期刊：
Journal of Alloys and Compounds,2025年1020:179457 ISSN：0925-8388
通讯作者：
Wei Li
作者机构：
[Cuiling Deng; Hui Zhou; Zhiqing Zhu; Dapeng Jiang] College of Energy and Power Engineering, Changsha University of Science & Technology, Changsha 410114, China;[Youping Sun] Guangxi Key Laboratory of Automobile Components and Vehicle Technology, Guangxi University of Science and Technology, Liuzhou 545006, China;[Fulin Jiang; Jie Teng; Hui Zhang] College of Materials Science and Engineering, Hunan University, Changsha 410082, China;[Shuang Chen] Hunan Provincial Key Laboratory of Vehicle Power and Transmission System, Hunan Institute of Engineering, Xiangtan 411104, China;[Guowei Bo] College of Energy and Power Engineering, Changsha University of Science & Technology, Changsha 410114, China<&wdkj&>Guangxi Key Laboratory of Automobile Components and Vehicle Technology, Guangxi University of Science and Technology, Liuzhou 545006, China<&wdkj&>College of Materials Science and Engineering, Hunan University, Changsha 410082, China
通讯机构：
[Wei Li] C;College of Energy and Power Engineering, Changsha University of Science & Technology, Changsha 410114, China<&wdkj&>Guangxi Key Laboratory of Automobile Components and Vehicle Technology, Guangxi University of Science and Technology, Liuzhou 545006, China
摘要：
Complex dynamic and static softening behaviors in flow stress evolutions serve as important indicator for optimizing the power or load required by thermomechanical processes of Al-Cu-Mg alloys. However, the flow stress behaviors during the commonly employed industrial multi-stage warm and hot forming of Al-Cu-Mg alloys are rarely reported. In this work, therefore, the complicated flow hardening or softening mechanisms during multi-stage warm (200 ºC) and hot (300 ºC and 400 ºC) deformation of the air-cooled (AC) and water-quenched (WQ) Al-Cu-Mg-Zr alloy after solution treatment were studied by means of isothermal (1, 2, 3, 6 passes) compression tests, microstructural characterization and in-situ electrical resistivity monitoring. During warm deformation at 200 ºC, clear flow hardening was presented until high strain level (0.8–1.0) for AC and WQ alloy, after which slight flow softening and hardening was observed due to the dynamic recovery caused by high strain energy, respectively. But the more the number of deformation pass, the stronger static hardening caused by static precipitation, leading to higher flow stress and enhancing the flow softening behaviors within high strain range (0.8–1.2). During hot deformation at 300 ºC and 400 ºC, the clear dynamic and static softening of AC and WQ alloy are mainly attributed to dynamic/static recovery (DRV and SRV) and precipitation, respectively. However, the strain energy consumed by static recovery and/or precipitation would increase significantly with rising number of static holding process. Consequently, the stored strain energy for the occurrence of DRV during later stage of deformation ( ε >0.8) was insufficient, leading to flow hardening of 3- and 6-pass deformation.
Complex dynamic and static softening behaviors in flow stress evolutions serve as important indicator for optimizing the power or load required by thermomechanical processes of Al-Cu-Mg alloys. However, the flow stress behaviors during the commonly employed industrial multi-stage warm and hot forming of Al-Cu-Mg alloys are rarely reported. In this work, therefore, the complicated flow hardening or softening mechanisms during multi-stage warm (200 ºC) and hot (300 ºC and 400 ºC) deformation of the air-cooled (AC) and water-quenched (WQ) Al-Cu-Mg-Zr alloy after solution treatment were studied by means of isothermal (1, 2, 3, 6 passes) compression tests, microstructural characterization and in-situ electrical resistivity monitoring. During warm deformation at 200 ºC, clear flow hardening was presented until high strain level (0.8–1.0) for AC and WQ alloy, after which slight flow softening and hardening was observed due to the dynamic recovery caused by high strain energy, respectively. But the more the number of deformation pass, the stronger static hardening caused by static precipitation, leading to higher flow stress and enhancing the flow softening behaviors within high strain range (0.8–1.2). During hot deformation at 300 ºC and 400 ºC, the clear dynamic and static softening of AC and WQ alloy are mainly attributed to dynamic/static recovery (DRV and SRV) and precipitation, respectively. However, the strain energy consumed by static recovery and/or precipitation would increase significantly with rising number of static holding process. Consequently, the stored strain energy for the occurrence of DRV during later stage of deformation ( ε >0.8) was insufficient, leading to flow hardening of 3- and 6-pass deformation.
期刊：
Journal of Solid State Chemistry,2025年345:125205 ISSN：0022-4596
通讯作者：
Huang, Jincheng;Peng, ZY
作者机构：
[Huang, Jincheng; Zhu, Yuxiang; Zhang, Yuanfang; Peng, Zhuoyin; Zhang, Xinlong; Li, Wei; Liao, Kai; Peng, ZY; Gu, Yongjie] Changsha Univ Sci & Technol, Hunan Prov Collaborat Innovat Ctr Clean Energy & S, Sch Energy & Power Engn, Educ Dept Hunan Prov, Changsha 410111, Peoples R China.;[Zhu, Yuxiang] Wuxi Municipal Bur Ind & Informat Technol, Wuxi, Peoples R China.
通讯机构：
[Huang, JC; Peng, ZY ] C;Changsha Univ Sci & Technol, Hunan Prov Collaborat Innovat Ctr Clean Energy & S, Sch Energy & Power Engn, Educ Dept Hunan Prov, Changsha 410111, Peoples R China.
关键词：
Carbon based PbS quantum dot solar cells;Direct one-step dual ligand passivation;Charge transfer;Photovoltaic performance
摘要：
The surface traps of quantum dots are still serious problems to limit the photovoltaic performance of carbon based quantum dot solar cells. In order to optimize the surface state of quantum dot solar cells, PbI 2 /MPA dual surface ligand is introduced for direct one-step surface passivation strategy to reduce the generated undercoordinated sites and OH group in PbS quantum dot solar cells, which can provide uniform, compact and stable structure for PbS thin films. The optical absorption and charge separation properties of carbon based PbS quantum dot solar cells have been improved under this PbI 2 /MPA dual surface ligand passivation process. The excellent trap passivation has effectively improved the charge transfer efficiency of the solar cells, which exhibits higher open-circuit voltage (25.33 mA/cm 2 ), short-circuit current density (507.8 mV) and fill factor (0.525) value for carbon based PbS quantum dot solar cells. As a result, photovoltaic conversion efficiency of carbon based PbS quantum dot solar cells has been enhanced from 5.36 % to 6.75 % under this direct one-step dual PbI 2 /MPA surface ligand passivation. This work provides an effective traps passivation process to further optimize the PbS quantum dots for optoelectronic devices applications.
The surface traps of quantum dots are still serious problems to limit the photovoltaic performance of carbon based quantum dot solar cells. In order to optimize the surface state of quantum dot solar cells, PbI 2 /MPA dual surface ligand is introduced for direct one-step surface passivation strategy to reduce the generated undercoordinated sites and OH group in PbS quantum dot solar cells, which can provide uniform, compact and stable structure for PbS thin films. The optical absorption and charge separation properties of carbon based PbS quantum dot solar cells have been improved under this PbI 2 /MPA dual surface ligand passivation process. The excellent trap passivation has effectively improved the charge transfer efficiency of the solar cells, which exhibits higher open-circuit voltage (25.33 mA/cm 2 ), short-circuit current density (507.8 mV) and fill factor (0.525) value for carbon based PbS quantum dot solar cells. As a result, photovoltaic conversion efficiency of carbon based PbS quantum dot solar cells has been enhanced from 5.36 % to 6.75 % under this direct one-step dual PbI 2 /MPA surface ligand passivation. This work provides an effective traps passivation process to further optimize the PbS quantum dots for optoelectronic devices applications.
摘要：
A new method was proposed for predicting residual stress in light alloys using truncated conical indentation. In this method, a truncated conical indenter with a cone angle of 120°, insensitive to edge-chamfer and friction effects, was used to test the residual stress of light alloys. Selecting the ratio of indentation work between stressed and unstressed specimens as an analytical parameter, a dimensionless truncated conical indentation (TCI) model related to the ratio of indentation work between stressed and unstressed, material properties, and normalized residual stress was established via dimensional analysis and numerical calculations. The TCI model could predict equi-biaxial residual stress and uniaxial residual stress, and its accuracy was verified in a wide range of light alloys with varying residual stress by numerical simulation. The stability of the TCI model is verified numerically by introducing errors in material parameters. Truncated conical indentation tests were conducted on cruciform specimens and rectangular specimens respectively made of three aluminum alloys. The results exhibited the residual stress predicted by proposed method agrees well with the applied stress, and the relative errors between them were within ±10 % in most cases.
A new method was proposed for predicting residual stress in light alloys using truncated conical indentation. In this method, a truncated conical indenter with a cone angle of 120°, insensitive to edge-chamfer and friction effects, was used to test the residual stress of light alloys. Selecting the ratio of indentation work between stressed and unstressed specimens as an analytical parameter, a dimensionless truncated conical indentation (TCI) model related to the ratio of indentation work between stressed and unstressed, material properties, and normalized residual stress was established via dimensional analysis and numerical calculations. The TCI model could predict equi-biaxial residual stress and uniaxial residual stress, and its accuracy was verified in a wide range of light alloys with varying residual stress by numerical simulation. The stability of the TCI model is verified numerically by introducing errors in material parameters. Truncated conical indentation tests were conducted on cruciform specimens and rectangular specimens respectively made of three aluminum alloys. The results exhibited the residual stress predicted by proposed method agrees well with the applied stress, and the relative errors between them were within ±10 % in most cases.
作者机构：
[Penghui Cao] College of Energy and Power Engineering, Changsha University of Science & Technology, Changsha, 410114 P. R. China;[Wen Liu; Qiwen Zhao; Siru He; Huaming Yu; Yang Li; Guichao Kuang; Yuejiao Chen; Libao Chen] State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083 P. R. China;[Bingang Xu] Nanotechnology Center, Research Institute for Intelligent Wearable Systems, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, 999077 P. R. China
通讯机构：
[Yuejiao Chen] S;State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083 P. R. China
摘要：
One of the important challenges in advancing aqueous zinc-ion batteries is the separator, which is crucial for promoting stable electrode-electrolyte interface and energy density of the battery. Herein, this study introduces a metal ion-activated air-laid paper (ALP Act) as an alternative for traditional glass fiber separators with big thickness and weight. Notably, the sustainable release of metal ions facilitates in situ interface engineering, thus creating a surface layer with high zinc affinity to promote the uniform migration and deposition of zinc ions. By continuously adjusting the electrode-electrolyte interface, the behaviors of dendrite growth and side reactions are effectively suppressed. Consequently, the ALP Act with continuous metal-ion release function enables the zinc anode to attain a 21-fold increase in running life beyond 3700 h compared with the conventional glass fiber separator at 1 mA cm −2 and l mAh cm −2 . The Zn||Cu battery also achieves a remarkable Coulombic efficiency of 99.18% for 2000 h (1 mA cm −2 /1 mAh cm −2 ). The assembled Zn||NVO battery exhibits a lifespan of 3000 cycles for the charge and discharge cycles at 3 A g −1 . This research offers a new avenue for the separator to achieve low-cost, long-lasting, and energy-dense aqueous zinc batteries.
摘要：
The thermocline latent heat packed bed system has the potential to be used for >200 °C high-temperature, 100–200 °C medium-temperature, and <100 °C low-temperature thermal energy storage applications. However, the inherent shortcoming of phase change material (PCM) is its low thermal conductivity, which inevitably restricts the heat transfer between the fillers and the heat transfer fluid. This study aims to investigate the thermal performance of the packed bed thermal energy storage (PBTES) system at mass flow rates of Re = 23-68 by filling the tank with high thermal conductivity composite PCM. An encapsulated expanded graphite/stearic acid composite PCM with a cylindrical aluminum shell was designed to prevent leakage and used as filler. The thermal conductivity of the composite is 305.7 % higher than that of pure PCM, demonstrating a higher thermal storage rate for a single capsule. Results show that this composite used as filler leads to a faster heat transfer rate between heat transfer fluid and solid fillers, decreasing the charging time by approximately 23.8 %, and keeping a more stable and distinct phase change platform at 55–60 °C. Moreover, an appropriate increase in the mass flow rate can facilitate heat transfer and improve the thermal performance of PBTES. Nevertheless, the thermal storage capacity utilization is reduced accordingly. Compared to the system with pure PCM fillers, the system with composite fillers exhibits a higher charging efficiency of 86.27 %, a higher stored thermal energy of 0.448 kWh, and a higher utilization rate at the threshold temperature. Overall, the thermal conductivity of filler is one of the primary parameters to determine the thermal performance of the thermocline latent heat packed bed system.
The thermocline latent heat packed bed system has the potential to be used for >200 °C high-temperature, 100–200 °C medium-temperature, and <100 °C low-temperature thermal energy storage applications. However, the inherent shortcoming of phase change material (PCM) is its low thermal conductivity, which inevitably restricts the heat transfer between the fillers and the heat transfer fluid. This study aims to investigate the thermal performance of the packed bed thermal energy storage (PBTES) system at mass flow rates of Re = 23-68 by filling the tank with high thermal conductivity composite PCM. An encapsulated expanded graphite/stearic acid composite PCM with a cylindrical aluminum shell was designed to prevent leakage and used as filler. The thermal conductivity of the composite is 305.7 % higher than that of pure PCM, demonstrating a higher thermal storage rate for a single capsule. Results show that this composite used as filler leads to a faster heat transfer rate between heat transfer fluid and solid fillers, decreasing the charging time by approximately 23.8 %, and keeping a more stable and distinct phase change platform at 55–60 °C. Moreover, an appropriate increase in the mass flow rate can facilitate heat transfer and improve the thermal performance of PBTES. Nevertheless, the thermal storage capacity utilization is reduced accordingly. Compared to the system with pure PCM fillers, the system with composite fillers exhibits a higher charging efficiency of 86.27 %, a higher stored thermal energy of 0.448 kWh, and a higher utilization rate at the threshold temperature. Overall, the thermal conductivity of filler is one of the primary parameters to determine the thermal performance of the thermocline latent heat packed bed system.
作者机构：
[Li, Xinzhuo; Tian, Hong; Sun, Liutao; Dai, Pengfei; Xu, Chenghui; Huang, Zhangjun; Li, XZ] Changsha Univ Sci & Technol, Sch Energy & Power Engn, Changsha 410114, Peoples R China.
通讯机构：
[Li, XZ ] C;Changsha Univ Sci & Technol, Sch Energy & Power Engn, Changsha 410114, Peoples R China.
关键词：
Ammonia/methane mixture combustion;Mechanism reduction;Mechanism optimization;Artificial Neural Network;NO x emissions
摘要：
The application of ammonia/methane (NH 3 /CH 4 ) blended fuels in gas turbines has received considerable attention, and the development of their combustors requires the implementation of more precise and compact reaction mechanisms. In this work, we propose a new optimization mechanism for ammonia/methane and comprehensively verify the performance of the optimization mechanism. A detailed chemical mechanism with 65 species and 466 reactions (Detailed-Mech) was first assembled using models from the literature. A directed relation graph with error propagation (DRGEP) and computational singular perturbation (CSP) method were then used to obtain a 23-species, 73-reaction compact reaction model (Reduced-Mech). Finally, the pre-exponential factor ( A ) and activation energy ( E a ) of five significant elementary reactions were optimized using an Artificial Neural Network (ANN) to obtain the optimized mechanism (ANN-Mech). The ANN-Mech was validated at ignition delay times (IDT), laminar burning velocity (LBV), plug flow reactor (PFR) species distribution, and in the 3-D combustion chamber. The study found that the logarithmic mean errors of IDT decreased by 3.9 %. The mean error of laminar burning velocity is reduced from 18.5 % to 9.5 %, and the prediction error of NO X in ANN-Mech is reduced by 47.5 %. The results of the premixed flames simulation indicate that the temperature and velocity fields of ANN-Mech at different ammonia fractions better agree with the Detailed-Mech. Additionally, the NO error of the outlet was reduced by 30 %. The calculation speed was also increased by ten times compared to the Detailed-Mech.
The application of ammonia/methane (NH 3 /CH 4 ) blended fuels in gas turbines has received considerable attention, and the development of their combustors requires the implementation of more precise and compact reaction mechanisms. In this work, we propose a new optimization mechanism for ammonia/methane and comprehensively verify the performance of the optimization mechanism. A detailed chemical mechanism with 65 species and 466 reactions (Detailed-Mech) was first assembled using models from the literature. A directed relation graph with error propagation (DRGEP) and computational singular perturbation (CSP) method were then used to obtain a 23-species, 73-reaction compact reaction model (Reduced-Mech). Finally, the pre-exponential factor ( A ) and activation energy ( E a ) of five significant elementary reactions were optimized using an Artificial Neural Network (ANN) to obtain the optimized mechanism (ANN-Mech). The ANN-Mech was validated at ignition delay times (IDT), laminar burning velocity (LBV), plug flow reactor (PFR) species distribution, and in the 3-D combustion chamber. The study found that the logarithmic mean errors of IDT decreased by 3.9 %. The mean error of laminar burning velocity is reduced from 18.5 % to 9.5 %, and the prediction error of NO X in ANN-Mech is reduced by 47.5 %. The results of the premixed flames simulation indicate that the temperature and velocity fields of ANN-Mech at different ammonia fractions better agree with the Detailed-Mech. Additionally, the NO error of the outlet was reduced by 30 %. The calculation speed was also increased by ten times compared to the Detailed-Mech.
作者机构：
[Zhang, Chipeng; Li, Wei; Zhou, Hui; Jiang, Dapeng; Bo, Guowei; Deng, Cuiling] Changsha Univ Sci & Technol, Coll Energy & Power Engn, Changsha 410114, Peoples R China.;[Bo, Guowei; Sun, Youping] Guangxi Univ Sci & Technol, Guangxi Key Lab Automobile Components & Vehicle Te, Liuzhou 545006, Peoples R China.;[Peng, ZR; Wang, Chenyang; Peng, Zirong; Bo, Guowei; Wang, CY] Tech Univ Munich, Chair Mat Engn Addit Mfg, Dept Mat Engn, Boltzmannstr 15, D-85748 Garching, Germany.;[Mao, Guoling] China North Engine Res Inst, Natl Key Lab Vehicle Power Syst, Tianjin 300400, Peoples R China.;[Jiang, Fulin] Hunan Univ, Coll Mat Sci & Engn, Changsha 410082, Peoples R China.
通讯机构：
[Mao, GL ] C;[Peng, ZR ; Wang, CY] T;Tech Univ Munich, Chair Mat Engn Addit Mfg, Dept Mat Engn, Boltzmannstr 15, D-85748 Garching, Germany.;China North Engine Res Inst, Natl Key Lab Vehicle Power Syst, Tianjin 300400, Peoples R China.
关键词：
Al-Si alloy;Microstructural classification;Automatic phase extraction;Unsupervised machine learing;Supervised deep learing
摘要：
Microstructural classification based on microscopic images are mostly done manually by human experts, which is time-consuming and generally leads to uncertainties due to subjectivity. In this work, machine learning and deep learning are used to automatically retrieve the useful morphology information of Si phase in Al-Si alloys which are widely used as various automotive components. Concretely, both clean mircographs without oxidization and noisy micrographs with oxidization are prepared under optical microscopy. Then an unsupervised machine learning algorithm (K-means clustering) is employed without manually labeled training data. The results show that a 92 % accuracy of extracting Si phase could be achieved on clean data, while only 75 % on noisy data. On the other hand, a supervised deep learning method (U-Net convolutional neural network) based on mixture of clean and noisy training dataset achieves high accuracy of recognizing Si phase in both clean (92 %) and noisy (87 %) micrographs. Meanwhile, the influence of the amount of training data and the proportion of the Si phase in training micrographs on the accuracy are also discussed. Further, when the training data used in U-Net method are labeled by K-means method instead of human efforts, U-Net method can achieve high accuracy in clean and noisy data.
Microstructural classification based on microscopic images are mostly done manually by human experts, which is time-consuming and generally leads to uncertainties due to subjectivity. In this work, machine learning and deep learning are used to automatically retrieve the useful morphology information of Si phase in Al-Si alloys which are widely used as various automotive components. Concretely, both clean mircographs without oxidization and noisy micrographs with oxidization are prepared under optical microscopy. Then an unsupervised machine learning algorithm (K-means clustering) is employed without manually labeled training data. The results show that a 92 % accuracy of extracting Si phase could be achieved on clean data, while only 75 % on noisy data. On the other hand, a supervised deep learning method (U-Net convolutional neural network) based on mixture of clean and noisy training dataset achieves high accuracy of recognizing Si phase in both clean (92 %) and noisy (87 %) micrographs. Meanwhile, the influence of the amount of training data and the proportion of the Si phase in training micrographs on the accuracy are also discussed. Further, when the training data used in U-Net method are labeled by K-means method instead of human efforts, U-Net method can achieve high accuracy in clean and noisy data.
摘要：
The global shortage of fresh-water resources is becoming increasingly serious, while the photothermal evaporation has a broad application in the desalination of seawater. However, the physical modeling for photothermal evaporation is not perfect enough to support further improvement of the evaporation performance of photothermal materials. In this study, a photothermal evaporation model using Ti 3 C 2 -wood as a photothermal material is established. The impact of various external environmental factors, including light intensity, initial ambient temperature and air humidity, on the evaporation performance of photothermal materials has been investigated. Additionally, an internal relationship is created between the photothermal material's evaporation behavior and its physical properties, such as thermal conductivity, surface absorbance, and material thickness. On the basis of analytical research, some conclusions have been demonstrated that the evaporative properties of photothermal materials are positively correlated with light intensity and initial ambient temperature, but opposite to air humidity. Besides, the evaporation performance of photothermal materials is generally enhanced by increases in thermal conductivity, surface absorbance and material thickness. Moreover, it should be pointed out that the numerical analysis indicates if the photothermal material's thickness goes above a particular range, it may lead to insufficient water supply, thereby suppressing the evaporation rate conversely. This work can provide theoretical guidance for exploring the methods to enhance the photothermal material's evaporation performance, which is of great significance to solve the increasingly serious problem of the lack of fresh-water resources.
The global shortage of fresh-water resources is becoming increasingly serious, while the photothermal evaporation has a broad application in the desalination of seawater. However, the physical modeling for photothermal evaporation is not perfect enough to support further improvement of the evaporation performance of photothermal materials. In this study, a photothermal evaporation model using Ti 3 C 2 -wood as a photothermal material is established. The impact of various external environmental factors, including light intensity, initial ambient temperature and air humidity, on the evaporation performance of photothermal materials has been investigated. Additionally, an internal relationship is created between the photothermal material's evaporation behavior and its physical properties, such as thermal conductivity, surface absorbance, and material thickness. On the basis of analytical research, some conclusions have been demonstrated that the evaporative properties of photothermal materials are positively correlated with light intensity and initial ambient temperature, but opposite to air humidity. Besides, the evaporation performance of photothermal materials is generally enhanced by increases in thermal conductivity, surface absorbance and material thickness. Moreover, it should be pointed out that the numerical analysis indicates if the photothermal material's thickness goes above a particular range, it may lead to insufficient water supply, thereby suppressing the evaporation rate conversely. This work can provide theoretical guidance for exploring the methods to enhance the photothermal material's evaporation performance, which is of great significance to solve the increasingly serious problem of the lack of fresh-water resources.
期刊：
Journal of Alloys and Compounds,2025年1021:179708 ISSN：0925-8388
通讯作者：
Wei Chen<&wdkj&>Yongcheng Lin
作者机构：
[Wei Chen; Xinru Xu; Wei Qiu; Lang Gan; Kang Chen; Cong Li; Jian Chen] School of Energy and Power Engineering, Changsha University of Science & Technology, Changsha, Hunan 410114, China;[Peipei Jiang] School of Resources Environment and Safety Engineering, University of South China, Hengyang, Hunan 421001, China;[Daoguang He; Yongcheng Lin] School of Mechanical and Electrical Engineering, Central South University, Changsha, Hunan 410083, China
通讯机构：
[Wei Chen; Yongcheng Lin] S;School of Mechanical and Electrical Engineering, Central South University, Changsha, Hunan 410083, China<&wdkj&>School of Energy and Power Engineering, Changsha University of Science & Technology, Changsha, Hunan 410114, China
摘要：
This study examines the impact of the rare earth oxide La 2 O 3 on the microstructure, mechanical and corrosion resistance properties of as-cast Al-Si-Mg (A356) alloys, with a specific focus on the A356 alloy. By incorporating varying amounts of La 2 O 3 (0 wt%, 0.2 wt%, 0.3 wt%, and 0.4 wt%) into the A356 alloy, four samples (AL0, AL2, AL3, and AL4) were produced. The findings demonstrate that an optimal addition of La 2 O 3 (0.3 wt%) can effectively reduce the secondary dendrite arm spacing (SDAS), refine the eutectic Si phase, and modify the morphology of Fe-rich phases, thereby significantly enhancing the overall performance of the alloy. The transformation in the morphology of the Fe-rich phases is accompanied by changes in their elemental composition, including the transition from elongated rod-like AlFeSi phases to shorter rod-like Al 7 Fe 6 La phases. Specifically, the AL3 sample displays the best mechanical properties, with increases in hardness, yield strength (YS), ultimate tensile strength (UTS) and elongation (EL) of 11.11 %, 71.43 %, 36.45 % and 233.46 %, respectively. Moreover, AL3 exhibits superior corrosion resistance, characterized by the highest corrosion potential (-0.88 V) and the lowest corrosion current density (3.6 ×10 −7 A/cm 2 ). The addition of La 2 O 3 promotes grain refinement, reduces the size of secondary phase particles, and the formation of Al 7 Fe 6 La phase collectively contributing to the enhanced performance of the A356 alloy. The present study provides theoretical support for utilizing rare earth oxides as a viable alternative to pure rare earth metals in Al alloys, presenting a cost-efficient strategy tailored for industrial implementations.
This study examines the impact of the rare earth oxide La 2 O 3 on the microstructure, mechanical and corrosion resistance properties of as-cast Al-Si-Mg (A356) alloys, with a specific focus on the A356 alloy. By incorporating varying amounts of La 2 O 3 (0 wt%, 0.2 wt%, 0.3 wt%, and 0.4 wt%) into the A356 alloy, four samples (AL0, AL2, AL3, and AL4) were produced. The findings demonstrate that an optimal addition of La 2 O 3 (0.3 wt%) can effectively reduce the secondary dendrite arm spacing (SDAS), refine the eutectic Si phase, and modify the morphology of Fe-rich phases, thereby significantly enhancing the overall performance of the alloy. The transformation in the morphology of the Fe-rich phases is accompanied by changes in their elemental composition, including the transition from elongated rod-like AlFeSi phases to shorter rod-like Al 7 Fe 6 La phases. Specifically, the AL3 sample displays the best mechanical properties, with increases in hardness, yield strength (YS), ultimate tensile strength (UTS) and elongation (EL) of 11.11 %, 71.43 %, 36.45 % and 233.46 %, respectively. Moreover, AL3 exhibits superior corrosion resistance, characterized by the highest corrosion potential (-0.88 V) and the lowest corrosion current density (3.6 ×10 −7 A/cm 2 ). The addition of La 2 O 3 promotes grain refinement, reduces the size of secondary phase particles, and the formation of Al 7 Fe 6 La phase collectively contributing to the enhanced performance of the A356 alloy. The present study provides theoretical support for utilizing rare earth oxides as a viable alternative to pure rare earth metals in Al alloys, presenting a cost-efficient strategy tailored for industrial implementations.
通讯机构：
[Huang, JC; Peng, ZY ] C;Changsha Univ Sci & Technol, Sch Energy & Power Engn, Key Lab Efficient & Clean Energy Utilizat, Changsha 410111, Peoples R China.
摘要：
Despite the advancements in film fabrication techniques for emerging perovskite solar cells, achieving a high-quality film by solution processing, while maintaining considerable performance remains a significant challenge. To tackle the issue of inferior CsPbI2Br perovskite films deposited via solution-based methods, a novel thermal conduction heating approach was devised and implemented, significantly enhancing film uniformity. Crucially, aliphatic amine acetates (3A) were introduced into the precursor solution to regulate the crystallization process and therefore to mitigate defects. Systematic investigation into the impact of 3A molecules featuring varying alkyl chain lengths on defect passivation revealed that the molecular dipole moment of these additives contributed to both defect mitigation and grain size refinement. Notably, the integration of alkyl chains significantly bolstered the hydrophobic properties of the perovskite film. Consequently, an impressive efficiency of 13.50% for HTM-free carbon-based CsPbI2Br perovskite solar cells was achieved, and the device exhibited robust stability retaining 92.4% of its initial efficiency at room temperature after being stored in dry air for 5400 h. This research offers profound insights into defect passivation mechanisms and perovskite crystallization dynamics, paving the way for further advancements in the field of perovskite solar cell technology.
摘要：
In microscale structures, thermal and viscous effects are important factors affecting the effective transmission of acoustic energy. In this paper, the effects of porosity, single thermal effect, single viscous effect, and thermoviscous coupling on the acoustic energy transmission characteristics of microcolumn arrays are analyzed in detail by numerical solution of thermoviscous acoustic equations. The effects of temperature on thermal effect and viscous effects are discussed. The results show that the nonlinear coupling effect of thermal and viscous effects contributes the most to acoustic energy dissipation, and the viscous effect is much greater than that of the thermal effect. Compared with the case without thermoviscous dissipation, when a frequency of 7000 Hz sound wave propagates in a microcolumn array with a porosity of 0.5, the thermal viscous coupling effect, single viscous effect, and single thermal effect respectively reduce the sound transmission coefficient by about 33 %, 27.25 %, and 8.44 %. The transmission coefficient of acoustic energy decreases with the decrease of microcolumn array porosity. With the increase in temperature, the acoustic energy transmission loss curve shifts to high frequency, which is conducive to weakening the influence of the viscous dissipation effect on acoustic energy loss. The results are significant for understanding the sound transmission mechanism in microstructures.
In microscale structures, thermal and viscous effects are important factors affecting the effective transmission of acoustic energy. In this paper, the effects of porosity, single thermal effect, single viscous effect, and thermoviscous coupling on the acoustic energy transmission characteristics of microcolumn arrays are analyzed in detail by numerical solution of thermoviscous acoustic equations. The effects of temperature on thermal effect and viscous effects are discussed. The results show that the nonlinear coupling effect of thermal and viscous effects contributes the most to acoustic energy dissipation, and the viscous effect is much greater than that of the thermal effect. Compared with the case without thermoviscous dissipation, when a frequency of 7000 Hz sound wave propagates in a microcolumn array with a porosity of 0.5, the thermal viscous coupling effect, single viscous effect, and single thermal effect respectively reduce the sound transmission coefficient by about 33 %, 27.25 %, and 8.44 %. The transmission coefficient of acoustic energy decreases with the decrease of microcolumn array porosity. With the increase in temperature, the acoustic energy transmission loss curve shifts to high frequency, which is conducive to weakening the influence of the viscous dissipation effect on acoustic energy loss. The results are significant for understanding the sound transmission mechanism in microstructures.
期刊：
Solar Energy Materials and Solar Cells,2025年286:113531 ISSN：0927-0248
通讯作者：
Huan Zhang
作者机构：
[Jiandi Ren; Sheng Xiao; Huan Zhang; Jianlin Chen] School of Energy and Power Engineering, Changsha University of Science and Technology, 410114, Changsha, China;School of Traffic and Transportation Engineering, Changsha University of Science and Technology, 410114, Changsha, China;[Yanjie Ren] School of Mechanical and Energy Engineering, Zhejiang University of Science and Technology, 310023, Hangzhou, China;CAS Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, 510640, Guangzhou, China;[Changhui Liu] School of Low-Carbon Energy and Power Engineering, China University of Mining and Technology, 221116, Xuzhou, China
通讯机构：
[Huan Zhang] S;School of Energy and Power Engineering, Changsha University of Science and Technology, 410114, Changsha, China
摘要：
The molten salt thermal energy storage system is the most important composition of concentrating solar power plants, resulting in the corrosion behavior of alloys in molten salts is essential to be analyzed to ensure the long-term stability of the system. In this study, the corrosion behavior of TP347H stainless steel, Haynes230 and Inconel625 alloys was investigated in a self-developed novel molten chloride salt (24.5 wt% NaCl-8.2 wt% KCl-67.3 wt% CaCl 2 ). The corrosion mechanism of the alloy samples in molten chloride salts was analyzed through the microscopic characterization and elemental analysis tests. The evolution of alloy sample mass loss versus corrosion time and the main influential factors of the corrosion were analyzed. Corrosion pits appear on the surface of the alloy samples with the increasing corrosion time. Distinct corrosion cracks is observed that on the surface of the Inconel625 sample. Under the condition of 600 °C, the average corrosion rate of TP347H stainless steels is2383.628 μm·a −1 , and those of Haynes230 and Inconel625 are 487.639 μm·a −1 and 5437.520 μm·a −1 . The protective oxide layer within TP347H stainless steels corrosion layer effectively inhibited further matrix corrosion. The superior corrosion resistance of Haynes230 can be attributed to its higher Ni and W content. These results are significant for optimizing the usage of novel molten salts and alloys to achieve long-term stability of the concentrating solar power plants.
The molten salt thermal energy storage system is the most important composition of concentrating solar power plants, resulting in the corrosion behavior of alloys in molten salts is essential to be analyzed to ensure the long-term stability of the system. In this study, the corrosion behavior of TP347H stainless steel, Haynes230 and Inconel625 alloys was investigated in a self-developed novel molten chloride salt (24.5 wt% NaCl-8.2 wt% KCl-67.3 wt% CaCl 2 ). The corrosion mechanism of the alloy samples in molten chloride salts was analyzed through the microscopic characterization and elemental analysis tests. The evolution of alloy sample mass loss versus corrosion time and the main influential factors of the corrosion were analyzed. Corrosion pits appear on the surface of the alloy samples with the increasing corrosion time. Distinct corrosion cracks is observed that on the surface of the Inconel625 sample. Under the condition of 600 °C, the average corrosion rate of TP347H stainless steels is2383.628 μm·a −1 , and those of Haynes230 and Inconel625 are 487.639 μm·a −1 and 5437.520 μm·a −1 . The protective oxide layer within TP347H stainless steels corrosion layer effectively inhibited further matrix corrosion. The superior corrosion resistance of Haynes230 can be attributed to its higher Ni and W content. These results are significant for optimizing the usage of novel molten salts and alloys to achieve long-term stability of the concentrating solar power plants.
作者机构：
[Wei Chen; Chenyang Gong; Lang Gan; Cong Li; Jian Chen; Wei Qiu] School of Energy and Power Engineering, Changsha University of Science & Technology, Changsha 410114, China;[Peipei Jiang] School of Resources Environment and Safety Engineering, University of South China, Hengyang 421001, China;[Yanjie Ren] School of Mechanical & Energy Engineering, Zhejiang University of Science & Technology, Hangzhou 310023, China
通讯机构：
[Wei Chen; Wei Qiu] S;School of Energy and Power Engineering, Changsha University of Science & Technology, Changsha 410114, China
摘要：
This study delved into the corrosion behavior of ZK60 Mg alloy in saturated NaCl solution, particularly focusing on the effects of the addition of rare earth oxide, namely CeO 2 (forming ZKC alloy) and La 2 O 3 (forming ZKL alloy). The results indicate that the introduction of CeO 2 and La 2 O 3 promotes the precipitation of T-(Mg 1− x , Zn x ) 11 RE phases (Mg-Zn-RE phases, where RE represents Ce or La) at grain boundaries. The presence and distribution pattern of the T-phase have a profound impact on the corrosion resistance of the Mg alloy. Specifically, the ZKC alloy exhibits the most outstanding corrosion resistance. This superior performance is attributed to the uniform distribution of (Mg 1− x , Zn x ) 11 Ce phase at grain boundaries in ZK60-0.5 wt% CeO 2 , effectively hindering the penetration of corrosive media into the matrix. Additionally, scanning kelvin probe force microscopy (SKPFM) analysis reveals that the (Mg 1− x , Zn x ) 11 Ce phase exhibits the smallest potential difference with the matrix, significantly mitigating the tendency for galvanic corrosion. In contrast, the ZKL alloy displays less precipitation and uneven distribution of the (Mg 1− x , Zn x ) 11 La phase, resulting in inferior corrosion resistance compared to the ZKC alloy. The disparities in the precipitation of the two phases, as derived from first-principles calculations, stem from the spontaneous reduction of CeO 2 under Mg conditions, whereas the reduction reaction between La 2 O 3 and Mg cannot proceed spontaneously. Furthermore, SKPFM analysis and CALPHAD method found that as the addition of CeO 2 /La 2 O 3 increases, the atomic ratio of Zn in the Mg-Zn-RE ternary phase rises, accompanied by an increase in the potential difference between the Mg-Zn-RE phase and the Mg matrix. This suggests that fine-tuning the addition of rare earth oxides can modify the atomic ratio of the Mg-Zn-RE ternary phase, thereby enhancing the corrosion resistance of the Mg alloy. In summary, this study not only unravels the specific mechanisms of how CeO 2 and La 2 O 3 affect the corrosion behavior of ZK60 Mg alloy but also provides new strategies and insights for the development of low-cost, high-performance corrosion-resistant Mg alloy materials.
This study delved into the corrosion behavior of ZK60 Mg alloy in saturated NaCl solution, particularly focusing on the effects of the addition of rare earth oxide, namely CeO 2 (forming ZKC alloy) and La 2 O 3 (forming ZKL alloy). The results indicate that the introduction of CeO 2 and La 2 O 3 promotes the precipitation of T-(Mg 1− x , Zn x ) 11 RE phases (Mg-Zn-RE phases, where RE represents Ce or La) at grain boundaries. The presence and distribution pattern of the T-phase have a profound impact on the corrosion resistance of the Mg alloy. Specifically, the ZKC alloy exhibits the most outstanding corrosion resistance. This superior performance is attributed to the uniform distribution of (Mg 1− x , Zn x ) 11 Ce phase at grain boundaries in ZK60-0.5 wt% CeO 2 , effectively hindering the penetration of corrosive media into the matrix. Additionally, scanning kelvin probe force microscopy (SKPFM) analysis reveals that the (Mg 1− x , Zn x ) 11 Ce phase exhibits the smallest potential difference with the matrix, significantly mitigating the tendency for galvanic corrosion. In contrast, the ZKL alloy displays less precipitation and uneven distribution of the (Mg 1− x , Zn x ) 11 La phase, resulting in inferior corrosion resistance compared to the ZKC alloy. The disparities in the precipitation of the two phases, as derived from first-principles calculations, stem from the spontaneous reduction of CeO 2 under Mg conditions, whereas the reduction reaction between La 2 O 3 and Mg cannot proceed spontaneously. Furthermore, SKPFM analysis and CALPHAD method found that as the addition of CeO 2 /La 2 O 3 increases, the atomic ratio of Zn in the Mg-Zn-RE ternary phase rises, accompanied by an increase in the potential difference between the Mg-Zn-RE phase and the Mg matrix. This suggests that fine-tuning the addition of rare earth oxides can modify the atomic ratio of the Mg-Zn-RE ternary phase, thereby enhancing the corrosion resistance of the Mg alloy. In summary, this study not only unravels the specific mechanisms of how CeO 2 and La 2 O 3 affect the corrosion behavior of ZK60 Mg alloy but also provides new strategies and insights for the development of low-cost, high-performance corrosion-resistant Mg alloy materials.
作者机构：
[Qinghang Wang; Xu Qin; Shouxin Xia; Li Wang] School of Mechanical Engineering, Yangzhou University, Yangzhou 225127, China;[Weiqi Wang] School of Materials and Energy, Yunnan University, Kunming 650599, China;[Weiying Huang] Institute of Energy and Power Engineering, Changsha University of Science and Technology, Changsha 410083, China;[Yan Song] Department of Components and Materials Test & Evaluation Research Center, China Automotive Engineering Research Institute (CAERI), Chongqing 401122, China;[Weineng Tang] Technology Center, Baosteel Metal Co., Ltd, Shanghai 200940, China
通讯机构：
[Qinghang Wang] S;School of Mechanical Engineering, Yangzhou University, Yangzhou 225127, China
摘要：
The application of machine learning in alloy design is increasingly widespread, yet traditional models still face challenges when dealing with limited datasets and complex nonlinear relationships. This work proposes an interpretable machine learning method based on data augmentation and reconstruction, excavating high-performance low-alloyed magnesium (Mg) alloys. The data augmentation technique expands the original dataset through Gaussian noise. The data reconstruction method reorganizes and transforms the original data to extract more representative features, significantly improving the model's generalization ability and prediction accuracy, with a coefficient of determination (R 2 ) of 95.9 % for the ultimate tensile strength (UTS) model and a R 2 of 95.3 % for the elongation-to-failure (EL) model. The correlation coefficient assisted screening (CCAS) method is proposed to filter low-alloyed target alloys. A new Mg-2.2Mn-0.4Zn-0.2Al-0.2Ca (MZAX2000, wt%) alloy is designed and extruded into bar at given processing parameters, achieving room-temperature strength-ductility synergy showing an excellent UTS of 395 MPa and a high EL of 17.9 %. This is closely related to its hetero-structured characteristic in the as-extruded MZAX2000 alloy consisting of coarse grains (16 %), fine grains (75 %), and fiber regions (9 %). Therefore, this work offers new insights into optimizing alloy compositions and processing parameters for attaining new high strong and ductile low-alloyed Mg alloys.
The application of machine learning in alloy design is increasingly widespread, yet traditional models still face challenges when dealing with limited datasets and complex nonlinear relationships. This work proposes an interpretable machine learning method based on data augmentation and reconstruction, excavating high-performance low-alloyed magnesium (Mg) alloys. The data augmentation technique expands the original dataset through Gaussian noise. The data reconstruction method reorganizes and transforms the original data to extract more representative features, significantly improving the model's generalization ability and prediction accuracy, with a coefficient of determination (R 2 ) of 95.9 % for the ultimate tensile strength (UTS) model and a R 2 of 95.3 % for the elongation-to-failure (EL) model. The correlation coefficient assisted screening (CCAS) method is proposed to filter low-alloyed target alloys. A new Mg-2.2Mn-0.4Zn-0.2Al-0.2Ca (MZAX2000, wt%) alloy is designed and extruded into bar at given processing parameters, achieving room-temperature strength-ductility synergy showing an excellent UTS of 395 MPa and a high EL of 17.9 %. This is closely related to its hetero-structured characteristic in the as-extruded MZAX2000 alloy consisting of coarse grains (16 %), fine grains (75 %), and fiber regions (9 %). Therefore, this work offers new insights into optimizing alloy compositions and processing parameters for attaining new high strong and ductile low-alloyed Mg alloys.
摘要：
Effective temperature regulation is critical for optimizing battery performance, especially under diverse climate conditions. This article presents an all-climate thermal management system for battery which integrates heat pipe and phase change material (PCM). The system’s performance is evaluated through numerical simulations. Utilizing phase change materials for heat storage and thermal insulation materials for heat preservation, the battery pack temperature can be maintained above 20 °C for extended periods in cold environments. Specifically, employing sodium carbonate decahydrate as the phase change material and a 15 mm thick aerogel insulation layer, the system sustains temperatures above 20 °C for approximately 4 h at −40 °C, nearly 6 h at −20 °C, and nearly 10 h at 0 °C. Additionally, the combination of the insulation layer and phase change materials helps reduce the temperature difference between the batteries within the battery pack. At room temperature, the un-melted phase change material can absorb the heat generated during the battery discharge process, thereby eliminating the need for additional cooling energy. In high-temperature scenarios where phase change materials reach their melting point, heat pipes play a crucial role in dissipating excess heat. When the battery’s discharge rate is below 1C, air can effectively serve as a cooling medium. However, as the discharge rate increases to 2C, a more efficient heat transfer medium such as water is necessary. To ensure the battery temperature stays below 40 °C when the ambient temperature reaches 40 °C or higher, it is recommended to set the temperature of the cooling medium below 35 °C. In conclusion, the proposed thermal management system in this article demonstrates effective thermal regulation performance across environments with temperatures ranging from −40 °C to 40 °C.
Effective temperature regulation is critical for optimizing battery performance, especially under diverse climate conditions. This article presents an all-climate thermal management system for battery which integrates heat pipe and phase change material (PCM). The system’s performance is evaluated through numerical simulations. Utilizing phase change materials for heat storage and thermal insulation materials for heat preservation, the battery pack temperature can be maintained above 20 °C for extended periods in cold environments. Specifically, employing sodium carbonate decahydrate as the phase change material and a 15 mm thick aerogel insulation layer, the system sustains temperatures above 20 °C for approximately 4 h at −40 °C, nearly 6 h at −20 °C, and nearly 10 h at 0 °C. Additionally, the combination of the insulation layer and phase change materials helps reduce the temperature difference between the batteries within the battery pack. At room temperature, the un-melted phase change material can absorb the heat generated during the battery discharge process, thereby eliminating the need for additional cooling energy. In high-temperature scenarios where phase change materials reach their melting point, heat pipes play a crucial role in dissipating excess heat. When the battery’s discharge rate is below 1C, air can effectively serve as a cooling medium. However, as the discharge rate increases to 2C, a more efficient heat transfer medium such as water is necessary. To ensure the battery temperature stays below 40 °C when the ambient temperature reaches 40 °C or higher, it is recommended to set the temperature of the cooling medium below 35 °C. In conclusion, the proposed thermal management system in this article demonstrates effective thermal regulation performance across environments with temperatures ranging from −40 °C to 40 °C.
作者机构：
[Peng Yuan; Ning Zhang] Dong Guan Cham Battery Technology Co., Ltd. Dongguan 523808, Guangdong, China;[Tao Zhang; Zuoyu Qin; Yuanhang Gao; Xiang Long; Zuosu Qin; Gen Chen] School of Materials Science and Engineering, Hunan Provincial Key Laboratory of Electronic Packaging and Advanced Functional Materials, Central South University, Changsha, Hunan 410083, P. R. China;[Chuankun Jia] College of Energy and Power Engineering, Changsha University of Science and Technology, Changsha 410114, P. R. China
通讯机构：
[Gen Chen] S;School of Materials Science and Engineering, Hunan Provincial Key Laboratory of Electronic Packaging and Advanced Functional Materials, Central South University, Changsha, Hunan 410083, P. R. China
关键词：
spent batteries;degraded cathodes;direct regeneration;molten salts;high temperature
摘要：
Within the framework of carbon neutrality, lithium-ion batteries (LIBs) are progressively booming along with the growing utilization of green and clean energy. However, the extensive application of LIBs with limited lifespan has brought about a significant recycling dilemma. The traditional hydrometallurgical or pyrometallurgical strategies are not capable to maximize the output value of spent LIBs and minimize the potential environmental hazards. Herein, to alternate the tedious and polluting treatment processes, we propose a high-temperature molten-salt strategy to directly regenerate spent cathodes of LIBs, which can also overcome the barrier of the incomplete defects’ restoration with previous low-temperature molten salts. The high-energy and stable medium environment ensures a more thorough and efficient relithiation reaction, and simultaneously provides sufficient driving force for atomic rearrangement and grains secondary growth. In consequence, the regenerated ternary cathode (R-NCM) exhibits significantly enhanced structural stability that effectively suppresses the occurrence of cracks and harmful side reactions. The R-NCM delivers excellent cycling stability, retaining 81.2% of its capacity after 200 cycles at 1 C. This technique further optimizes the traditional eutectic molten-salt approach, broadening its applicability and improving regenerated cathode performance across a wider range of conditions.
Within the framework of carbon neutrality, lithium-ion batteries (LIBs) are progressively booming along with the growing utilization of green and clean energy. However, the extensive application of LIBs with limited lifespan has brought about a significant recycling dilemma. The traditional hydrometallurgical or pyrometallurgical strategies are not capable to maximize the output value of spent LIBs and minimize the potential environmental hazards. Herein, to alternate the tedious and polluting treatment processes, we propose a high-temperature molten-salt strategy to directly regenerate spent cathodes of LIBs, which can also overcome the barrier of the incomplete defects’ restoration with previous low-temperature molten salts. The high-energy and stable medium environment ensures a more thorough and efficient relithiation reaction, and simultaneously provides sufficient driving force for atomic rearrangement and grains secondary growth. In consequence, the regenerated ternary cathode (R-NCM) exhibits significantly enhanced structural stability that effectively suppresses the occurrence of cracks and harmful side reactions. The R-NCM delivers excellent cycling stability, retaining 81.2% of its capacity after 200 cycles at 1 C. This technique further optimizes the traditional eutectic molten-salt approach, broadening its applicability and improving regenerated cathode performance across a wider range of conditions.
摘要：
High-speed extrudability is critical for the efficient production of metallic extruded products. This study employs a differential-thermal (DT) extrusion method to achieve an ultra-high extrusion speed of 83 m/min for the newly developed Mg-5Bi-3Al-1Zn (BAZ531, wt%) alloy while maintaining good surface quality. Finite element simulations confirmed that the DT extrusion heat remained below the alloy's initial melting point, preventing surface cracks. The DT process refined the average grain size to 15.2 μm, 0.6 times that of the equal-thermal (ET) extruded alloy, by delaying dynamic recrystallization due to a lower temperature increase. The BAZ531-DT alloy exhibited excellent mechanical properties, with a tensile yield strength of 283 MPa, ultimate tensile strength of 331 MPa, and elongation-to-failure of 19 %. Grain refinement and strong texture enhanced strength, while refined grains improved ductility by effectively suppressing twinning. This work demonstrates significant potential for advancing high-speed extrusion of Mg-Bi-based alloys with superior mechanical performance.
High-speed extrudability is critical for the efficient production of metallic extruded products. This study employs a differential-thermal (DT) extrusion method to achieve an ultra-high extrusion speed of 83 m/min for the newly developed Mg-5Bi-3Al-1Zn (BAZ531, wt%) alloy while maintaining good surface quality. Finite element simulations confirmed that the DT extrusion heat remained below the alloy's initial melting point, preventing surface cracks. The DT process refined the average grain size to 15.2 μm, 0.6 times that of the equal-thermal (ET) extruded alloy, by delaying dynamic recrystallization due to a lower temperature increase. The BAZ531-DT alloy exhibited excellent mechanical properties, with a tensile yield strength of 283 MPa, ultimate tensile strength of 331 MPa, and elongation-to-failure of 19 %. Grain refinement and strong texture enhanced strength, while refined grains improved ductility by effectively suppressing twinning. This work demonstrates significant potential for advancing high-speed extrusion of Mg-Bi-based alloys with superior mechanical performance.
摘要：
In the study, a novel photodeposition one-step method for preparing Cu/TiO2 photothermal catalysis was proposed to catalyze hydrogen production from glycerol. The biomass glycerol was used as a sacrificial agent to provide electrons for Cu2+ loading during the catalyst preparation stage, and the remaining biomass glycerol was used directly as a reactant for photothermal-catalyzed hydrogen production. The catalysts were characterized using XRD, SEM, and TEM to obtain their phases and structures. The Cu/TiO2 photodeposition process evaluation method based on image analysis and processing, and its experimental platform were established. The influence of parameters such as irradiation intensity, temperature, and catalyst concentration on the loading rate of photodeposited Cu2+ was analyzed. The results demonstrated that enhancing the irradiation intensity, increasing the temperature, and decreasing the catalyst concentration can increase the loading rate of Cu. The Cu/TiO2 photothermal catalyst prepared by this method showed a hydrogen production rate 1.6 times higher than that of the deposition and precipitation method under the same reaction conditions, which proved that the catalyst had a high photothermal catalysis hydrogen production activity. The hydrogen production rate at an irradiation intensity of 250 mW/cm2 was 628.16 μmol/(g·h), which was 1.9 times that at an irradiation intensity of 100 mW/cm2. Both elevated temperature and increased irradiation intensity can significantly improve the photothermal catalysis glycerol hydrogen production activity.
In the study, a novel photodeposition one-step method for preparing Cu/TiO2 photothermal catalysis was proposed to catalyze hydrogen production from glycerol. The biomass glycerol was used as a sacrificial agent to provide electrons for Cu2+ loading during the catalyst preparation stage, and the remaining biomass glycerol was used directly as a reactant for photothermal-catalyzed hydrogen production. The catalysts were characterized using XRD, SEM, and TEM to obtain their phases and structures. The Cu/TiO2 photodeposition process evaluation method based on image analysis and processing, and its experimental platform were established. The influence of parameters such as irradiation intensity, temperature, and catalyst concentration on the loading rate of photodeposited Cu2+ was analyzed. The results demonstrated that enhancing the irradiation intensity, increasing the temperature, and decreasing the catalyst concentration can increase the loading rate of Cu. The Cu/TiO2 photothermal catalyst prepared by this method showed a hydrogen production rate 1.6 times higher than that of the deposition and precipitation method under the same reaction conditions, which proved that the catalyst had a high photothermal catalysis hydrogen production activity. The hydrogen production rate at an irradiation intensity of 250 mW/cm2 was 628.16 μmol/(g·h), which was 1.9 times that at an irradiation intensity of 100 mW/cm2. Both elevated temperature and increased irradiation intensity can significantly improve the photothermal catalysis glycerol hydrogen production activity.
摘要：
Load deviations between the output of ultra-supercritical (USC) coal-fired power units and automatic generation control (AGC) commands can adversely affect the safe and stable operation of these units and grid load dispatching. Data-driven diagnostic methods often fail to account for the imbalanced distribution of data samples, leading to reduced classification performance in diagnosing load deviations in USC units. To address the class imbalance issue in USC load deviation datasets, this study proposes a diagnostic method based on the multi-label natural neighbor boundary oversampling technique (MLNaNBDOS). The method is articulated in three phases. Initially, the traditional binary oversampling strategy is improved by constructing a binary multi-label relationship for the load deviations in coal-fired units. Subsequently, an adaptive adjustment of the oversampling factor is implemented to determine the oversampling weight for each sample class. Finally, the generation of new instances is refined by dynamically evaluating the similarity between new cases and natural neighbors through a random factor, ensuring precise control over the instance generation process. In comparisons with nine benchmark methods across three imbalanced USC load deviation datasets, the proposed method demonstrates superior performance on several key evaluation metrics, including Micro-F 1, Micro-G-mean , and Hamming Loss , with average values of 0.8497, 0.9150, and 0.1503, respectively. These results substantiate the effectiveness of the proposed method in accurately diagnosing the sources of load deviations in USC units.
Load deviations between the output of ultra-supercritical (USC) coal-fired power units and automatic generation control (AGC) commands can adversely affect the safe and stable operation of these units and grid load dispatching. Data-driven diagnostic methods often fail to account for the imbalanced distribution of data samples, leading to reduced classification performance in diagnosing load deviations in USC units. To address the class imbalance issue in USC load deviation datasets, this study proposes a diagnostic method based on the multi-label natural neighbor boundary oversampling technique (MLNaNBDOS). The method is articulated in three phases. Initially, the traditional binary oversampling strategy is improved by constructing a binary multi-label relationship for the load deviations in coal-fired units. Subsequently, an adaptive adjustment of the oversampling factor is implemented to determine the oversampling weight for each sample class. Finally, the generation of new instances is refined by dynamically evaluating the similarity between new cases and natural neighbors through a random factor, ensuring precise control over the instance generation process. In comparisons with nine benchmark methods across three imbalanced USC load deviation datasets, the proposed method demonstrates superior performance on several key evaluation metrics, including Micro-F 1, Micro-G-mean , and Hamming Loss , with average values of 0.8497, 0.9150, and 0.1503, respectively. These results substantiate the effectiveness of the proposed method in accurately diagnosing the sources of load deviations in USC units.
作者机构：
[Zhang, Dou; Zhang, Yan; Liu, Lei] Cent South Univ, State Key Lab Powder Met, Changsha 410083, Peoples R China.;[Yuan, Xi] Cent South Univ, Coll Chem & Chem Engn, Changsha 410083, Peoples R China.;[Chen, Haiyan; Chen, HY; Jiang, Chengfeng] Changsha Univ Sci & Technol, Sch Energy & Power Engn, Key Lab Renewable Energy Elect Technol Hunan Prov, Changsha 410114, Peoples R China.
通讯机构：
[Chen, HY ; Zhang, D ] C;Cent South Univ, State Key Lab Powder Met, Changsha 410083, Peoples R China.;Changsha Univ Sci & Technol, Sch Energy & Power Engn, Key Lab Renewable Energy Elect Technol Hunan Prov, Changsha 410114, Peoples R China.
摘要：
HfO 2 -based ferroelectric films have been extensively explored and utilized in the field of non-volatile memory and electrical programmability. However, the trade-off between ferroelectric polarization and dielectric constant in HfO 2 has limited the overall performance improvement of devices in practical applications. Herein, a novel approach is proposed for the Hf 0.5 Zr 0.5 O 2 /ZrO 2 (HZO/ZrO 2 ) nanobilayer engineering, which can effectively regulate the phase structure evolution of HfO 2 films to construct a suitable morphotropic phase boundary (MPB). The findings highlight that the top ZrO 2 layer can regularly promote the formation of either the ferroelectric o-phase or the antiferroelectric t-phase. An ideal MPB is successfully established in HZO/ZrO 2 (6/9 nm) nanobilayer film by carefully optimizing the HZO/ZrO 2 thickness ratio, which presents a high dielectric constant of 52.7 and a large 2 P r value of up to 72.3 μC/cm 2 without any wake-up operation. Moreover, the HZO/ZrO 2 nanobilayer thin films demonstrate faster polarization switching speed (1.09 μs) and better fatigue performance (10 9 cycles) compared to the conventional HZO solid solution films. The relationship between ferroelectric and dielectric properties can be harmoniously balanced through the designation. The results indicate that the HZO/ZrO 2 nanobilayer engineering strategy is quite potential to pave the way for the development of next-generation memory technologies with superior performance and reliability.
HfO 2 -based ferroelectric films have been extensively explored and utilized in the field of non-volatile memory and electrical programmability. However, the trade-off between ferroelectric polarization and dielectric constant in HfO 2 has limited the overall performance improvement of devices in practical applications. Herein, a novel approach is proposed for the Hf 0.5 Zr 0.5 O 2 /ZrO 2 (HZO/ZrO 2 ) nanobilayer engineering, which can effectively regulate the phase structure evolution of HfO 2 films to construct a suitable morphotropic phase boundary (MPB). The findings highlight that the top ZrO 2 layer can regularly promote the formation of either the ferroelectric o-phase or the antiferroelectric t-phase. An ideal MPB is successfully established in HZO/ZrO 2 (6/9 nm) nanobilayer film by carefully optimizing the HZO/ZrO 2 thickness ratio, which presents a high dielectric constant of 52.7 and a large 2 P r value of up to 72.3 μC/cm 2 without any wake-up operation. Moreover, the HZO/ZrO 2 nanobilayer thin films demonstrate faster polarization switching speed (1.09 μs) and better fatigue performance (10 9 cycles) compared to the conventional HZO solid solution films. The relationship between ferroelectric and dielectric properties can be harmoniously balanced through the designation. The results indicate that the HZO/ZrO 2 nanobilayer engineering strategy is quite potential to pave the way for the development of next-generation memory technologies with superior performance and reliability.
