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Acta Metallurgica Sinica(English Letters) 2024年第2期37卷 283-292页

作者： Yong-Chao Gai Rui Zhang Chuan-Yong Cui Zi-Jian zhou yi Tan yi-zhou zhou Xiao-Feng Sun Key Laboratory of Materials Modification by Laser Ionand Electron Beams(Ministry of Education)School of Materials Science and EngineeringDalian University of TechnologyDalian116024China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

The hot compression behavior and tensile strength after compression of a new Ni-Co-based superalloy produced using electron beam smelting layered(EBSL)solidification technology were investigated.Isothermal compression tests were performed at temperatures of 1120℃and 1150℃,with strain rates of 1 s^(-1) and 0.01 s^(-1),reaching a true strain of 0.51.Tensile strength was evaluated at room temperature.The results revealed that this EBSL technology accelerates dynamic recrystallization(DRX),without compromising the strength of alloy.A significant correlation between the volume fraction of DRX and the strain rate was observed,with higher fractions at lower strain rates,leading to higher tensile strength.Additionally,at the same strain rate,the specimens compressed at 1120℃exhibited higher tensile strength due to undissolvedγ′precipitates.After solution and aging heat treatment,the alloy maintained high tensile strength.The results suggested that the EBSL Ni-Co-based superalloy offers excellent prospects for practical applications.

关键词： Ni-Co-based superalloy Hot deformation Electron beam smelting Tensile strength

Effects of Ag addition on the microstructures and properties of Al–Mg–Si–Cu alloys

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International Journal of Minerals,Metallurgy and Materials 2018年第1期25卷 62-72页

作者： Li-zi He yi-heng Cao yi-zhou zhou Jian-zhong Cui Key Lab of Electromagnetic Processing of Materials Ministry of EducationNortheastern University School of Materials Science and Engineering Northeastern University Institute of Metal Research Chinese Academy of Sciences

Effects of Ag addition on the microsmactures, aging characteristics, tensile properties, electrochemical properties, and intergranu- lar corrosion （IGC） properties of Al 1.1Mg-0.8Si-0.9Cu-0.35Mn4）.02Ti alloy were investigated using scanning electronic microscopy and transmission electronic microscopy. The aging process of Al-Mg-Si-Cu alloys was accelerated by the addition of Ag. The strength of peak-aged Al-Mg-Si-Cu alloys was enhanced by Ag addition because of the high density of β＂- and L-phase age-hardening precipitates. The corrosion performance of the Al-Mg-Sii-Cu alloy is closely related to the aging conditions and is independent of the Ag content. The IGC susceptibility is serious in the peak-aged alloy because of the continuous distribution of Cu-rich Q-phase precipitates along grain boun- daries. Ag addition reduces the size of the grain-boundary-precipitate Q phase and the width of the precipitate-free zone and thus results in decreased IGC susceptibility of Al-Mg-Si Cu alloys.

关键词： Al-Mg-Si-Cu alloys silver addition aging tensile properties corrosion properties microstructures

Effects of Crystal Orientations on the Low-Cycle Fatigue of a Single-Crystal Nickel-Based Superalloy at 980 °C

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Acta Metallurgica Sinica(English Letters) 2019年第3期32卷 381-390页

作者： Liu Liu Jie Meng Jin-Lai Liu Hai-Feng Zhang Xu-Dong Sun yi-zhou zhou School of Materials Science and Engineering Northeastern University Superalloys Division Institute of Metal Research Chinese Academy of Sciences Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences

The influence of crystal orientations on the low-cycle fatigue(LCF) behavior of a 3Re-bearing Ni-based single-crystal superalloy at 980 °C has been investigated. It is found that the orientation dependence of the fatigue life not only depends on the elastic modulus, but also the number of active slip planes and the plasticity of materials determine the LCF life,especially for the [011] and [111] specimens. The [011] and [111] specimens with better plasticity withstand relatively concentrated inelastic deformation caused by fewer active slip planes, compared to the [001] specimens resisting widespread deformation caused by a higher number of active slip planes. Additionally, fatigue fracture is also influenced by cyclic plastic deformation mechanisms of the alloy with crystal orientations, and the [001] specimens are plastically deformed by wave slip mechanism and fracture along the non-crystallographic plane, while the [011] and [111] specimens are plastically deformed by planar slip mechanism and fracture along the crystallographic planes. Moreover, casting pores,eutectics, inclusions and surface oxide layers not only initiate the crack, but also reduce the stress concentration around crack tips. Our results throw light upon the effect of inelastic strain on the LCF life and analyze the cyclic plastic deformation for the alloy with different orientations.

关键词： Single-crystal superalloy Low-cycle fatigue Anisotropy Fracture behavior

Effects of Substrate Crystallographic Orientations on Microstructure in Laser Surface-Melted Single-Crystal Superalloy:Theoretical Analysis

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Acta Metallurgica Sinica(English Letters) 2016年第8期29卷 763-773页

作者： Guo-Wei Wang Jing-Jing Liang yi-zhou zhou Tao Jin Xiao-Feng Sun Zhuang-Qi Hu Institute of Metal Research Chinese Academy of Sciences School of Materials Science and Engineering University of Science and Technology of China

A geometric analysis technique for crystal growth and microstructure development in single-crystal welds had been previously developed.And the effect of welding conditions on the tendency of stray grains formation during solidification was researched.In the present work,these analytical methods were further extended.Combined with an original vectorization method,a 3D Rosenthal solution was used to determine thermal conditions of the welds.Afterward,the dendrite growth orientation,the dendrite growth velocity and the thermal gradient along dendrite direction were calculated and lively plotted.Finally,the tendency of stray grains formation in the solidification front was forecasted and its distribution was presented with a 3D plot.The results indicate that substrate orientation has some impacts on the crystal growth pattern,dendrite growth velocity,distribution of thermal gradient and stray grain.Based on the research methods proposed in this work,any substrate crystallographic orientation can be studied,and predicted stray grains distribution can be visualized.

关键词： Single crystal Laser surface remelting Weld repair Modeling Stray grains distribution

Effect of Orientation on Stress-Rupture Property and Related Deformation Microstructure of a Ni-Base Re-containing Single-Crystal Superalloy at 900℃

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Acta Metallurgica Sinica(English Letters) 2021年第5期34卷 719-728页

作者： Guang-Lei Wang Jin-Lai Liu Ji-De Liu yi-zhou zhou Xu-Dong Sun Hai-Feng Zhang Xiao-Feng Sun School of Materials Science and Engineering Northeastern UniversityShenyang110004China Institute of Metal Research Chinese Academy of SciencesShenyang110016China

Stress-rupture properties of a Ni-base Re-containing single-crystal superalloy with three orientations have been tested under 900℃/445 MPa.An obvious anisotropy of stress-rupture property is attributed to orientation reliant deformation microstructure.The good strength in[001]orientation is attributed to the rapid multiplication of dislocations active in horizontal channels and laterγ'cutting via dislocations pair coupled with anti-phase boundary.The microtwin formation largely limits the strength and plasticity as a result of the continuous shearing acrossγ/γ'microstructure by{111}112 slip activated in[011]orientation.The property in[111]orientation results mainly from the lateral cross-slip movements of the screw dislocations within connected matrix channels as well as the precipitate shearing by coplanar dislocations.Microcracks all initially originate from the interdendritic micropores in three orientations.The critical temperature of stress-rupture anisotropy could be increased by a high level of refractory solutes especially Re.

关键词： Nickel-base superalloy Stress-rupture property Orientation effec Deformation microstructure Fracture behavior

Phase constitution,microstructure and mechanical properties of a Ni-based superalloy specially designed for additive manufacturing

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China Foundry 2021年第4期18卷 397-408页

作者： Bin Wu Jing-jing Liang Yan-hong Yang Jin-guo Li yi-zhou zhou Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Space Manufacturing Technology(CAS Key Lab) Beijing 100094China

In this study,a kind of Ni-based superalloy specially designed for additive manufacturing(AM)was investigated.Thermo-Calc simulation and differential scanning calorimetry(DSC)analysis were used to determine phases and their transformation temperature.Experimental specimens were prepared by laser metal deposition(LMD)and traditional casting method.Microstructure,phase constitution and mechanical properties of the alloy were characterized by scanning electron microscopy(SEM),transmission scanning electron microscopy(TEM),X-ray diffraction(XRD)and tensile tests.The results show that this alloy contains two basic phases,γ/γ’,in addition to these phases,at least two secondary phases may be present,such as MC carbides and Laves phases.Furthermore,the as-deposited alloy has finer dendrite,its mean primary dendrite arm space(PDAS)is about 30-45μm,and the average size ofγ’particles is 100-150 nm.However,the dendrite size of the as-cast alloy is much larger and its PDAS is 300-500μm with secondary and even third dendrite arms.Correspondingly,the alloy displays different tensile behavior with different processing methods,and the as-deposited specimen shows better ultimate tensile stress(1,085.7±51.7 MPa),yield stress(697±19.5 MPa)and elongation(25.8%±2.2%)than that of the as-cast specimen.The differences in mechanical properties of the alloy are due to the different morphology and size of dendrites,γ’,and Laves phase,and the segregation of elements,etc.Such important information would be helpful for alloy application as well as new alloy development.

关键词： additive manufacturing laser metal deposition Ni-based superalloy tensile behavior

Amelioration of weld-crack resistance of the M951 superalloy by engineering grain boundaries

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Journal of Materials Science & Technology 2021年第19期78卷 260-267页

作者： Mingyue Wen Yuan Sun Jinjiang Yu Shulin Yang Xingyu Hou Yanhong Yang Xiaofeng Sun yi zhou zhou Shi-changxu Innovation Center for Advanced Materials Institute of Metal Research.Chinese Academy of SciencesShenyang110016China School of Materials Science and Engineering.University of Science and Technology of China Shenyang110016China Shenyang Liming Aeroengine Cooperation Ltd Shenyang110043China

Fusion weld is a portable and economical joining and repairing method of metals.However,weld cracks often occur during the fusion weld of Ni-base superalloys,which hinder the applications of fusion weld on this kind of materials.In this work,the effects of microstructures of grain boundaries(GBs)of the prototype M951 superalloy on its weldability were investigated.The precipitated phases,the elemental segregations on GBs,and the morphologies of GBs can be largely altered by regulating the cooling rates of pre-weld heat treatments.With decreasing the cooling rate,chain-like M_(23)X_(6)phase precipitates along the GBs,accompanying segregations of B,and GBs becomes more serrated in morphology.During fusion weld,the engineered GBs in the M951 superalloy with a low cooling rate favor the formation of the continuous liquid films on GBs,which together with the serrated GB morphology significantly prevents the formation of weld cracks.Our findings imply that the weld-crack resistance of the superalloys can be ameliorated by engineering GBs.

关键词： Fusion weld Superalloys M951 Weld-crack resistance Grain boundary engineering

Effect of High Density Current Pulses on Microstructure and Mechanical Properties of Dual-Phase Wrought Superalloy

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Acta Metallurgica Sinica(English Letters) 2021年第12期34卷 1635-1644页

作者： Jun Zhang Ji-De Liu Xin-Fang Zhang Chuan-Yong Cui Jin-Guo Li yi-zhou zhou Bao-Quan Wang Jing-Dong Guo State Key Laboratory of Advanced Metallurgy School of Metallurgical and Ecological EngineeringUniversity of Science and Technology BeijingBeijing 100083China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

In this study,high density electric current pulse(ECP)treatment was introduced instead of the conventional solution treatment,and theγ′phase was completely dissolved under the ECP treatment within only several milliseconds at 1148°C.Due to the extremely short treatment time and high cooling rate,the growth ofγ-phase matrix grain andγ′phase precipitate was effectively retarded.By comparing with the conventional heat process,the grain size of ECP treated sample was controlled to about 15μm,the size of the re-precipitatedγ′phase reduced from 65 to 35 nm,and the number density ofγ′precipitate increased from 1.46×108 to 3.03×108/mm2.The Vickers hardness,ultimate tensile strength and yield strength of the ECP treated sample were significantly improved.According to the theoretical derivation of kinetics,the ECP treatment introduces an extra electrical free energy which promoted the dissolution ofγ′phase.The ECP treatment may provide a new method for solution treatment of the Ni-based superalloy.

关键词： Electric current pulse Superalloys Precipitation Grain size Mechanical properties

Microstructures and Mechanical Properties of a Newly Developed Austenitic Heat Resistant Steel

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Acta Metallurgica Sinica(English Letters) 2019年第4期32卷 517-525页

作者： Peng Liu Zhao-Kuang Chu Yong Yuan Dao-Hong Wang Chuan-Yong Cui Gui-Chen Hou yi-zhou zhou Xiao-Feng Sun Institute of Metal Research Chinese Academy of Sciences School of Materials Science and Engineering University of Science and Technology of China Xi'an Thermal Power Research Institute Co.Ltd. Jiangsu Feiyue Pump Group Co.Ltd.

The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.

关键词： Austenitic heat resistant steel Microstructure Mechanical property Fracture mode

Effect of Interactions Among Elements on Diffusion Process Associated with γ′ Coarsening in a Ni-Based Single-Crystal Superalloy

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Acta Metallurgica Sinica(English Letters) 2020年第7期33卷 1013-1020页

作者： Guang-Lei Wang Dong-Qing Qi Ji-De Liu Jin-Lai Liu yi-zhou zhou Xu-Dong Sun Hai-Feng Zhang Xiao-Feng Sun School of Materials Science and Engineering Northeastern UniversityShenyang 110004China Superalloys Division Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Coarsening of cuboidal γ’ precipitates and relevant diffusion process in Ni-based single-crystal superalloy CMSX-4 were investigated at 1000,1020 and 1040℃ for specific times.The y’ coarsening kinetics followed a cubic rate law with time and was presumably controlled by bulk diffusion of elements in y matrix.The associated diffusion activation energy was experimentally determined to be about 300 kJ/mol when it is considered the temperature-dependent thermo-physical parameters in modified Lifshitz-Slyozov-Wagner theory.The influence of temperature on γ/γ’ microstructure is briefly discussed based on pseudo-binary [Ni]-[Al] phase diagram.Interactions among elements can effectively raise the local vacancy formation and vacancy-atom exchange barriers close to γ-and γ’-partitioning elements,respectively.Thus,it can significantly reduce the inter-coupling migrations of atoms during the macroscopic cross-diffusion process associated with γ’ coarsening of Ni-based superalloys.

关键词： superalloy microstructure diffusion