Article
Materials Science, Multidisciplinary
Qipeng Dong, Xiaming Chen, Hiromi Nagaumi, Xiaonan Wang, Bo Zhang
Summary: Dissimilar-filler welding often leads to macrosegregation, which degrades the performance of weld joints. This study reveals a new mechanism for the introduction of macrosegregation during dissimilar-filler welding, involving liquid segregation induced by dynamic heterogeneous mixing between the filler and base metal melts in the weld pool. In the front portion of the weld pool, heterogeneous mixing occurs uninhibitedly due to convection and continuous heat source, while in other regions, the reduced temperature of the weld pool results in solidification dominating heterogeneous mixing. Insufficient or partial heterogeneous mixing freezes the liquid segregation into the weld metal, introducing macrosegregation.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Engineering, Manufacturing
Xuejun Sun, Bojin Qi, Zihao Jiang, Caiyou Zeng, Baoqiang Cong
Summary: In this study, different current modes were used to butt-weld 1460 Al-Li alloy plates. The effects of these current modes on the weld microstructure and mechanical properties were compared. The results showed that modulating pulsed current can refine the grains in the weld zone and fusion zone, and significantly increase the quantity and width of a fine strip-like equiaxed grain zone. Both P-VPTIG and DP-VPTIG processes effectively enhanced the strength and elongation of the joints.
JOURNAL OF MANUFACTURING PROCESSES
(2022)
Article
Metallurgy & Metallurgical Engineering
E. Schulz, M. Wagner, H. Schubert, W. Zhang, B. Balasubramanian, L. N. Brewer
Summary: The development of short-pulse welding parameters for resistance spot welding of aluminum alloy AA6016-T4 using MFDC systems aimed to reduce heat input required for nugget formation. Optimization of current and time parameters is crucial for reducing energy requirements and avoiding weld imperfections, while simulations and experiments showed distinct weld nugget nucleation and growth phases.
Review
Materials Science, Multidisciplinary
Hao Chen, Zhengqiang Zhu, Yunming Zhu, Liang Sun, Yukun Guo
Summary: With the increasing demand for lightweight requirements, the welding preparation of Mg/Al composite structures is urgently needed and has extensive potential applications in the industrial field. However, welding Mg/Al dissimilar alloys often leads to the formation of brittle intermetallic compounds and difficulties in obtaining high-quality welded joints. Solid-state welding, characterized by low energy input and high efficiency, offers a solution to inhibit the formation of brittle intermetallic compounds and improve the strength of welded joints in Mg/Al dissimilar alloys. This paper summarizes and prospects the research status of solid-state welding using Mg/Al dissimilar alloys, focusing on the optimization of welding parameters, the addition of interlayers, and hybrid welding processes, based on recent literature on ultrasonic welding, friction welding, diffusion welding, explosive welding, magnetic pulse welding, and resistance spot welding of Al/Mg.
Article
Materials Science, Multidisciplinary
Narayanan Murali, Yitian Chi, Xiaochun Li
Summary: Nano-treatment shows great potential in enabling significant metallurgical capabilities in fusion welding dissimilar combinations of high-strength aluminum alloys, successfully addressing solidification defects and difficulties in heat treating, while promoting a significant natural aging response in the joint.
Article
Materials Science, Multidisciplinary
Akbar Heidarzadeh, Mousa Javidani, Mohammadreza Mofarrehi, Amir Farzaneh, X-Grant Chen
Summary: Underwater dissimilar friction stir welding of AA6061 and AA7075 aluminum alloys can improve the hardness performance of joints and exhibit different microstructural characteristics. Friction stir welding leads to a reduction in hardness values in all microstructural areas, but in underwater media, the hardness values in thermomechanically affected zones are higher compared to those reported in literature.
Article
Physics, Applied
Tomoki Harada, Daisuke Ohori, Kazuhiko Endo, Seiji Samukawa, Tetsuo Ikari, Atsuhiko Fukuyama
Summary: Thermal management is crucial for miniaturized semiconductor devices. In metal-oxide-semiconductor field-effect transistors, temperature rise due to heat generation can reduce electron mobility. By inserting nanostructures into the channel layer, temperature rise can be prevented and electron mobility can be maintained. The effect of nanostructure spacing on heat generation and carrier behavior of Si-NP/SiGe composite films was studied. The carrier lifetime was found to increase when the nanostructure spacing was comparable to the electron mean-free path.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Engineering, Mechanical
Anton Evdokimov, Nikolay Doynov, Ralf Ossenbrink, Aleksei Obrosov, Sabine Weiss, Vesselin Michailov
Summary: A numerical model was developed to compute distortions in laser-welded dissimilar overlap joints, considering properties of mixed steel-aluminum weld metal. Experimental results showed that the developed weld material model significantly improves the accuracy of thermomechanical simulations, with good agreement between computed and measured data.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
Article
Materials Science, Multidisciplinary
Chu Han, Ping Jiang, Shaoning Geng, Gaoyang Mi, Chunming Wang, Yuqiang Li
Summary: This study investigated the nucleation mechanisms of equiaxed grains in aluminum-lithium alloy welding joints during laser welding, revealing that grain detachment and heterogeneous nucleation are responsible for the formation of equiaxed grains. An improved method based on overlap welding procedure was proposed to clarify the nucleation mechanisms.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2021)
Article
Materials Science, Multidisciplinary
Shuwan Cui, Fuyuan Tian, Rong Ma, Yunhe Yu, Lei Xu
Summary: In this paper, the metal inert gas (MIG) welding process of 4 mm thick 6082-T6 aluminum alloy was simulated. The study investigates the evolution of microstructure, the strengthening mechanism of mechanical properties, and the corrosion characteristics of the welded joint. The results show that the welding heat input significantly influences the microstructure and mechanical properties, with an optimal heat input leading to improved strength and elongation. However, the corrosion resistance of the welded joint might be compromised under certain heat input conditions.
Article
Optics
Zhiyuan Jia, Peilei Zhang, Zhishui Yu, Haichuan Shi, Hongbing Liu, Di Wu, Xin Ye, Fuxin Wang, Yingtao Tian
Summary: Different pulse shaping designs can effectively improve the solidification condition of aluminum alloy pulsed laser welding spots, reducing the risk of solidification cracks.
OPTICS AND LASER TECHNOLOGY
(2021)
Article
Materials Science, Multidisciplinary
Yan Li, Dezhi Yang, Wenyu Yang, Zhisheng Wu, Cuirong Liu
Summary: Magnetic pulse welding (MPW) is a high-energy transient forming process widely used in the connection of dissimilar metals. This study focuses on the Al-Mg sheet welding process and uses numerical simulation to analyze the electromagnetic field and structural field characteristics to explain the forming mechanism of magnetic pulse welding.
Article
Nanoscience & Nanotechnology
Wentao Zhang, Jilin Xie, Yuhua Chen, Liping Zhang, Limeng Yin, Timing Zhang, Shanlin Wang
Summary: Magnetic pulse welding is used to join dissimilar metals Al/Ti, forming a gradient structure at the joint interface. The structure consists of amorphous, nano-scale, and ultrafine equiaxed grains, which are formed due to lattice collapse, super-diffusion, limited time and energy input, as well as dynamic recrystallization.
SCRIPTA MATERIALIA
(2022)
Article
Materials Science, Multidisciplinary
Cong Chen, Xuni Yin, Wei Liao, Yunzhong Xiang, Ming Gao, Yi Zhang
Summary: Increasing the laser scanning frequency and amplitude can improve the proportion of equiaxed grains and reduce the average diameter in the weld, leading to increased elongation. The scanning laser helps to enhance the strength of the weld fusion zone and provides a new way to improve the strength, safety, and service life of new energy power batteries through even distribution of elements and strengthening phases.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2021)
Article
Thermodynamics
Mustafa Umar, Sathiya Paulraj
Summary: The thermal characteristics of the weld pool during Yb:YAG laser welding of the AA5083-H111 aluminum alloy were studied using an infrared thermal imaging camera and a numerical model. Higher beam power led to an erratic molten pool and porosity formation. Porosities were mainly found in weldments processed with longer shielding gas blown distance due to insufficient gas pressure.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2021)
Article
Chemistry, Multidisciplinary
Wilhelm Pfleging, Petronela Gotcu
APPLIED SCIENCES-BASEL
(2019)
Article
Chemistry, Multidisciplinary
Penghui Zhu, Jiahao Han, Wilhelm Pfleging
Summary: In this study, aqueous processing of thick-film NMC 622 cathodes using carboxymethyl cellulose and fluorine acrylic hybrid latex as binders, with the addition of acetic acid to adjust slurry pH values, was investigated to improve traditional cathode manufacturing process.
Article
Chemistry, Multidisciplinary
Alexandra Meyer, Fabian Ball, Wilhelm Pfleging
Summary: In order to increase the specific capacity of anodes for lithium-ion cells, advanced active materials such as silicon were utilized in this study. Different types of silicon nanopowders were used to manufacture composite silicon/graphite electrodes, which showed promising performance with up to 200 full cycles achieved at 80% relative capacity. Impedance spectroscopies were conducted to correlate the silicon grade with SEI formation and charge transfer resistance values.
Article
Chemistry, Multidisciplinary
Yijing Zheng, Danni Yin, Hans Juergen Seifert, Wilhelm Pfleging
Summary: The application of the 3D battery concept on silicon-graphite electrodes shows a significant improvement in battery performances, including high-rate capability, cycle stability, and cell lifetime. The 3D architectures allow for volume expansion and additional lithium diffusion pathways, reducing degradation caused by volume change and enabling high-rate capability.
Article
Chemistry, Multidisciplinary
Zelai Song, Penghui Zhu, Wilhelm Pfleging, Jiyu Sun
Summary: The study investigated the influence of particle morphology on the performance of lithium-ion batteries by preparing cathodes with different particle sizes and conducting electrochemical characterization. The results showed that certain structures exhibited higher capacity, indicating the importance of morphology on battery performance.
Article
Chemistry, Physical
Juliana S. Solheid, Ahmed Elkaseer, Torsten Wunsch, Steffen Scholz, Hans J. Seifert, Wilhelm Pfleging
Summary: In this study, experiments and simulations were conducted to investigate the effects of parameters on the laser polishing of metal parts. Linear regression and artificial neural network models were developed based on the data obtained, and a multiobjective genetic algorithm optimization was applied to determine the optimal parameter combinations. The results showed that satisfactory surface quality and heat-affected zone depth could be achieved by selecting appropriate parameter values.
Article
Chemistry, Multidisciplinary
Lukas Schweighofer, Bernd Eschelmueller, Katja Froehlich, Wilhelm Pfleging, Franz Pichler
Summary: An electrochemical multi-scale model framework is proposed for simulating arbitrarily three-dimensional structured electrodes for lithium-ion batteries. The model is parameterized using laser ablation and fitted to four experimentally tested cells. The simulations are performed using finite element implementation in two and three dimensions. The virtually optimized cells can reduce prototyping costs and accelerate the production process.
Article
Chemistry, Multidisciplinary
Minh Xuan Tran, Peter Smyrek, Jihun Park, Wilhelm Pfleging, Joong Kee Lee
Summary: In this study, a three-dimensional structure for the cathode of tape-casting Ni-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) was prepared using femtosecond ultrafast-laser micro-patterning. The results showed that the 3D-NMC811 cathode exhibited higher capacity retention and rate capability compared to the 2D-NMC811 cathode, with faster Li+ ion transportation and lower charge-transfer resistance.
Article
Engineering, Manufacturing
Christoph Zwahr, Nicolas Serey, Lukas Nitschke, Christian Bischoff, Ulrich Raedel, Alexandra Meyer, Penghui Zhu, Wilhelm Pfleging
Summary: This article presents the application of Direct Laser Interference Patterning (DLIP) on current collector foils and highlights its potential advantages in increasing cycle lifetime and discharge capacity of lithium-ion batteries.
INTERNATIONAL JOURNAL OF EXTREME MANUFACTURING
(2023)
Article
Materials Science, Multidisciplinary
Alexandra Meyer, Yannic Sterzl, Wilhelm Pfleging
Summary: This research investigates the laser ablation processing of thick-film composite anodes using high repetition rates and provides detailed analysis of the pattern results. The findings are significant for electrode manufacturing in lithium-ion cells.
JOURNAL OF LASER APPLICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Ulrich Rist, Viktoria Falkowski, Wilhelm Pfleging
Summary: Laser-induced forward transfer (LIFT) technology was used to develop advanced electrode architectures and improve the electrochemical properties of batteries. The printing process was found to have no effect on the electrochemical performance of the battery materials. Multilayer electrodes with different particle types were printed and showed promising specific capacities. The LIFT technology provides the possibility for alternative electrode designs and optimization of 3D battery systems.
Article
Engineering, Biomedical
Eduardo Bock, Wilhelm Pfleging, Dayane Tada, Erenilda Macedo, Nathalia Premazzi, Rosa Sa, Juliana Solheid, Heino Besser, Aron Andrade
Summary: Laser treatment of titanium surfaces for ventricular assist devices is proposed in this study. The created biofunctional surface showed enhanced cell adhesion and proliferation in vitro, indicating its potential application in improving the performance of biomaterials for cardiac assistance devices.
Review
Engineering, Manufacturing
Wilhelm Pfleging
Summary: Traditional electrode manufacturing for lithium-ion batteries has reached high processing speeds and improvements in production costs, but new production concepts are needed for modern electric vehicles. Laser processing of battery materials is emerging as a promising tool to enhance battery performances. Promising developments in high-power, ultrafast laser technology may soon push laser structuring of batteries to the next technical readiness level.
INTERNATIONAL JOURNAL OF EXTREME MANUFACTURING
(2021)
Article
Chemistry, Physical
Matthias Stehle, Thomas L. Sheppard, Michael Thomann, Achim Fischer, Heino Besser, Wilhelm Pfleging, Jan-Dierk Grunwaldt
Summary: The study reveals the reaction progress and pathways at different positions in the reactor for the selective oxidation of propylene to acrolein, as well as the variations and conversion rates of products generated at different parts of the catalyst bed through spatially resolved activity and temperature measurements.
CATALYSIS SCIENCE & TECHNOLOGY
(2021)
Article
Chemistry, Physical
Juliana S. Solheid, Torsten Wunsch, Vanessa Trouillet, Simone Weigel, Tim Scharnweber, Hans Juergen Seifert, Wilhelm Pfleging
