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SSRN 2022年

作者： Liu, Fei Zhao, Haidong Zhong, Yan Jiang, Yuanhang Li, Xiang Chen, Bo Zheng, Huiting National Engineering Research Center of Near-net Shape Forming for Metallic Materials South China University of Technology Guangzhou510641 China Key Laboratory of Advanced Civil Engineering Materials Ministry of Education School of Materials Science and Engineering Tongji University Shanghai201804 China Shanghai Highway Investment Construction and Development Co. Ltd. Shanghai200336 China London Centre for Nanotechnology University College London LondonWC1H 0AH United Kingdom

In this study, AlSiMgMnCu alloys with different Cu and Mg contents were fabricated by high vacuum die casting (HVDC) technique. The phase formation and their microstructure evolution are quantitatively studied by serial block-face scanning electron microscopy (SBFSEM) at nano-scale in three-dimensions (3D). Through analyzing their 3D microstructure, effects of the spatial distribution, volume fractions and morphology of the intermetallic phases on the alloy’s mechanical properties are comprehensively discussed. It is found that, with higher Cu content and lower Mg content, the nucleation and growth of θ-Al2Cu phase would have advantage over Q-Al5Cu2Mg8Si6 phase. In contrast, decreasing Cu/Mg ratio by increasing Mg content is in favor of the nucleation and growth of the Q-Al5Cu2Mg8Si6 phase. The uniformly distributed fine θ-Al2Cu phase provides the highest contribution to the strengthening of the HVDC AlSiMgMnCu alloys. For the Cu/Mg ratio to be 3, an as-cast HVDC Al-10Si-0.2Mg-0.5Mn-0.6Cu alloy with optimized ultimate tensile strength, yield strength and elongation of 330 MPa, 162 MPa and 10.2%, respectively, had been produced. © 2022, The Authors. All rights reserved.

关键词： Scanning electron microscopy

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Exploring the mechanisms of texture evolution in a low-alloyed Mg-Zn-Ca alloy during extrusion

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materials Characterization 2025年 225卷

作者： Wang, Hua Dong, Jialiang Fu, Penghuai Qiu, Cheng Zhang, Datong Peng, Liming Chen, Daolun National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University Shanghai200240 China National Engineering Research Center of Near-net-shape Forming for Metallic Materials South China University of Technology Guangzhou510640 China Department of Mechanical Industrial and Mechatronics Engineering Toronto Metropolitan University TorontoONM5B 2K3 Canada School of Materials Science and Engineering Guizhou Minzu University Guiyang550025 China

A non-basal texture component was observed in an extruded Mg-1.2Zn-0.1Ca alloy. The microstructural evolution during extrusion was examined via electron backscatter diffraction (EBSD) in detail to identify the mechanisms for the formation of non-basal texture components. Continuous dynamic recrystallization (CDRX) was the predominant mechanism to refine the coarse parent grains. Both the recrystallized and un-recrystallized grains gradually transferred from non-basal texture component into basal texture with 〈01−10〉 parallel to the extrusion direction with increasing strain. Besides, a non-basal texture component 〈20−21〉 − occurred in the recrystallized grains at the final stage of extrusion, and it was fully achieved in the extruded bar. CDRX mechanism was not the direct reason for the formation of − texture. Further analysis demonstrated that the activation of dislocation slip and preferential grain growth were the primary contributing factors. © 2025 Elsevier Inc.

关键词： Dynamic recrystallization

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On the formation mechanism of Cr nitrides in an additively manufactured duplex stainless steel

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materials Characterization 2025年 227卷

作者： Guo, Junyao Dong, Haokai Liao, Wenzheng Guo, Wei Zhang, Jiantao Chang, Keke State Key Laboratory of Advanced Marine Materials Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo 315201 China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 China National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials South China University of Technology Guangzhou 510640 China Guangzhou City University of Technology Guangzhou 510800 China

Cr nitrides are usually considered as a detrimental phase to corrosion resistance and mechanical properties of duplex stainless steels (DSSs), while their formation mechanism in non-equilibrium conditions is not yet fully understood. This study revisits the precipitation behaviors of Cr nitrides in a 2205 DSS fabricated via selective laser melting (SLM). It reveals that the nanoscale enrichments of Cr and N at both the grain boundaries (GBs) and the surface of intragranular nano-inclusions are CrN of B1 structure, while the Cr2N (hexagonal structure) forms mainly at the GBs. Direct experimental evidence for topological transformation from CrN to Cr2N is provided. The competitive precipitation behavior of nitrides from the supersaturated ferrite is quantitatively addressed by thermodynamic and first-principles calculations. Impressively, the much lower strain energy shared on both sizes of ferrite and particle is the main cause for the priority precipitation of CrN, albeit Cr2N is thermodynamically more stable. The present study provides both experimental and theoretical basis for the precursor role of CrN in Cr2N precipitation.

关键词： Cr nitrides Duplex stainless steel First-principles calculations Non-equilibrium precipitation Strain energy

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Hydraulic control system of mechanical energy stored type powder high velocity compaction machine 2

Hydraulic control system of mechanical energy stored type po...

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2019 2nd International Conference on Aeronautical, Aerospace and Mechanical Engineering, AAME 2019

作者： You, Dongdong Zhu, Qian Zhu, Yanghui Li, Fenglei National Engineering Research Center of Near-net-shape Forming for Metallic Materials South China University of Technology Guangzhou510640 China Metastable Materials Science and Technology State Key Laboratory Yanshan University Qinhuangdao066004 China

An automatic control scheme of spring energy storage by hydraulic control of spring compression is presented and implemented in this paper to improve the automation level, control accuracy and production efficiency of the existing HVC machine with mechanical energy storage type. The hydraulic system, servo system, and PLC codes are developed. The PID control optimization is applied for the control error accuracy of the machine. The transfer function is derived, and the genetic algorithm is used to optimize the PID parameters. The control scheme is implemented in the updated machine. The experimental results of iron powder HVC are in agreement with the predicted and calculated values. The reliability and validity of the automatic control scheme is verified. The research facilitates the industrial application of this kind of equipment. © 2019 IOP Publishing Ltd. All rights reserved.

关键词： Genetic algorithms

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Influence of Intermetallics and Solute Solution on the Performance of the Heat Treated Hvdc Alsimgmncu Alloys at Nano-Scale

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SSRN 2022年

作者： Liu, Fei Qin, Jun Zhao, Haidong Jiang, Yuanhang Zheng, Huiting Chen, Bo National Engineering Research Center of Near-net Shape Forming for Metallic Materials South China University of Technology Guangzhou510641 China Key Laboratory of Advanced Civil Engineering Materials Ministry of Education School of Materials Science and Engineering Tongji University Shanghai201804 China Department of Gastrointestinal Surgery Renji Hospital School of Medicine Shanghai Jiao Tong University Shanghai200127 China London Centre for Nanotechnology University College London LondonWC1H 0AH United Kingdom

A method to calculate solute solution in Al alloy castings, based on the serial block-face scanning electron microscopy (SBFSEM) measurement at nano-scale, was proposed. For the high vacuum die casting (HVDC) Al-10Si-0.4MgMn-0.6Cu alloy, it reveals that the solute fractions of the Si, Mg and Cu in the Al matrix reaches about 0.39 wt.%, 0.15 wt.%, and 0.10 wt.%, respectively, under the as-cast condition. After it was heat treated via T5 process, larger nano-scale precipitation phases with low density and non-uniform distribution were formed in the α-Al matrix. After T6-treated, the narrow neck regions of the seaweed-like α-Fe phase particles were fragmented as well, but could not dissolve into the α-Al matrix. The solute fractions of the Si, Mg and Cu in the α-Al matrix increases to 0.75 wt.%, 0.23 wt.%, and 0.43 wt.%, respectively. Hence, finer nano-scale precipitation phases with high density and uniform distribution are formed in the Al matrix. Consequently, the ultimate tensile strength, yield strength and elongation of the T6-treated alloy simultaneously increase of about 15%, 52% and 63%, respectively. It presents that the solute solution during high pressure die casting solidification has decisive effect on the mechanical properties before and after heat treatment. © 2022, The Authors. All rights reserved.

关键词： Scanning electron microscopy

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Solute-homogenization model and its experimental verification in Mg-Gd-based alloys

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Journal of materials Science & technology 2018年第7期34卷 1132-1141页

作者： Shengnan Qian Chuang Dong Tianyu Liu Ying Qin Qing Wang Yujuan Wu Lidong Gu Jianxin Zou Xiangwen Heng Liming Peng Xiaoqin Zeng Key Laboratory of Materials Modification (Ministry of Education) School of Material Science and Engineering Dalian University of Technology National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composite Shanghai Jiao Tong University

Composition homogenization in solid solution is important for industrial alloys. In the present work, a solute homogenization model is proposed based on the chemical short-range-order tendency in Mg-Gd- based alloys. After a calculation using the cluster-plus-glue-atom model, the stable Mg-Gd structural unit is derived, [Gd-Mg12 ]Mg6, where one solute Gd is nearest-neighbored with twelve Mg atoms to form the characteristic hcp cluster [Gd-Mg12 ] and this cluster is matched with six Mg glue atoms. Such a local unit is then mixed with [Mg-Mg12 ]Mg3, the stable unit for pure Mg. Assuming that the Gd-containing units are arranged in fcc- or bcc-like lattice points and the Mg units in their octahedral interstices, three proportions between the two units are obtained, 1：1, 2：3, and 1：3, which constitute three solute homogenization modes. The prevailing Mg-Gd-based alloys are consequently classified into three groups, respectively exemplified by GW103 K （Mg-10Gd-3Y-0.4Zr, wt%）, GW83 K （Mg-SGd-3Y-0.4Zr）, and GW63 K （Mg-6Gd- 3Y-0.4Zr）. Mg-Gd-Y-Zr alloys were designed following the model （where Y and Zr were also added in substitution for Gd） and prepared by permanent-mould casting. According to their mechanical properties, the 1：3 alloy （Mg-5.9Gd-1.6Y-0.4Zr） shows the best comprehensive properties （ultimate tensile strength 305 MPa, yield strength 186 MPa, elongation 9.0%） in solution plus ageing state.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of materials Science ＆ technology.

关键词： Mg-Gd solid solution Cluster-plus-glue-atom model Solute-homogenization model Mg-Gd-Y-Zr cast alloys

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Synthesis and Properties of Poly (DL-lactide)/Poly (Ethylene Glycol) Diblock Copolymer

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IOP Conference Series: Earth and Environmental Science 2021年第5期781卷

作者： Xiaoqi Chen Jia Tian Lu Bai Haijun Zhou Mengmeng Zhou Jijun Xiao Yantao Li Institute of Energy Source Hebei Academy of Sciences Shijiazhuang China School of Materials Science and Engineering Hebei University of Science and Technology Hebei Engineering Laboratory of Aviation Lightweight Composite Materials and Processing Technology Hebei Key Laboratory of Material Near-Net Forming Technology Hebei Key Laboratory of Flexible Functional Materials Shijiazhuang 050018 China

Poly (DL-lactide)/Poly (Ethylene Glycol) Diblock Copolymer is successfully synthesized with mPEG and DL-LA as main raw materials. FT-IR, 1H-NMR and DSC are used to study the influence of precipitant species and dosage on the properties of copolymer; and the effects of the m (mPEG)/m(LA)'s ratio on the copolymer's molecular weight (Mn), glass transition temperature (Tg) and the properties of residual monomers. The results showed that the precipitant was ether, dichloromethane / ether was 1/6, m (m PEG)/m (LA) was 2/1.8, the synthesized Poly (DL-lactide)/Poly (Ethylene Glycol) Diblock Copolymers, the residual monomer was only 0.26 and the solvent residue was only 0.04.

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Microstructure and mechanical properties of as-cast Mg-8Li-xZn-yGd(x=1,2,3,4;y=1,2) alloys

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Transactions of Nonferrous Metals Society of China 2019年第6期29卷 1211-1222页

作者： Si-jie OUYANG Wen-cai LIU Guo-hua WU Hao JI Zhan-kui GAO Xiang PENG Zhong-quan LI Wen-jiang DING National Engineering Research Center of Light Alloy Net Forming and Key State Laboratory of Metal Matrix Composite School of Materials Science and EngineeringShanghai Jiao Tong University Shanghai 200240 China Shanghai Innovation Institute for Materials Shanghai 200444 China Shanghai Spaceflight Precision Machinery Institute Shanghai 201600 China Shanghai Engineering Technology Research Center of Near-Net-Shape Forming for Metallic Materials Shanghai 201600 China

The as-cast Mg-8 Li-xZn-yGd(x=1 2, 3,4;y=1,2;wt.%)alloys were prepared in a vacuum induction furnace and their microstructure and mechanical properties were investigated. The results show that the increase of Zn content results in the volume fraction of W-phase(Mg3 Zn3 Gd2) increasing while that of Mg3 Gd phase decreasing. The strength of Mg-8 Li-xZn-1 Gd alloys is improved with the increase of Zn content,which is ascribed to the second phase strengthening of fine strip-like W-phase and the solid solution strengthening of Zn *** Mg-8 Li-4 Zn-yGd alloys,the increase of Gd content leads to the appearance of coarse and discontinuous net-like W-phase, which decreases the strength. The Mg-8 Li-4 Zn-1 Gd alloy exhibits an optimum comprehensive performance with the yield strength, ultimate tensile strength and elongation of 154.7 MPa, 197.0 MPa and 12.4%, respectively. In addition,the aging behavior of the typical alloys was also investigated.

关键词： Mg-Li-Zn-Gd alloy W-phase microstructure mechanical properties aging behavior

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Density Functional Theory Simulation of PVDF Transition in Electric Field Polarization

Density Functional Theory Simulation of PVDF Transition in E...

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International Conference on Mathematics, Modeling and Simulation Technologies and Applications

作者： Yan Li Xu Ma Yanhong Ding Xudong Li Zisheng Li School of Material Science and Engineering Tianjin University of Technology Tianjin Engineering Center of Near-Net-Shape Forming Technology for Metallic Materials School of Electrical and Electrical and Electronic Engineering Tianjin Key Laboratory of Film Electronic and Communication DevicesTianjin University of Technology

ISBN: (纸本)9781713800361

The molecular model of PVDF is established by the calculation method of density functional theory(DFT).A process of applying an electric field of different magnitude to PVDF to cause a phase transition was *** transformation of the molecular chain of PVDF molecules under the electric field strength below 0.05 Ha was studied in *** is found that the main role in the transformation process is the transformation of the carbon *** we calculated the dipole moment and average molecular polarizability of the PVDF molecular chain under different *** results showed the dipole moment increases from 7.6 Debye to 9.9 Debye with the structure of α PVDF to β PVDF,the mean polarizability also increased from 39.5 to *** calculations provide theoretical calculations for the study of PVDF and demonstrate the effect of electric field polarization on the production of β PVDF.

关键词： DFT PVDF Polarization polyvinylidene fluoride Polarization discrete Fourier transform dipole moments Electric fields computational methods molecular model

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Effect of refining processes on inclusions and mechanical properties of cast Al-2Li-2Cu-0.2Zr alloy

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Transactions of Nonferrous Metals Society of China 2019年第7期29卷 1375-1382页

作者： Mian RONG Liang ZHANG Guo-hua WU Wei-wei LI Xiao-long ZHANG Jiang-wei SUN Wen-jiang DING National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China Mag (Kunshan) New Material Technology Co. Ltd.Kunshan 215300China

The effect of different refining processes on inclusions and mechanical properties of cast Al-2Li-2Cu-0.2Zr alloy was investigated, including two-stage hexachloroethane (C2Cl6) refining process, two-stage rotating gas bubbling refining process and two-stage composite refining process. It was found that the two-stage composite refining process, which combined C2Cl6 and rotating gas bubbling, can significantly improve the melt purity and mechanical properties of cast Al-2Li-2Cu-0.2Zr alloy. Compared to the unrefined alloy, the volume fraction of gas porosity defects and slag inclusions decreased from 1.47% to 0.12%, and the yield strength, ultimate tensile strength and elongation of as-quenched alloy increased from 113 MPa,179 MPa and 3.9% to 142 MPa, 293 MPa and 18.1%, respectively. C2Cl6 was first utilized to degas and remove large size slag inclusions before lithium addition, and then the rotating gas bubbling was utilized to do the further degassing and remove the suspended fine inclusions after lithium addition. The two-stage composite refining process can take advantage of two methods and get the remarkable refining effect.

关键词： Al-Li-Cu-Zr alloy refining process microstructure melt purity mechanical properties

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