China School of Computer Science and Network Security Dongguan University of TechnologyDongguan 523808China

Persistent slip band （PSB） is an important and typical microstructure generated during fatigue crack initiation. Intensive work has been done to investigate the mechanisms of the formation of persistent slip bands since the 1950s when Wadsworth[1] observed the fatigue fracture in copper. Simulations have indicated that PSBs formation during fatigue crack initiation is related to the dislocation driving force and interaction. In this paper, a molecular dynamics （MD） simulation associated with embedded atom model （EAM） is applied to the PSBs formation in nickel-base superalloys with different microstructure and temperature under tensile- tensile loadings. Five MD models with different microstructure （pure 5/ phase and γ/γ＇ phase）, grain orientation （[1 0 0][0 1 0][0 0 1] and [1 1 1][1 0 1][1 2 1]） and simulation temperature （300 K, 600 K, 900 K） were built up in these simulations. Our results indicated that within the γ phase by massive dislocations, pile-up and propagation which can penetrate the grain. Also, it is found that the temperature will affect the material fatigue performance and blur PSBs appearance. The simulation results are in strong agreement with published experimental test result. This simulation is based on the work[2]. The highlights of the article include： 1） investigation of the PSB formation via molecular dynamics simulation with three different parameters, 2） conduct of a new deformation and velocity combination controlled simulation for the PSB formation, 3） high-performance computing of PSB formation, and 4） systematic analysis of the PSB formation at the atomic scale in which the dislocation plays a critical role.

关键词： Persistent slip bands （PSB） molecular dynamics superalloys computational simulation embedded atom model （EAM）.

Influences of Re on low-cycle fatigue behaviors of single crystal superalloys at intermediate temperature

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Journal of Materials Science & Technology 2019年第9期35卷 1917-1924页

作者： Liu Liu Jie Meng Jinlai Liu Mingke Zou Haifeng Zhang Xudong Sun Yizhou Zhou superalloys Division Institute of Metal ResearchChinese Academy of SciencesShenyang110016China Key Laboratory for Anisotropy and Texture o f Materials Northeastern UniversityShenyang110819China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

Low-cycle fatigue behaviors of Ni-base single crystal superalloys containing different Re contents have been investigated at 760℃. During heat treatment. Reretards γ phases coarsening and equalizes the distribution of γ' phases. As Re content increases, fatigue life increases and slip bands distribute more inhomogeneously. Moreover, adding Re not only reduces stacking fault energy of the matrix, but also promotes the element segregation to increase the lattice misfit. However, the larger lattice misfit does not lead to the formation of dislocation networks, but which activates dislocation movement and promotes dislocations cross-slip and climbing movement under high temperature and applied stress. On the other hand, with the addition of Re, cyclic deformation behaviors change from cyclic hardening to cyclic stability, mainly depending on a transformation of deformation mechanisms from slip bands cutting through γ and γ' phases to stacking faults shearing.

关键词： Single crystal superalloys Low-cycle fatigue Deformation behaviors Deformation mechanisms

Activity coefficients of NiO and CoO in CaO–Al_2O_3–SiO_2 slag and their application to the recycling of Ni–Co–Fe-based end-of-life superalloys via remelting

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International Journal of Minerals,Metallurgy and Materials 2017年第1期24卷 25-36页

作者： Xin Lu Takahiro Miki Tetsuya Nagasaka Graduate School of Engineering Tohoku University

To design optimal pyrometallurgical processes for nickel and cobalt recycling, and more particularly for the end-of-life process of Ni-Co-Fe-based end-of-life（EoL） superalloys, knowledge of their activity coefficients in slags is essential. In this study, the activity coefficients of NiO and CoO in CaO-Al_2O_3-SiO_2 slag, a candidate slag used for the EoL superalloy remelting process, were measured using gas/slag/metal equilibrium experiments. These activity coefficients were then used to consider the recycling efficiency of nickel and cobalt by remelting EoL superalloys using CaO-Al_2O_3-SiO_2 slag. The activity coefficients of NiO and CoO in CaO-Al_2O_3-SiO_2 slag both show a positive deviation from Raoult＇s law, with values that vary from 1 to 5 depending on the change in basicity. The activity coefficients of NiO and CoO peak in the slag with a composition near B =（%CaO）/（%SiO_2） = 1, where B is the basicity. We observed that controlling the slag composition at approximately B = 1 effectively reduces the cobalt and nickel oxidation losses and promotes the oxidation removal of iron during the remelting process of EoL superalloys.

关键词： recycling nickel cobalt end-of-life superalloys activity coefficients remelting slag

New approach for assessing the weldability of precipitation-strengthened nickel-base superalloys

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International Journal of Minerals,Metallurgy and Materials 2013年第12期20卷 1183-1191页

作者： Homam Naffakh Moosavy Mohammad-Reza Aboutalebi Seyed Hossein Seyedein Meisam Khodabakhshi Carlo Mapelli School of Metallurgy and Materials Engineering Iran University of Science and Technology (IUST) MAPNA Turbine Engineering and Manufacturing Company (TUGA) Dipartimento di Meccanica Politecnico di Milano

A new procedure was proposed for evaluating the weldability of nickel-base superalloys. The theory is on the basis of two microstructural patterns. In pattern I, the weld microstructure exhibits severe alloying segregation, many low-melting eutectic structures, and low weldability. The weld requires a weaker etchant and a shorter time for etching. In pattern Ⅱ, the weld microstructure displays less alloying segregation, low quantity of eutectic structures, and high weldability. The weld needs a stronger etchant and a longer time for etching. Five superalloys containing different amounts of Nb and Ti were designed to verify the patterns. After welding operations, the welds were etched by four etchants with different corrosivities. The weldability was determined by TG-DSC measurements. The metallography and weldability results confirmed the theoretic patterns. Finally, the etchant corrosivity and etching time were proposed as new criteria to evaluate the weldability of nickel-base superalloys.

关键词： superalloys nickel alloys weldability metallography etching segregution eutectics