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SSRN 2023年

作者： Su, Ru Li, Jixiao Wu, Dayong Hu, Fuhong Liang, Xueze Shen, Qingyuan Tian, Wenguang Wang, Yalong Ma, Haikun Narayanaswamy, Balaji Dong, Huicong Wang, Qian Hebei Key Laboratory of Material Near-Net Forming Technology School of Materials Science and Engineering Hebei University of Science and Technology Shijiazhuang050018 China Oriental Bluesky Titanium Technology Co. Ltd Yantai264670 China China Astronautics Standards Institute Beijing100071 China School of Engineering Deakin University Geelong Australia State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing100083 China

This study aims to present the optimum technological parameters of hot forging process of aerospace bolt. Deformation Temperature and strain rate were determined according to relevant conditions for commercial bolt production. Deformation behavior and evolution of microstructure of Waspaloy were investigated using hot isothermal compression tests. The results show that the flow stresses show sufficient sensitivity to the deformation parameters and decreased with increase in deformation temperatures and decrease in strain rates. At high strain rates of 5-10 s-1. Flow curves exhibit a pronounced flow softening. At low strain rates of 0.01-0.1 s-1, the curves demonstrate a dynamic equilibrium. Constitute models of Waspaloy is established and the hot deformation energy is calculated as 446.824 kJ/mol. Microstructures showed that at low temperature (1000-1040°C), grain refinement of DRX is the main mechanism of microstructural evolution, while grain growth kinetics is the dominant mechanism at high temperature (1080-1120°C). DRX kinetics model of this superalloy is established. Also, constitutive and dynamic recrystallization models are brought into the Deform-3D software for validation. The results reveal that the simulation results match well with the experimental results. The study can provide guidance on optimizing technological parameters and predict the microstructure for commercial bolt forging. © 2023, The Authors. All rights reserved.

关键词： Finite element method

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Nucleation and Growth Mechanisms of Ferrite on Mg-Ti-Oxides Surface: First-Principles Investigation

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SSRN 2023年

作者： Liu, Er-Kang Wang, Qi Guo, Zhi-Hong Wang, Li-Jun Chang, Xi-Wang Zheng, Ya-Xu Ma, Chenyu Chen, Zhen-Ye Wang, Bo Zhu, Li-Guang Hebei Key Laboratory of Materials Near-Net Forming Technology School of Materials Science and Engineering Hebei University of Science and Technology Shijiazhuang050018 China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing100083 China Institute of Energy and Power Innovation North China Electric Power University Beijing102206 China HBIS Material Technology Research Institute Shijiazhuang050000 China

Fine and dispersed Mg-Ti-oxide inclusions, which act as heterogeneous nucleation sites for intragranular ferrite, have been acknowledged as an effective method for grain refinement. In this paper, the nucleation and growth mechanisms of ferrite on Mg-Ti-oxides surface were investigated through first-principles calculations and solid-state pressure bonding experiments. The calculated results show that the formation of cation vacancies is the limiting step for Mn solute atom absorption by Mg-Ti-oxides. As determined by the lower covalency and ionicity of the Mg-O bond compared to the Ti-O bond in Mg-Ti-oxides, Mn atoms will be efficiently absorbed by occupying the Mg vacancies. The experimental results demonstrate that MgTiO3 with the maximum Mn-depleted zone (MDZ) width is the most effective for ferrite nucleation, which is consistent with the calculation results. As a representative, the Fe(110)/MgTiO3(001) interface with the lowest planar disregistry (3.16%) was selected to analyze growth behaviors. Due to charge accumulation and variation, Fe atoms are more likely to gather on the Mg-O terminal MgTiO3(001) surface and form [(Mg-O)-Fe]-1 interfaces. Its adhesion work and interface energy are 1.74 and 2.46 J/m2, respectively. The present study illustrates the nucleation and growth mechanisms of ferrite on Mg-Ti-oxides, providing theoretical support for the application of Mg-Ti-oxide inclusions in oxide metallurgy. © 2023, The Authors. All rights reserved.

关键词： Ferrite

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Atomic Simulations on the Deformation Mechanisms in Nano-Crystalline Ni-Based Superalloy Based on Grain Size, Temperature and Strain Rate

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SSRN 2022年

作者： Dong, Huicong Xu, Tianhao Ning, Tianyang Liu, Meng Wu, Dayong Ma, Haikun Feng, Zhihao Narayanaswamy, Balaji Su, Ru Hebei Key Laboratory of Material Near-net Forming Technology Hebei Engineering Laboratory of Aviation Lightweight Composite Materials and Processing Technology School of Materials Science and Engineering Hebei University of Science and Technology Hebei Shijiazhuang050000 China AVIC Shangda Superalloy Materials Co. Ltd Hebei Xingtai054800 China School of Engineering Deakin University Geelong Australia

Molecular Dynamic (MD) simulations were used to investigate the tensile properties of nanocrystalline Ni-based superalloy at different grain sizes (6.54~20 nm), temperatures (300~1000 K) and strain rates (1×107~1×109 s-1). Results indicate that plastic deformation of nanocrystalline Ni-based superalloy was governed by stacking faults and FCC-to-HCP martensitic phase transformation, which was significantly different from twinning-dominated plastic deformation in nanocrystalline Ni. Nevertheless, the conventional Hall-Petch breakdown occurred at a critical grain size in both nanocrystalline Ni and Ni-based superalloy. Moreover, flow stress and Young’s modulus were both strongly affected by temperature and strain rate. Furthermore, an increase in temperature can accelerate GB diffusion and GB migration. And, GB diffusion and GB migration were the main plastic deformation mechanisms at higher strain rates. The current study provides an atomic perspective on the deformation process and mechanisms in nanocrystalline Ni-based superalloy, as well as new perspectives on designing novel superalloys with excellent mechanical properties. © 2022, The Authors. All rights reserved.

关键词： Strain rate

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Enhancing microstructural properties of alumina ceramics via binary sintering aids

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Journal of Central South University 2021年第12期28卷 3705-3713页

作者： HU Yan-jun YIN Zi-qiang GONG Yu-bo YANG Zhi-gang YANG Zhan-ping LIANG Yin-chun DONG De-jun ZHAO Jin-jin School of Materials Science and Engineering Hebei Key Laboratory of Material Near Net Forming TechnologyHebei University of Science and TechnologyShijiazhuang 050018China School of Materials Science and Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China Institute of Materials for Energy Conversion Shijiazhuang Tiedao UniversityShijiazhuang 050043China Nantong ZhuhaiKunming Cellulose Fibers Company Technical CenterNantong 226008China

Alumina ceramics are widely used in many fields such as cutting tools,laser shock materials,roadbed board and ***,Al_(2)O_(3)ceramics are prepared by a low-cost pressureless sintering technology,using the binary sintering aids of MgO and SiO_(2).The effects of sintering temperature and the ratio of binary sintering aids on the mechanical properties and microstructure of Al_(2)O_(3)ceramics are investigated.A spinel second phase(MgAl_(2)O_(4))is found out by the analysis of the results of XRD and EDS when MgO and SiO_(2)are introduced in the *** optimum properties are found when MgO content is 20 wt.%based on the total sintering aids and the sintering temperature is 1550℃.The bending strength and the bulk density reach a maximum value of 314 MPa and 3.73 g/cm^(3),*** addition of appropriate amount of SiO_(2)makes the formation of liquid phase sintering and the removal of large ***,a small amount of magnesium oxide doping has an effect on the grain refinement from the microstructure of the ***,it is believed that MgO and SiO_(2)are the ideal sintering aids for promoting the densification and property of alumina ceramics.

关键词： alumina ceramics binary sintering aids mechanical properties microstructure

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Study on Hot Deformation Behavior of Cold-Drawn State Waspaloy and Optimization of Upsetting Process for Bolts

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SSRN 2022年

作者： Su, Ru Li, Jixiao Wang, Qian Hu, Fuhong Liang, Xueze Shen, Qingyuan Tian, Wenguang Wang, Yalong Ma, Haikun Narayanaswamy, Balaji Wu, Dayong Hebei Key Laboratory of Material Near-Net Forming Technology School of Materials Science and Engineering Hebei University of Science and Technology Shijiazhuang050018 China Oriental Bluesky Titanium Technology Co. LTD Yantai264670 China China Astronautics Standards Institute Beijing100071 China School of Engineering Deakin University Geelong Australia State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing100083 China

Mechanical performance of hot forging aviation bolt is strongly related to microstructures and deformation behaviors during hot processing. In order to determine the optimal technological parameters of Waspaloy alloy hot heading bolt, deformation behavior and microstructural evolution of Waspaloy were systematically studied. The experimental design (hot compression) is based on the actual production process parameters. The results from the strain-stress curves showed that there was an obvious flow softening with the decrease of temperature or the increase of strain rate, which can be attribute to the DRX mechanism. A dramatic yield drop was found with the temperature ranging from 1000°C to 1120°C at 1 s-1 due to the short-range ordering of phase forming elements (Ti and Al). Microstructures showed that high temperature and low strain rate promoted DRX behavior, but led to rapid grain growth, which was not conducive to the formation of uniform and fine DRX grains. DRX kinetics model of this superalloy was established based on the experimental results. Furthermore, the developed models were applied in the finite element simulation method (FEM). Combined with microstructure observation, "dead zone" of the bolt was prone to abnormal grain growth, resulting in mixed crystals and reducing the service life of the bolt. The calculated results in terms of grain sizes conform well to experimental ones, which implies a good application prospect of the theoretical calculation. With the two models, an optimization technology was put forward which could predict the microstructures in the aim of high fraction of DRX and fine DRX grains for Waspaloy during the bolt heading process. This study can provide guidance on commercial bolt heading process. © 2022, The Authors. All rights reserved.

关键词： Finite element method

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Effects of Fe Content on the 3d Morphology of Fe-Rich Phase Particles and Mechanical Properties of Cast Al-Mg-Si Alloy

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SSRN 2024年

作者： Cai, Yuehua Song, Dongfu Zhao, Yuliang Yang, Dongyang Zhang, Datong Zhang, Weiwen National Engineering Research Center of Near-net-shape Forming for Metallic Materials South China University of Technology Guangzhou510640 China Guangdong Haomei New Material Co. Ltd. Qingyuan511500 China Guangdong Provincial Key Laboratory of Metal Toughening Technology and Application Institute of New Materials Guangdong Academy of Sciences Guangzhou510650 China School of Mechanical Engineering Dongguan University of Technology Dongguan523808 China

Fe is a common impurity element in recycled aluminum scraps, and optimizing Fe content can effectively promote the effective utilization of recycled aluminum. In this study, Al-Mg-Si-Mn-Fe alloys with different Fe contents were obtained by adding various content of aluminum scraps. Synchrotron X-ray tomography technology was used to study the evolution of morphology of Fe-rich phases and corresponding effect on mechanical properties in the alloys. The results showed that as the Fe content increased, the morphology of Fe-rich phases changed from fine Chinese-script and needle-like shapes to coarse Chinese-script structure. The 3D morphology of Fe-rich phases was mainly composed of thin platelets with curved branches. The increase in Fe content did not significantly change the 3D structure of Fe-rich phases, but increased the volume fraction and volume ratio of large Fe-rich phases. When the Fe content reached 0.35%, the maximum volume of individual particles increased by 182.9% compared with the 0.2Fe alloy, and the number of branches increased by 142.2%. With the increase of Fe content, the ductility of alloys gradually decreased, especially when the Fe content exceeded 0.25%. The Fe content had a small effect on the liquidus temperature of alloys, but it changed the initial formation temperature and type of Fe-rich phases. When the Fe content exceeded 0.32%, it promoted the formation of β-Fe phase, which may be the main reason for the significant decrease in ductility of alloys with higher Fe content. © 2024, The Authors. All rights reserved.

关键词： Aluminum alloys

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Constructing Multilevel Structure with Microdomains of Oxides on Three-Dimensional High-Entropy Alloy Support Toward Efficient Oxygen Evolution

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SSRN 2022年

作者： Zhang, Shaofei Guo, Jing Li, Tiantian Sun, Jinfeng Meng, Yongqiang Kang, Jianli Tan, Linli Zhang, Zhijia Hebei Key Laboratory of Flexible Functional Materials Hebei Key Laboratory of Material Near-Net Forming Technology School of Materials Science and Engineering Hebei University of Science and Technology Shijiazhuang050018 China Key laboratory of Advanced Ceramics and Machining Technology Ministry of Education School of Materials Science and Engineering Tianjin University Tianjin300072 China Key Laboratory of Green Manufacturing of Super-light Elastomer Materials of State Ethnic Affairs Commission College of Intelligent systems Science and Technology Hubei Minzu University Enshi445000 China State Key Laboratory of Separation Membrane and Membrane Process Tianjin Municipal Key Laboratory of Advanced Fibers and Energy Storage School of Materials Science and Engineering Tiangong University Tianjin300387 China

High-entropy alloys (HEAs) with maximized configurational entropy has shown a great promise for anodic water splitting, but still limited to their unsatisfactory configuration and large-scaled application. In the present study, a series of dual-phase electrodes with spinel MnCr2O4 microdomains pinning on large-scaled and flexible surface oxidized high-entropy alloys (O-HEA) as highly efficient electrocatalysts is prepared by combining modified non-solvent induced phase separation (NIPs) and metallurgy approaches. The precipitation of MnCr2O4 microdomains from O-HEA support not only result in a shrinking of lattice constant of HEA but also lead to a surface reconstruction. Besides, the MnCr2O4 microdomains can synergy with reconstructed O-HEA support to increase the hydrophilic property and provide high-efficient electron/ion transport, thus promoting the O-O coupling. By virtues of the multilevel structure, the O-HEA2 electrode exhibits impressive oxygen evolution properties with a low overpotential of 268 mV and Tafel slope of 51.6 mV dec−1 in 1M KOH at 10 mA cm−2. It also exhibits a long durability exceed 70 h at 25 mA cm−2. This work provides a new prospect for the rational design of large-scaled and self-supported 3D HEA based electrodes for energy conversion applications. © 2022, The Authors. All rights reserved.

关键词： Catalyst activity

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Effect of Ti Particles on Microstructure and Mechanical Properties of Mg–9al–1zn Based Composite Sheets

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SSRN 2023年

作者： Xu, Jun Chen, Xudong Zheng, Kaihong Li, Xintao Wang, Tianguo Han, Shengli Kang, Yuehua Feng, Bo Yang, Hong Zhou, Nan Zhang, Weiwen Pan, Fusheng School of Material Science and Engineering Hubei University of Automotive Technology Shiyan442000 China Guangdong Provincial Key Laboratory of Metal Toughening and Application Institute of New Materials Guangdong Academy of Sciences Guangzhou510650 China National Engineering Research Centre of Near-net-shape Forming for Metallic Materials South China University of Technology Guangzhou510641 China National Engineering Research Center for Magnesium Alloys College of Materials Science and Engineering Chongqing University Chongqing400044 China

In this work, stir casting combined with ball milling process were used to produce AZ91 alloys reinforced with 1 wt%, 2 wt%, and 3 wt% Ti particles. The results of the tensile test demonstrated that the Ti particles could improve the mechanical properties of the AZ91 alloy sheets. With the addition of Ti particles, the grain size of the composite material was refined, and the texture strength decreased. Due to the interfacial reaction between Ti and Al, the formation of β-phase (Mg17Al12) was inhibited. The growth of recrystallization grains was also restrained by Ti particles. Strong interfacial reaction was observed at the Ti/Mg interface. Compared to the AZ91 sheet, 2Ti/AZ91 composite sheet had high yield strength and elongation, exhibited good comprehensive mechanical properties. These main reasons were grain refinement, texture weakening, and a mismatched coefficient of thermal expansion (CTE). © 2023, The Authors. All rights reserved.

关键词： Grain refinement

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Effect of B Addition on the Formation of Fe-Rich Phases in Al-Si-Fe Alloys

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SSRN 2022年

作者： Song, Dongfu Zhao, Yuliang Jia, Yiwang Huang, Guangyao Zhang, Zhibo Zhou, Nan Li, Xintao Zheng, Kaihong Fu, Yanan Zhang, Weiwen Guangdong Provincial Key Laboratory of Metal Toughening Technology and Application Institute of New Materials Guangdong Academy of Sciences Guangzhou510650 China National Engineering Research Centre of Near-net-shape Forming for Metallic Materials South China University of Technology Guangzhou510641 China Neutron Scattering Technical Engineering Research Centre School of Mechanical Engineering Dongguan University of Technology Dongguan523808 China Jiangxi Universal New Material Technology Co. Ltd Shangrao334499 China Shanghai Synchrotron Radiation Facility Shanghai Advanced Research Institute CAS Shanghai201204 China

Boron (B) is an effective grain refiner in Al-Si alloys, but the modification mechanism of B on the formation and solidification behaviour of Fe-rich phases is still in debate. In this paper, we used in situ synchrotron X-ray radiography, combined with thermodynamics and first-principles calculations, to study the influence of B on the evolution and solidification behaviour of microstructure of Fe-rich phases in Al-7Si-xFe (x=1.2~3.0) alloys. The results showed that B had an excellent influence on the refinement of α-Al grains in Al-7Si-1.2Fe alloys, but it had no obvious effect on the morphology and distribution of Fe-rich phases due to the eutectic reaction to form Al-AlB 2 . B had a certain refining effect on primary Fe-rich phases in Al-Si-Fe alloys with high Fe content (≥2.36 wt.%), but it did not totally prevent the formation of these phases. The results of in situ synchrotron X-ray radiography showed that the addition of B significantly reduced the formation temperature of primary Fe-rich phases. The first-principles calculations showed that the adsorption energy of B on the surface of α-Al 2 O 3 (0001) was significantly higher than that of Fe, which inhibited the nucleation of the primary Fe-rich phase above the Al-AlB 2 eutectic temperature and promoted its supercooling of nucleation. Furthermore, many α-Al nuclei formed during the transition to the Al-AlB 2 eutectic;their subsequent growth hindered the development of the primary iron-rich phase. These were the main reasons for the refinement of the primary Fe-rich phases. The results of this study provide insights for designing recycled Al-Si alloys and fundamental knowledge of Fe-rich phase modification by B addition. © 2022, The Authors. All rights reserved.

关键词： Silicon alloys

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Cover Feature:N-PType Charge Compensatory Synergistic Effect for Schottky and Efficient Photoelectrocatalysis Applications: Doping Mechanism in (Nb/Re)@WS2/Graphene Heterojunctions (Chem. Eur. J. 2/2025)

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Chemistry – A European Journal 2025年第2期31卷

作者： Zhonghao Zhou Wei Qi Zhi Li Li Yang Zhichao Lin Renguo Guan School of Material Science and Engineering Engineering Research Center of Continuous Extrusion Ministry of Education Dalian Jiaotong University Dalian 116028 China School of Materials and Metallurgy University of Science and Technology Liaoning Anshan 114051 China College of Material Engineering Fujian Agriculture and Forestry University Fuzhou 350108 China Key Laboratory of Near-Net Forming of Light Metals of Liaoning Province Dalian Jiaotong University Dalian 116028 China

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