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Microstructure, Mechanical and Soft Magnetic Properties of In-Situ Tic Reinforced Fe27.5ni27.5co45-Based Medium Entropy Composites

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SSRN 2023年

作者： Chen, Tao Jiang, Zhenfei Fu, Zhiqiang Chu, Chenliang Chen, Weiping Guangdong Key Laboratory for Advanced Metallic Materials Processing South China University of Technology Guangdong Guangzhou510641 China National Engineering Research Center of Near-net-shape Forming for Metallic Materials South China University of Technology Guangzhou510641 China

The insufficient mechanical properties of conventional soft magnetic materials (SMMs) hinder their widespread applications, and unfortunately, traditional strengthening mechanisms could dramatically deteriorate their soft magnetic properties without adjusting the alloy composition. Here, we developed TiC/Fe27.5Ni27.5Co45 medium-entropy composites (MECs) possessing multi-scale microstructure consisting of ultrafine and micron-sized grains by introducing in-situ formed TiC nano particles during the spark plasma sintering (SPS) process. Compared with the precipitate-free Fe27.5Ni27.5Co45 medium-entropy alloy, TiC/Fe27.5Ni27.5Co45 MEC with ~8.7 vol% TiC (noted as Ti5-MEC) demonstrated a significant improvement in compressive yield strength (from 459 MPa to 1114 MPa), attributing to the grain-boundary strengthening and dispersive precipitation strengthening, as well as hetero-deformation induced (HDI) strengthening. Meanwhile, the Ti5-MEC exhibits a high saturation magnetization (Ms) of 153.1 emu/g and a low coercivity (Hc) of ~8.2 Oe, indicating excellent soft magnetic properties, primarily due to the multi-scale microstructure. Our work has demonstrated that engineering multi-scale microstructures in MECs is an effective strategy to achieve desirable combinations of soft magnetic and mechanical properties. © 2023, The Authors. All rights reserved.

关键词： Titanium carbide

Strengthening Mechanisms and Deformation Behavior of a Non-Equiatomic Ni35Co27.5Cr27.5Al5Ti5 High-Entropy Alloy with Spherical L12 Nanoprecipitates

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SSRN 2023年

作者： Huang, Liran Fu, Zhiqiang Chu, Chenliang Chen, Weiping Wang, Hao Zhu, Dezhi Guangdong Key Laboratory for Advanced Metallic Materials Processing South China University of Technology Guangdong Guangzhou510641 China National Engineering Research Center of Near-net-shape Forming for Metallic Materials South China University of Technology Guangzhou510641 China

Introducing L12 precipitates into face-centered-cubic (FCC) structured equiatomic CoCrNi medium-entropy alloy (MEA) is an effective means to improve its disappointing strength (2 precipitates are usually obtained by complicated thermomechanical processing (TMP), accompanying the presence of cellular L12 precipitates at the grain boundaries (GBs) which are detrimental to the mechanical properties. In this work, we designed and fabricated a non-equiatomic Ni35Co27.5Cr27.5Al5Ti5 HEA consisting of sole spherical L12 nanoprecipitates without any other phases via a simplified short-term heat treatment processing, i.e., casting followed by homogenization and aging. The as-cast, homogenized and aged HEA all possess equiaxed grains, in the meantime, the as-cast HEA exhibits equiaxed dendritic microstructure. In the as-cast and aged HEA, spherical L12 nanoprecipitates are uniformly distributed in the FCC matrix, and the L12 nanoprecipitates of the aged HEA have smaller size and higher volume fraction in comparison with those of the as-cast HEA. The aged Ni35Co27.5Cr27.5Al5Ti5 HEA has the best mechanical properties among the three states, exhibiting a tensile yield strength of ~916 MPa, an ultimate tensile strength of ~1220 MPa, and a total elongation of ~21.5%. Precipitation strengthening is primarily responsible for the aged HEA. Digital image correlation (DIC) images corresponding to the tensile testing have shown that the homogenized and aged HEA exhibit uniform deformation, whereas the stress concentration could be observed in the as-cast HEA. Additionally, electron channeling contrast imaging (ECCI) analyses reveal that multiple deformation mechanisms including coherent L12 precipitates, the stacking fault (SF) network, the high-density dislocation walls (HDDWs) and dislocation cells, jointly acted as the dislocation obstacles for the aged HEA, contributing to the excellent strain-hardening ability for the outstanding strength-ductility synergy. © 2023, The Authors. All

关键词： Tensile testing

Molecular Dynamics Simulation of Tensile Mechanical Properties of Nickel-Based Superalloy with Temperature and Co

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SSRN 2024年

作者： Dong, Huicong Chen, Yinghao Wu, Dayong Ma, Haikun Wang, Qian Feng, Zhihao You, Baocai Jia, Chonglin 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 Shenyang Engine Design Institute No. 6 Dongta Street Dadong District Shenyang110000 China AECC Bejing Institute of Aeronautical Materials No.8 Hangcai Avenue Huanshancun Haidian District Beijing100000 China

Co, as one of the new key elements in nickel(Ni)-based superalloys, has attracted extensive attention in the material field. However, the mechanism of the effect of Co on the mechanical behavior of Ni-based superalloys is still controversial. The effect of Co addition on the mechanical properties and deformation mechanism of Ni-based superalloy was studied from the perspective of dislocation evolution and microstructure evolution by molecular dynamics simulation. The results show that the addition of 5% Co can decrease the tensile strength, elastic modulus, yield stress and yield strain of the structure, this is because at low temperatures, the 5wt.% structure will produce more layers of lamellar Hcp phase and invade the γ' phase, causing its mechanical properties to decline. In terms of stacking faults, a large number of obvious stacking faults enter the γ' phase at yield strain, which makes the stacking fault zone more complete and accelerates the structural deformation. In addition, at different temperatures, the addition of Co also showed different characteristics, flow stress was enhanced compared with the original structure, but gradually weakened with the increase of temperature, this is the result that the addition of Co at low temperature causes the structure to generate more fixed Stair-rod dislocations. © 2024, The Authors. All rights reserved.

关键词： Stacking faults

Microstructural Evolution and Hot-Compressive Behavior of Waspaloy Forged Bolts: Experimental and Finite Element Simulation

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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

Influence of Fe-rich phases and precipitates on the mechanical behaviour of Al-Cu-Mn-Fe-Sc-Zr alloys studied by synchrotron X-ray and neutron

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Journal of materials Science & technology 2023年第27期158卷 226-241页

作者： Yuliang Zhao Dongfu Song Shengchuan Wu Shunfu Xie Haoliang Wang Mengmeng Wang Weiwen Zhang Zhenzhong Sun Yubin Ke Shanfeng Wang Wanxia Huang Ricardo Fernández Neutron Scattering Technical Engineering Research Centre School of Mechanical EngineeringDongguan University of TechnologyDongguan 523808China Centro Nacional de Investigaciones Metalúrgicas(CENIM) C.S.I.C.Avda.de Gregorio del Amo 8Madrid 28040Spain National Engineering Research Centre of Near-Net-Shape Forming for Metallic Materials South China University of TechnologyGuangzhou 510641China Institute of New Materials Guangdong Academy of ScienceGuangzhou 510650China State Key Laboratory of Traction Power Southwest Jiaotong UniversityChengdu 610031China Spallation Neutron Source Science Center Dongguan 523803China School of Materials Science and Engineering Anhui Polytechnic UniversityWuhu 241000China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100039China

A multiscale methodology using scanning and transmission electron microscope,synchrotron X-ray nano-tomography and micro-tomography,small angle neutron scattering,and in situ synchrotron X-ray diffrac-tion has been used,to reveal the effect of Fe-rich phases and precipitates on the mechanical behaviour of an Al-Cu-Mn-Fe-Sc-Zr ***α-Al grains size is reduced from 185.1μm(0 MPa)and 114.3μm(75 MPa)by applied ***,it has been demonstrated that suitable heat treatments modify the 3D morphology of Fe-rich phases from interconnected to a disaggregated structure that improves the mechanical properties of the *** size and morphology evolution of fine precipitates under differ-ent ageing temperature and time are *** ageing temperature of 160℃,the precipitates change from GP zones toθ’(around 75 nm in length)with ageing time increasing from 1 h to 24 h;the Vick-ers hardness increases from 72.0 HV to *** high ductility of the Sc,Zr modified Al-Cu alloy is related to the complex shape and the loss of interconnectivity of the Fe-rich particles due to the heat *** evolution of the crystal lattice strains inα-Al,andβ-Fe calculated during tensile test us-ing in-situ synchrotron X-ray diffraction corroborates the influence of the microstructure in the ductility of the modified alloy.

关键词： Al alloy Ageing process Mechanical properties In situ synchrotron X-ray Sc/Zr microalloying Fe-rich phase

Microstructure-Property Correlation and Strain Partitioning Behavior in Medium-Carbon Carbide-Free Bainitic Steel

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SSRN 2023年

作者： Su, Ru Zheng, Xiongwei Kang, Jie Wu, Dayong Zhang, Fucheng Yang, Zhinan Ma, H.K. Hebei Key Laboratory of Material Near-net Forming Technology School of Materials Science and Engineering Hebei University of Science and Technology Hebei Shijiazhuang050000 China College of Metallurgy and Energy North China University of Science and Technology Tangshan063210 China National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan University Qinhuangdao066004 China State Key Laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao066004 China

This paper investigates the correlation between the microstructure, properties, and strain partitioning behavior in a medium-carbon carbide-free bainitic steel through a combination of experiments and Representative Volume Element (RVE) simulations. The results reveal that as the austempering temperatures increase from low to intermediate, the optimal balance of properties shifts from strength-toughness to plasticity-toughness. The formation of fine bainitic ferrite (BF) plates and bainite sheaves under low austempering temperature enhances both strength and toughness. Conversely, the wide size and shape distribution of the retained austenite (RA) obtained through intermediate austempering temperature contribute to increased work-hardening capacity, resulting in enhanced plasticity. During the tensile deformation simulation, the main bearing phase of stress is BF. Plastic strain is predominantly generated at the interface of the two phases in the blocky RA and within the phase in the narrow channel of the film-like RA. It is predicted that crack initiation points mostly occur at the strain concentration between BF and RA at the two-phase interface, potentially leading to crack propagation along the strain failure zone. Furthermore, the morphology of RA plays a vital role in determining the strain partitioning behavior while the volume fraction of the ductile RA plays a crucial role in enhancing impact toughness. © 2023, The Authors. All rights reserved.

关键词： Carbides

Microstructure, Property and Strain Partitioning Dependence of Medium-Carbon Carbide-Free Bainitic Steel

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SSRN 2023年

作者： Su, Ru Zheng, X.W. Kang, Jie Wu, Dayong Ma, Haikun Zhang, F.C. Yang, Zhinan Hebei Key Laboratory of Material Near-net Forming Technology School of Materials Science and Engineering Hebei University of Science and Technology Hebei Shijiazhuang050000 China College of Metallurgy and Energy North China University of Science and Technology Tangshan063210 China National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan University Qinhuangdao066004 China State Key Laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao066004 China

关键词： Carbides

forming Parameter Optimization based on Kriging Model and Genetic Algorithm

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Forming Parameter Optimization based on Kriging Model and Ge...

IEEE Information technology and Mechatronics Engineering Conference (ITOEC)

作者： Junxiong Tang Dongdong You Fenglei Li Yong Cheng National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials Guangdong China Guangdong Key Laboratory for Advanced Metallic Materials Processing Guangdong China Beijing Qingtai Data Technology Co. Ltd. Beijing China

When optimizing the processing parameters for hydraulic forming of sheet metal, improving the process parameters based on actual experiments will increase costs, while finite element simulation will lengthen the design cycle. This study proposes a feasible solution by using a Kriging predictive surrogate model to replace the time-consuming finite element model and combining it with multi-objective genetic algorithm for parameter optimization. The optimal process parameters obtained from the simulation validation of finite element analysis prove the feasibility of this solution. This integrated approach of using machine learning and optimization algorithms is practical and promising for improving efficiency and reducing costs in the manufacturing industry.

关键词：

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