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Isochronal and isothermal phase transformation in β + αacicular Ti-55531

JOURNAL OF MATERIALS SCIENCE 2020年第7期55卷 3073-3091页

作者： chen, fuwen Xu, Guanglong Zhou, Kechao Chang, Hui Cui, Yuwen Nanjing Tech Univ Tech Inst Adv Mat Nanjing 210009 Jiangsu Peoples R China Nanjing Tech Univ Coll Mat Sci & Engn Nanjing 210009 Jiangsu Peoples R China Cent S Univ State Key Lab Powder Met Changsha 410083 Hunan Peoples R China

Duplex aging is one of the common heat treatments in titanium alloys. The microstructure introduced in the first-step aging has an effect on the growth/dissolution of alpha in the second-step aging. In the present work, a beta + alpha(acicular) microstructure is preset in Ti-55531 (Ti-5Al-5Mo-5V-3Cr-1Zr wt%) alloy. The isochronal and isothermal phase transformation kinetics in the second-step aging is studied by combining the dilatometer test with microstructure characterization and local composition mapping. The phase transformations and corresponding temperature ranges are determined as beta -> alpha(acicular) [643-845 K] and alpha(acicular) -> beta [845-1130 K] by isochronal annealing. A TTT diagram for isothermal transformation kinetics is plotted based on the transformed phase fraction and reproduced by Johnson-Mehl-Avrami theory. The calculated kinetic curves are in good agreement with experiment ones. The C-shaped TTT curves verify the classical nucleation and growth of alpha in the second-step aging. In comparison with Ti-55531 alloy with preset beta + alpha(lath) microstructure (in authors' previous work), the alpha precipitation exhibits prolonged incubation period and slowed average transformation rate, which is evidenced by a right shift of C-curves for the alpha precipitation portion along the time axis. However, the C-curves of alpha dissolution show a left shift on the TTT diagram. The precipitation kinetics of alpha aciculae from dilatometry is synchronous with that obtained from the diffusion of Al detected in STEM mapping, while the diffusion of slow-diffusion elements lags behind the structural transformation. The TTT diagram and the dataset of microstructure features obtained in the present work can be employed to optimize processing in duplex aging.

关键词： Microstructure

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Phase equilibria and microstructure development in Mg-rich Mg-Gd-Sr alloys: Experiments and CALPHAD assessment

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CALPHAD-COMPUTER COUPLING OF PHASE DIAGRAMS AND THERMOCHEMISTRY 2023年第1期82卷

作者： Long, Qiang Meng, Na chen, fuwen Zhang, Ligang Tao, Xiaoma Liu, Libin Xu, Guanglong Cui, Yuwen Nanjing Tech Univ Coll Mat Sci & Engn Nanjing 211816 Peoples R China Cent South Univ Sch Mat Sci & Engn Changsha 410083 Peoples R China Guangxi Univ State Key Lab Featured Met Mat & Life cycle Safety Nanning 530004 Peoples R China

Mg-Sr alloys are promising to fabricate orthopedic implants. The alloying of rare earth elements such as Gd may improve the comprehensive mechanical properties of Mg-Sr alloys. The information on the phase diagram and the microstructure development are required to design chemical composition and microstructure of Gd alloyed Mg-Sr alloys. The phase equilibria and the microstructure development in Mg-rich Mg-Gd-Sr alloys (Gd, Sr < 30 at. %) are experimentally investigated via phase identification, chemical analysis, and microstructure observation with respect to the annealed ternary alloys. The onset temperatures of liquid formation are measured by differential scanning calorimetry. A thermodynamic database of the Mg-rich Mg-Gd-Sr ternary system is developed for the first time via CALPHAD (CALculation of PHAse Diagram) approach assisted by First-Principles calculations. The thermodynamic calculations with the developed database enable a well reproduction of the experimental findings and the physical-metallurgical understanding of the microstructure formation in solidification and annealing.

关键词： Mg -Gd -Sr Phase equilibria CALPHAD Thermodynamic assessment First-principles calculations

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Improved fracture toughness by microalloying of Fe in Ti-6Al-4V

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MATERIALS & DESIGN 2020年 185卷

作者： chen, fuwen Gu, Yulei Xu, Guanglong Cui, Yuwen Chang, Hui Zhou, Lian Nanjing Tech Univ Tech Inst Adv Mat Nanjing 210009 Jiangsu Peoples R China Nanjing Tech Univ Coll Mat Sci & Engn Nanjing 210009 Jiangsu Peoples R China ICMA Zaragoza 50009 Spain

The widely used Ti-6Al-4V (TC4) titanium alloy has been modified through the micro-alloying of Fe. The microstructural features and mechanical properties of the designed alloy, TC4F, are compared with other alloys in Ti-6Al-4V class by combining experimental characterizations and thermodynamic calculations. TC4F alloy not only maintains strength, hardness, and elongation similar to baseline TC4 but also exhibits improved fracture toughness comparable to TC4_ELI and even superior to TC4_DT under the heat-treated condition. It opens up a new cost-reducing way to enhance fracture toughness in place of controlling interstitial contents, showing potential in engineering applications. The discerned mechanisms indicate that the trace addition of Fe gives rise to composition redistribution between V and Fe in the beta phase, boosts the lattice distortion and vibration, thereafter enhances Young's modulus and fracture toughness. It has been validated and verified by experiments, thermodynamic calculations, and Hahn-Rosenfield empirical research. The enhanced fracture toughness also benefits from the kinked beta+alpha lamellar microstructure at crack tip as well as the improved fracture surface due to the Fe addition. The enlarged plastic zone, redirected crack propagation, and more dimples with even-distributed size additionally contribute to the improvement of fracture toughness. (C) 2019 The Authors. Published by Elsevier Ltd.

关键词： Micro-alloying of Fe Ti-6Al-4V Fracture toughness Enhanced modulus Composition redistribution of V and Fe

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粉煤灰和烧成温度对矾土基轻量莫来石材料结构及性能的影响

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硅酸盐通报 2023年第4期42卷 1488-1495页

作者：陈富文桑绍柏万卓夫马宇洲廖宁武汉科技大学省部共建耐火材料与冶金国家重点实验室武汉430081 高温材料与炉衬技术国家地方联合工程研究中心武汉430081

耐火材料的轻量化是高温工业节能的重要方向。以三级生矾土和粉煤灰为主要原料,采用原位分解法制备轻量M60莫来石材料,研究在不同烧成温度下粉煤灰对轻量M60莫来石材料结构与性能的影响。结果表明:在1400、1500℃烧成温度下,粉煤灰的引... 详细信息

耐火材料的轻量化是高温工业节能的重要方向。以三级生矾土和粉煤灰为主要原料,采用原位分解法制备轻量M60莫来石材料,研究在不同烧成温度下粉煤灰对轻量M60莫来石材料结构与性能的影响。结果表明:在1400、1500℃烧成温度下,粉煤灰的引入使材料的体积密度降低,总气孔率增加,耐压强度大幅提升;引入粉煤灰的试样1500℃烧成后导热系数有明显下降。当烧成温度达到1600℃时,粉煤灰的引入使材料的总气孔率减小,体积密度略有增加,导热系数明显增加。此外,粉煤灰的引入会降低材料的荷重软化温度。引入34.0%(质量分数)粉煤灰后,所制备莫来石材料的体积密度降低了8%~13%,总气孔率增加了23%~37%;经1500℃烧成后,材料耐压强度达到(122.6±2.2)MPa,1000℃测试时的导热系数仅为0.616 W/(m·K)。

关键词：三级生矾土莫来石轻量化粉煤灰烧成温度导热系数强度

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Experimental investigation and thermodynamic description of Mg-Sc-Zn ternary system

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CALPHAD-COMPUTER COUPLING OF PHASE DIAGRAMS AND THERMOCHEMISTRY 2022年第0期77卷 102406-102406页

作者： Wang, Yiheng Gao, Kang Tao, Xiaoma Ko, Won-Seok Wang, Jiang chen, fuwen Xu, Guanglong Cui, Yuwen Nanjing Tech Univ Coll Mat Sci & Engn Nanjing 211816 Peoples R China Guangxi Univ MOE Key Lab New Proc Technol Nonferrous Met & Mat Guangxi Key Lab Proc Nonferrous Met & Featured Mat Nanning 530004 Peoples R China Univ Ulsan Sch Mat Sci & Engn Ulsan 44610 South Korea Guilin Univ Elect Technol Guangxi Key Lab Informat Mat Guilin 541004 Peoples R China

The determination of the Mg-Sc-Zn phase diagram was motivated by the demand for alloying Mg-Sc shape memory alloy with Zn to enhance the phase stability of B2-structured phase at elevated temperatures. In the present work, the phase equilibria at 773 K and 873 K were experimentally investigated by analyzing chemical compositions and crystal structures of individual phases in the annealed alloy samples. MgSc_B2 and ScZn_B2 failed to form a continuous solid solution from the Mg-Sc binary boundary to the Sc-Zn binary boundary. Mg atoms were found to dissolve into the ScZn_B2 lattice that substitute Zn with a solid solubility up to 5 at.%. MgSc_B2 was proven not thermodynamically stable above 773 K. The solid solubility of Zn in bcc_A2 was measured to be around 1 at.%, giving rise to a narrow homogeneous range alongside the Mg-Sc binary vicinity. A thermodynamic database of Mg-Sc-Zn system was then successfully developed by optimizing parameters to reproduce phase present, phase equilibria, solidification paths, and transformation temperatures, etc. The assessed database together with the experimental findings can be utilized in the compositional design of multicomponent alloying in Mg-Sc based shape memory alloys.

关键词： Mg-Sc-Zn Phase equilibria CALPHAD Thermodynamic modeling Solidification

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Hierarchical eutectic structure and superior mechanical property in low cobalt content AlCo0.2CrFeNi2.1 alloy by laser metal deposition

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JOURNAL OF ALLOYS AND COMPOUNDS 2022年 915卷 1页

作者： Feng, Chong Chai, Xiaoyu Sun, Zhonggang Liu, Xiaochun Wang, Jiang Tao, Xiaoma chen, fuwen Xu, Guanglong Cui, Yuwen Nanjing Tech Univ Coll Mat Sci & Engn Nanjing 211816 Peoples R China Changsha Univ Sci & Technol Inst Met Changsha 410114 Peoples R China Guilin Univ Elect Technol Guangxi Key Lab Informat Mat Guilin 541004 Peoples R China Guangxi Univ Key Lab New Proc Technol Nonferrous Met & Mat Guangxi Key Lab Proc Nonferrous Met & Featured Mat MOE Nanning 530004 Peoples R China Cent South Univ Sch Mat Sci & Engn Changsha 410083 Peoples R China

The fabrication of AlCo0.2CrFeNi2.1 high entropy alloy via laser metal deposition (LMD) was motivated and implemented by the demand for overcoming the strength-ductility trade-off of the as-cast alloys due to the Co concentration. The microstructure features of AlCo0.2CrFeNi2.1 alloy were characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and electron back-scattered diffraction. The mechanical properties were evaluated by a tensile test at room temperature. The synergy of reduced Co content and LMD process led to the formation of hierarchical eutectic microstructures consisting of columnar grains, eutectic colonies, alternately arranged fcc(L12)+B2 lamellae, and coherent Cr-rich nanoprecipitates in B2. The growth direction of those eutectic structures was found to be mainly parallel to the building direction (BD). The fcc(L12)/B2 eutectics agreed well with the Kurdjumov-Sachs orientation relationship of [110}B2//[111}L12, and < 111 > B2// < 110 > L12. The LMD fabricated AlCo0.2CrFeNi2.1 exhibited anisotropic mechanical properties when stretched in BD and transverse direction (TD). An excellent combination of the ultimate tensile strength (1246 MPa) and ductility (17.1%) was achieved in the BD, better than the as-cast counterpart. The elevated mechanical properties could be attributed to the high cooling rate solidification induced microstructural refinement. The same interlamellar spacing in BD and TD embraced a nearly equal ability to block dislocation movement and gave rise to the similar yield tensile strength. The differences in grain/colony size induced boundary strengthening in BD and TD were evaluated to account for the remarkable changes in ultimate tensile strength as well as ductility. (c) 2022 Elsevier B.V. All rights reserved.

关键词： Laser metal deposition (LMD) AlCo 0 2 CrFeNi 2 1 Microstructure features Tensile property Strengthening

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经导管取栓联合置管溶栓治疗下肢深静脉血栓的临床疗效

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血管与腔内血管外科杂志 2024年第3期10卷 353-356,366页

作者：陈明朗江谋应金涛严雄陈付文丁清安庆市第一人民医院介入与血管外科安徽安庆246400

目的探讨经导管取栓联合置管溶栓治疗下肢深静脉血栓形成(LDVT)的临床疗效。方法收集2019年3月至2023年2月安庆市第一人民医院收治的76例LDVT患者的临床资料,按照治疗方法的不同将其分为药物组(n=38,采用保守药物治疗)与介入组(n=38,... 详细信息

目的探讨经导管取栓联合置管溶栓治疗下肢深静脉血栓形成(LDVT)的临床疗效。方法收集2019年3月至2023年2月安庆市第一人民医院收治的76例LDVT患者的临床资料,按照治疗方法的不同将其分为药物组(n=38,采用保守药物治疗)与介入组(n=38,采用经导管取栓联合置管溶栓治疗)。比较两组患者临床指标,治疗前、治疗后7d健患侧大腿围差值、小腿围差值及凝血功能指标,评估临床疗效与血栓清除效果,统计两组患者治疗后并发症发生情况。结果介入组患者治疗时间、症状改善时间、住院时间均短于药物组患者,差异均有统计意义(P﹤0.05)。治疗后,两组患者健患侧大腿围差值、小腿围差值均小于本组治疗前,且介入组患者均小于药物组患者,差异均有统计学意义(P﹤0.05)。治疗后,两组患者凝血酶原时间(PT)、活化部分凝血活酶时间(APTT)均较本组治疗前延长,纤维蛋白原(FIB)、D-二聚体(D-D)水平均较本组治疗前下降,且介入组患者PT、APTT均长于药物组患者,FIB、D-D水平均低于药物组患者,差异均有统计学意义(P﹤0.05)。介入组患者血栓清除效果、临床疗效均优于药物组患者,差异均有统计学意义(P﹤0.05)。两组患者治疗后并发症发生率比较,差异无统计学意义(P﹥0.05)。结论经导管取栓联合置管溶栓治疗LDVT可获得更为理想的临床疗效与血清清除效果,并可缩短溶栓时间,提高治疗安全性。

关键词：下肢深静脉血栓形成经导管取栓置管溶栓

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轧钢加热炉内传热过程的数值模拟及节能分析

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工业炉 2024年第3期46卷 1-6页

作者：孙义燃桑绍柏陈富文王光阳李亚伟武汉科技大学省部共建耐火材料与冶金国家重点实验室武汉科技大学高温材料与炉衬技术国家地方联合工程研究中心

建立了钢坯在天然气轧钢加热炉内加热过程的传热模型，分析了钢坯加热情况、天然气消耗量和炉墙散热情况，量化研究了降低炉衬综合导热系数和涂覆红外辐射涂层的节能效果。结果表明，随着炉衬综合导热系数的降低和红外辐射涂层发射率的... 详细信息

建立了钢坯在天然气轧钢加热炉内加热过程的传热模型，分析了钢坯加热情况、天然气消耗量和炉墙散热情况，量化研究了降低炉衬综合导热系数和涂覆红外辐射涂层的节能效果。结果表明，随着炉衬综合导热系数的降低和红外辐射涂层发射率的增加，钢坯升温时间缩短，天然气消耗量减少；将炉衬综合导热系数从0.8 W/（m·K）降至0.4 W/（m·K）、炉膛内壁发射率从0.5增至0.8时，钢坯加热至1 460 K的时间缩短了19.7%，天然气消耗量减少了13.6%。分析认为，在选择低导热系数的轻量化工作层的同时增加近中红外波段高发射率红外辐射涂层是更值得推荐的加热炉节能方式。

关键词：轧钢加热炉节能导热系数红外辐射涂层非稳态数值仿真

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Adaptive graph transformer with future interaction modeling for multi-agent trajectory prediction

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KNOWLEDGE-BASED SYSTEMS 2025年 316卷

作者： chen, Xiaobo Wang, Junyu Deng, fuwen Li, Zuoyong Shandong Technol & Business Univ Sch Comp Sci & Technol Yantai 264005 Peoples R China Minjiang Univ Sch Comp & Big Data Fuzhou 350121 Peoples R China

Forecasting the trajectories of traffic agents is essential for autonomous systems such as self-driving cars and social robots to guarantee safety in crowded scenarios. Capturing social interactions between agents and generating informative future features bring great challenges to accurate trajectory prediction. To this end, this paper proposes a novel multi-agent trajectory prediction model called AGTFI based on the adaptive graph transformer and future interaction modeling. First, an adaptive graph transformer (AGT) proficient at extracting node and edge features is introduced to capture the complex social interactions between traffic agents. Moreover, a two-stage prediction approach is devised where the first stage is devoted to generating pre-estimated future motion features by bidirectional corrected GRU (BCGRU) and the second stage further incorporates future social interactions into BCGRU to reduce prediction errors. Quantitative and qualitative evaluations of AGTFI on benchmark datasets, including ETH-UCY, SDD, and INTERACTION demonstrate the effectiveness of our model. Ablation studies are conducted to verify the rationale behind the model components.

关键词： Trajectory prediction Graph transformer Attention mechanism Bidirectional decoding

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A novel optimized asynchronous federated learning framework

arXiv

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arXiv 2021年

作者： Zhou, Zhicheng chen, Hailong Li, Kunhua Hu, Fei Yan, Bingjie cheng, Jieren Wei, Xuyan Liu, Bernie Li, Xiulai chen, fuwen Sui, Yongji School of Computer Science and Technology Hainan University Haikou China Hainan University Haikou China RobAI-Lab Hainan University Hainan Blockchain Technology Engineering Research Center Haikou China

Federated Learning (FL) since proposed has been applied in many fields, such as credit assessment, medical, etc. Because of the difference in the network or computing resource, the clients may not update their gradients at the same time that may take a lot of time to wait or idle. That’s why Asynchronous Federated Learning (AFL) method is needed. The main bottleneck in AFL is communication. How to find a balance between the model performance and the communication cost is a challenge in AFL. This paper proposed a novel AFL framework VAFL. And we verified the performance of the algorithm through sufficient experiments. The experiments show that VAFL can reduce the communication times about 51.02% with 48.23% average communication compression rate and allow the model to be converged faster. The code is available at https://***/RobAI-Lab/VAFL Copyright © 2021, The Authors. All rights reserved.

关键词： Edge computing

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