233 results on '"Yunbo Zhong"'
Search Results
2. Graphene-decorated bimodal pure metal with high strength and ductility
- Author
-
Zhongze Lin, Zhe Sun, Boyi Luo, Ganpei Tang, Xin Jiang, Zhe Shen, Biao Ding, and Yunbo Zhong
- Subjects
bimodal structure ,graphene ,microstructure design ,mechanical properties ,microcrack behavior ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Heterostructured design and microcrack management mitigate the strength-ductility dilemma in metallic materials. Here, we demonstrate a simultaneous enhancement of strength and ductility in graphene-decorated bimodal pure nickel, achieving a strength increase to 1 GPa and an 18% improvement in elongation by designing heterostructure with graphene, metal powders, and metal foams. The results show that grain refinement, hetero-deformation-induced hardening, and activated stacking faults mainly cause the strength-ductility synergy. Additionally, while dispersed microcracks nucleate within the fine grain zones, their propagation is constrained by the coarse grain zones. This study provides new insights into improving the strength-ductility combination in metallic materials.
- Published
- 2024
- Full Text
- View/download PDF
3. The effect of alternative magnetic field on solidification structure improvement and primary carbide refinement in M50 ingots produced by vacuum arc remelting
- Author
-
Zhonghao Sun, Zhibin Xia, Mingliang Zhang, Yifeng Guo, Chengkuan Ma, Guodong Deng, Tianxiang Zheng, Zhe Shen, Biao Ding, Qiang Li, Chunmei Liu, and Yunbo Zhong
- Subjects
M50 bearing steel ,Primary carbide ,VAR ,Alternative magnetic field ,Mechanical properties ,Mining engineering. Metallurgy ,TN1-997 - Abstract
In the present study, the effect of the alternative magnetic field (AMF) on the metal pool shape, primary carbides formation, and mechanical properties during vacuum arc remelting (VAR) process was investigated by experiments and numerical simulations. Without AMF, the original depth of the molten pool was 87.74 mm. The application of the AMF decreased the depth of the metal pool, to various degrees (86.46 mm at 40 Gs 0.5 Hz, 78.96 mm at 40 Gs 0.1 Hz, 69.82 mm at 40 Gs 0.05 Hz). As a consequence, the primary carbides became more refined average size reduced by 20.66%∼25.72%. After modification, uniformly distributed hardness and improved wear resistance was achieved. Meanwhile, compared with 0.5 and 0.1 Hz cases, the strengthening effect was more obvious at 0.05 Hz. The numerical simulation results showed that, the AMF and the melting current in the molten steel produced Lorentz force, which caused the horizontal circulation. Therefore, the temperature of metal pool became more homogenized under the horizontal circulation. When the frequency was 0.05 Hz, the horizontal circulation in liquid steel was more intense, which makes the temperature field more uniform. Horizontal circulation can also reduce the segregation of alloying elements, which restrains the precipitation condition and refines primary carbides. The hardness uniformity can also be attributed to the uniform distribution of alloying elements. The improvement in wear resistance is attributed to the refinement of the primary carbide, thereby reducing the occurrence of primary carbide spalling during friction.
- Published
- 2024
- Full Text
- View/download PDF
4. Effects of microalloying and magnetic annealing on microstructures and properties of magnetic immiscible copper matrix alloys
- Author
-
Tianxiang Zheng, Sulin Chen, Hao Li, Ziyang Chen, Wenhao Lin, Hao Cai, Bangfei Zhou, Chunmei Liu, Yunbo Zhong, and Qiuliang Wang
- Subjects
Immiscible Cu–Fe alloys ,Static magnetic field ,Annealing ,Precipitations ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The magnetic immiscible copper matrix alloys are extensively industrial applications due to their comprehensive properties such as high strength, high conductivity, high thermal conductivity and excellent magnetic permeability. Here, we investigated the effects of the addition of Co and Al elements on the microstructural evolution of magnetic Cu–Fe alloys (CFAs) and comprehensive properties after annealing under the static magnetic field (SMF). The results show that the microalloying was effective in enhancing the mechanical and magnetic properties but negative for the electric conductivity. The addition of Co element significantly suppressed the grains recrystallization of CFAs during the annealing process and improved the thermal stability of CFAs. Al elements homogeneously dispersed in the sample. SMF facilitated the nucleation and precipitation processes of the secondary precipitated particles in the Cu-rich matrix through the introducing the extra magnetic Gibbs free energy and also promoted the structural transformation of the secondary precipitated particles from FCC to BCC. This work indicates that SMF can be effectively used to modify the magnetic materials with exceptional comprehensive properties during the solid state phase transformation process. It also provides valuable guidance for the development of novel materials with superior comprehensive performance.
- Published
- 2024
- Full Text
- View/download PDF
5. High strength and excellent softening resistance Cu–15Ni–8Sn alloy by Ti addition
- Author
-
Liangguo Chen, Yuanxin Liang, Boyi Luo, Biao Ding, Zhe Shen, Shunran zhang, Haibiao Lu, Tianxiang Zheng, Qiang Li, Bangfei Zhou, Chunmei Liu, Weili Ren, and Yunbo Zhong
- Subjects
Cu-15Ni–8Sn alloy ,Ti microalloying ,Softening resistance ,Discontinuous precipitation ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Cu–15Ni–8Sn alloy is commonly utilized in various applications because of its exceptional strength, elasticity, and softening resistance. Ti microalloying has been employed to enhance the mechanical properties of Cu–15Ni–8Sn alloy. By adding 0.5 wt% Ti, the peak-ageing tensile strength, microhardness, and elastic modulus of the Cu–15Ni–8Sn alloys reach 1401.3 MPa, 479.3 Hv, and 154.7 GPa, respectively, representing the greatest comprehensive performance reported in previous literature. Additionally, the Ti microalloying significantly enhances the softening resistance of Cu–15Ni–8Sn alloys. After ageing at 400 °C for 10 h, the tensile strength of the Cu–15Ni–8Sn-0.5Ti alloy decreases by only around 150 MPa, whereas the alloy without Ti addition experiences a decrease close to 350 MPa. Quantitative analysis reveals that the observed improvements can be attributed to the Ti microalloying inhibiting the dislocation annihilation and the formation of discontinuous precipitation during the ageing process, while simultaneously promoting the precipitation of Ni3Ti. This study provides a theoretical basis for preparing a high-performance Cu–15Ni–8Sn alloy by microalloying.
- Published
- 2024
- Full Text
- View/download PDF
6. Optimization of grain-selection behavior in the spiral selector during Cusp-magnetic-field-assisted directional solidification of single-crystal superalloy
- Author
-
Congjiang Zhang, Xingjin Hu, Xiaotan Yuan, Weili Ren, Haibiao Lu, Biao Ding, Qiang Li, Tianxiang Zheng, Zuosheng Lei, Yunbo Zhong, Ang Zhang, and Peter K. Liaw
- Subjects
Single-crystal superalloy ,Grain selection ,Spiral selector ,Cusp magnetic field ,Directional solidification ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Cusp magnetic field (CMF) could overcome the damage of the longitudinal or transverse magnetic fields on the directional growth of dendrites in single crystal (SC) superalloy, which shows the promising prospects in the industrial application. The SC preparation is obtained by the spiral selector in industry. Thus, the work investigates the effect of CMF on the grain selection of SC superalloy with starter-block heights and temperature gradients in the spiral selector for the first time. The results show that the favorable effect of CMF on SC selection in the spiral selector is all related with the starter-block heights at the temperature gradients. At the high starter-block height, the CMF decreases the height of the selected SC in the spiral section and optimizes the selected orientation. The less grains in the entrance make the favorable effect of CMF on SC selection be realized in the spiral section. The CMF effect on SC selection in the spiral selector origins from the change of the flow field structure near the liquid-solid interface. It not only enhances the effect of grain competition and selection in the high starter block but also makes the liquid-solid interface less tilt for favorably competition growth of dendrites in the spiral channel. The investigation provides a new means and a theory instruction for optimizing the SC selection in the spiral selector.
- Published
- 2024
- Full Text
- View/download PDF
7. Synergistic control of microstructures and properties in eutectic high-entropy alloys via directional solidification and strong magnetic field
- Author
-
Xin Jiang, Yi Li, Peijian Shi, Yinpan Yang, Mingyang Wang, Jingran Huang, Yi Qin, Yifan Lin, Bodong Tan, Yiheng Ruan, Xiaohan Wang, Bangfei Zhou, Biao Ding, Qiang Li, Zhe Shen, Tianxiang Zheng, Chunmei Liu, Peter K. Liaw, and Yunbo Zhong
- Subjects
Eutectic high-entropy alloy ,Directional solidification ,Strong magnetic field ,Microstructures ,Tensile properties ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The AlCoCrFeNi2.1 eutectic high-entropy alloy (Ni2.1 EHEA), as an exemplary representative of the high-entropy alloy family, has garnered significant research attention owing to its exceptional comprehensive properties. In this study, we investigated the influence of various growth velocities on the microstructure, lamellar spacing, and mechanical properties of the Ni2.1 EHEA. We observed that at lower growth velocities, the structure consisted of an alternating face-centered-cubic (FCC) phase and B2 phase lamellae aligned in a single direction, with the lamellae orientation parallel to the direction of the heat flow. The yield strength increased with the growth rate, while the ultimate tensile strength decreased with increasing the growth velocity. Ductility remained relatively consistent, and a double yield phenomenon was observed in the elastic-plastic deformation region. Under conditions of high growth velocities, the microstructure transitioned from a single-directional full lamellar structure to a multi-stage lamellar arrangement. The most favorable comprehensive mechanical properties were achieved at a growth rate of 200 μm/s, resulting in a yield strength of 450 MPa, an ultimate tensile strength of 1092 MPa, and a remarkable ductility of ∼32% in the directionally solidified samples—double that of the arc-melted sample. The evolution law of directional solidification structures under the coupling effect of different magnetic fields and different growth rates was studied. The interaction of the thermoelectric-magnetic force and thermoelectric-magnetic convection and the potential mechanism of microstructure evolution under the effect of magnetic field were deeply analyzed. The results reveal that at a growth rate of 2 μm/s, the spacing between eutectic layers decreases as the magnetic induction intensity increases, leading to the transformation of some regular layers into spherical layers. Similarly, at a growth velocity of 10 μm/s, the eutectic structure exhibited a Columnar-to-equiaxed transition (CET). However, as the growth rate further increases, the limited exposure time to the magnetic field prevented significant structural changes.
- Published
- 2024
- Full Text
- View/download PDF
8. Study on the homogeneity of tilted dendritic structures in single crystal superalloys
- Author
-
Xiaotan Yuan, Congjiang Zhang, Hongbin Yu, Weili Ren, Biao Ding, Haibiao Lu, Yunbo Zhong, Zuosheng Lei, Hui Wang, Qiuliang Wang, Peter K. Liaw, Xuezhi Qin, and Lanzhang Zhou
- Subjects
Dendritic array ,Stacking structure ,Local primary spacing ,Phase-field simulation ,Solute distribution ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Dendrites play a crucial role in the microstructure of single crystal superalloys, predominantly developing along the [001] orientation. The mechanical performance is greatly influenced by the uniform distribution of dendrites. During the solidification process, we frequently observe instances of dendrites deviating from the [001] orientation, resulting in tilted structures. These deviations give rise to both aligned and misaligned arrays within the transverse section. The study comprehensively examines the homogeneity of tilted dendritic structures. As solidification progresses, new dendrites within the aligned array tend to maintain a hexagonal structure. Simultaneously, the remaining metastable structures gradually transition into hexagonal structures. In contrast, various polygons mutually transform in misaligned array, resulting in a dynamic adjustment of their proportions. Consequently, the aligned array exhibits a higher proportion of hexagonal structures and a more uniform dendrite spacing compared to the misaligned array. Within the transitional region, an increase in heptagonal structures leads to heightened non-uniformity in dendrite spacing. The predominance of hexagonal structures can be attributed to their more uniform solute distribution, facilitated by the characteristics of the aligned array, which promote hexagonal structure formation by adjusting the solute field distribution. On the other hand, due to the random positioning of dendrites in the misaligned array, various stacking structures coexist in dynamic equilibrium. The research reveals an intrinsic relationship between macroscopic array patterns, stacking structures, dendrite spacing, and microscopic solute distribution. These findings provide a theoretical foundation for the production of high-quality single crystal dendritic structures and offer insights into their influence on material properties.
- Published
- 2023
- Full Text
- View/download PDF
9. Cleanliness improvement and microstructure refinement of H13 die steel by laboratory magnetic-controlled electroslag remelting
- Author
-
Chengkuan Ma, Guodong Deng, Zhonghao Sun, Tianxiang Zheng, Zhe Shen, Biao Ding, Chunmei Liu, Yifeng Guo, Qiang Li, and Yunbo Zhong
- Subjects
Cleanliness ,Microstructure ,Magnetic-controlled electroslag remelting ,H13 die steel ,Transverse static magnetic field ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The current work investigated the impact of transverse static magnetic field (TSMF) with varied magnetic flux density (MFD) on cleanliness and microstructure of laboratory scale electroslag remelted H13 die steel. The inclusion morphology and microstructure evolution of electroslag remelted ingots were examined utilizing scanning electron and optical microscopes, respectively. The number and size of inclusions in ingots were detected using the FEI Aspex Explorer. The results demonstrated that the number/size of inclusions in H13 electroslag remelted ingots were decreased as the MFD of applied TSMF increased. This resulted from the application of the TSMF, which produced the thinner liquid melting film (LMF), smaller droplets, and shallower metal molten pool, strengthening the kinetic conditions for inclusion migration to the slag-metal interface and the removal process. When the MFD of the applied TSMF was higher (95 mT and 140 mT), the LMF became thinner, the droplets became smaller, and the metal pool became shallower were more visible. Moreover, the metal pool became shallower and the local solidification time became shorter after applying TSMF with larger MFD, resulting in finer dendritic structure and carbides.
- Published
- 2023
- Full Text
- View/download PDF
10. Unveiling microstructural origins of the balanced strength–ductility combination in eutectic high-entropy alloys at cryogenic temperatures
- Author
-
Yi Li, Peijian Shi, Mingyang Wang, Yinpan Yang, Yan Wang, Yiqi Li, Yuebo Wen, Weili Ren, Na Min, Yan Chen, Yifeng Guo, Zhe Shen, Tianxiang Zheng, Ningning Liang, Wenjun Lu, Peter K. Liaw, Yunbo Zhong, and Yuntian Zhu
- Subjects
Eutectic high-entropy alloys ,mechanical properties ,multi-slip scenario ,compatible co-deformation ,HDI hardening ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Eutectic high-entropy alloys (EHEAs) feature attractive strength–ductility balance at both ambient and cryogenic temperatures. Nevertheless, microstructural origins underpinning these balanced mechanical properties remain elusive. Here the deformation mechanisms of a recently-reported Al19Co20Fe20Ni41 EHEA were comparatively investigated at 298 and 77 K, which revealed a high frequency and density of dislocation multi-slip scenario in the soft eutectic lamellae and the corresponding compatible co-deformation in the adjacent hard lamellae that collectively endowed strong hetero-deformation-induced (HDI) hardening and excellent forest-dislocation hardening. Therefore, better ductility and tensile strength, in comparison to the other widely-studied EHEA system, could be sustained even at liquid-nitrogen temperatures.
- Published
- 2022
- Full Text
- View/download PDF
11. Numerical Simulation of Flow and Argon Bubble Distribution in a Continuous Casting Slab Mold under Different Argon Injection Modes
- Author
-
Zexian He, Qiao Cheng, Haibiao Lu, Yunbo Zhong, Changgui Cheng, Jingxin Song, and Zuosheng Lei
- Subjects
continuous casting ,argon injection mode ,numerical simulation ,bubble size distribution ,population balance model ,Mining engineering. Metallurgy ,TN1-997 - Abstract
A three-dimensional model is established to investigate the effect of argon injection mode, argon flow rate and casting speed on the gas–liquid two-phase flow behavior inside a slab continuous casting mold. The Eulerian–Eulerian model is employed to simulate the gas–liquid flow, and the population balance model is applied to describe the bubble breakage and coalescence process in the mold. The numerical simulation results of the bubble size distribution are verified using the water model experiment. The results show that the flow field and bubble distribution are similar between the argon injection at the upper submerged entry nozzle (SEN) and tundish upper nozzle (TUN), while the number density is larger for the argon injection of TUN. The coalescence rate of bubbles and the bubble size inside the mold increase with increasing argon flow rate. When the argon flow rate exceeds 4 L/min, the flow pattern of liquid steel changes from double-roll flow to complex flow, with aggravation of the level fluctuation of the top surface near the SEN. When the casting speed increases, the bubble breakup rate increases and results in a decrease in the size of bubbles inside the mold. At a high casting speed, the flow pattern tends to form double-roll flow, and the liquid level at the narrow face of the top surface increases.
- Published
- 2023
- Full Text
- View/download PDF
12. Saturation effect of creep-fatigue cyclic-life for Nickel-based superalloy DZ445 under long-term tensile dwell periods at 900 °C
- Author
-
Shunran Zhang, Weili Ren, Biao Ding, Yunbo Zhong, Xiaotan Yuan, Tianxiang Zheng, Zhe Shen, Yifeng Guo, Qiang Li, Chunmei Liu, Jianchao Peng, Josip Brnic, Yanfei Gao, and Peter K. Liaw
- Subjects
Creep-fatigue ,Saturation of cyclic life ,Long-term dwell time ,Mechanical response ,Damage mechanism ,Mining engineering. Metallurgy ,TN1-997 - Abstract
This investigation determined the creep-fatigue cyclic-life (Nf) saturation effect for the DZ445 superalloy with 16–128 min dwell time at 900 °C and total strain range of 1.6%. When the dwell time exceeds 8 min, the mechanical response including maximum stress response, hysteresis loop, plastic strain range, and stress relaxation amount at characteristic cycle are also saturated with dwell time gradually. The Nf saturation effect is also reflected in the creep- and ductile-dominated fracture modes. This critical phenomenon is closely related to the dynamic equilibrium reached between the superdislocations of a/2[101] in γˊ precipitation and the formation of the dislocation networks. While the rupture time is increased continuously with dwell time, which could be better used as an evaluation index when the cyclic life is saturated. The Nf saturation effect can not only reduce the cost of tests with long-dwell time, but also provide the guidance for creep-fatigue safety design.
- Published
- 2022
- Full Text
- View/download PDF
13. Carbides refinement and mechanical properties improvement of H13 die steel by magnetic-controlled electroslag remelting
- Author
-
Chengkuan Ma, Zhibin Xia, Yifeng Guo, Weifeng Liu, Xuhui Zhao, Qiang Li, Wentao Qi, and Yunbo Zhong
- Subjects
Carbides ,MC-ESR ,Mechanical properties ,H13 die steel ,Axial static magnetic field ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The effect of an axial static magnetic field (ASMF) on the carbides and mechanical properties of electroslag remelted H13 die steel was studied in current work. Optical microscope (OM) and scanning electron microscope (SEM) were used to analyze the solidification structure and carbide morphology of electroslag remelting (ESR) ingots. The FEI Aspex Explorer was utilized to detect the inclusions in H13 ESR ingots. Compared with conventional ESR, the application of ASMF in this study made the metal molten pool shallower and flatter, resulting in shorter local solidification time and uniform distribution of solute atoms, which alleviated the element segregation degree, and further inhibited the formation of primary carbides. The magnetic-controlled electroslag remelting (MC-ESR) process not only refined the dendrite structure (tended to grow parallel to the ingot axis) and the carbides, but also improved the inclusion removal efficiency and mechanical properties of H13 ESR ingots.
- Published
- 2022
- Full Text
- View/download PDF
14. Quality Prediction of Continuous Casting Slabs Based on Weighted Extreme Learning Machine
- Author
-
Yuhan Liu, Haibiao Lu, Huiqi Zhang, Xing Wu, Yunbo Zhong, and Zuosheng Lei
- Subjects
Quality prediction ,weighted extreme learning machine ,continuous casting ,class imbalance ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
A slab quality prediction model based on machine learning plays an important role in improving final slab quality. However, the class imbalance of continuous casting datasets has a negative impact on the training of basic machine-learning models. In this study, weighted extreme learning machine (WELM) models are constructed to predict the slab quality of under different operation patterns by feeding millions of data. The results show that WELM models can achieve better prediction performance on the two types of continuous casting datasets than the basic algorithms. The superiority of WELM is demonstrated by the relatively high-precision identification of every kind of slab. The performance of WELM models with different weighting schemes is studied and the model with the golden section ratio weighting method is recommended for application as a quality prediction model. Meanwhile, WELM can still maintain a good predictive performance and generalization ability when training a large amount of data. This model can satisfy the demands for slab quality prediction and optimize the continuous casting process.
- Published
- 2022
- Full Text
- View/download PDF
15. Morphology tailoring of metal pool and eutectic carbides in magnetic-controlled electroslag remelted M2 high-speed steel
- Author
-
Yifeng Guo, Wentao Qi, Zhibin Xia, Xuhui Zhao, Qiang Li, Chunmei Liu, Biao Ding, Zhe Shen, Tianxiang Zheng, and Yunbo Zhong
- Subjects
MC-ESR ,TSMF ,M2 HSS ,Metal pool ,Eutectic carbides ,Electromagnetic excitation ,Mining engineering. Metallurgy ,TN1-997 - Abstract
A transverse static magnetic field (TSMF) was superimposed during electroslag remelting (ESR) process to regulate the shape of metal pool, the eutectic carbides morphology as well as the mechanical properties of electroslag remelted M2 high-speed steel (HSS) in current study. The metal pool became shallower and flatter after applying a 65 mT TSMF. Moreover, refined eutectic carbides and solidification structure (tended to grow axial) of the ESR ingot were obtained, together with uniform/improved mechanical properties (hardness, wear). Modifications of the morphology of metal pool and grain growth angle under the TSMF were attributed to a periodic electromagnetic excitation effect on droplets transition characteristics, which changed the drop path of the droplets (single to multiple drop) and homogenized the temperature distribution in metal pool. In addition, local solidification time (LST) became shorter and the number of inclusions ((Ti, V)N–Al2O3 and (Ti, V)N) which acted as heterogeneous nuclei for eutectic carbides formation increased (the inclusions also became finer) due to TSMF, resulting in the refinement of the eutectic carbides in ESR ingots.
- Published
- 2022
- Full Text
- View/download PDF
16. High‐Performance Semitransparent Organic Solar Cells: From Competing Indexes of Transparency and Efficiency Perspectives
- Author
-
Tao Xu, Yiran Luo, Shiwei Wu, Baozhong Deng, Shi Chen, Yunbo Zhong, Shenghao Wang, Gaëtan Lévêque, Renaud Bachelot, and Furong Zhu
- Subjects
bilayer dielectric optical coupling layer ,gold nanobipyramids ,near‐infrared ,plasmonic effect ,semitransparent organic solar cells ,Science - Abstract
Abstract Semitransparent organic solar cells (ST‐OSCs) offer potentially more opportunities in areas of self‐powered greenhouses and building‐integrated photovoltaic systems. In this work, the effort to use a combination of solution‐processable gold nanobipyramids (AuNBPs)‐based hole transporting layer and a low/high dielectric constant double layer optical coupling layer (OCL) for improving the performance of ST‐OSCs over the two competing indexes of power conversion efficiency (PCE) and average visible transmittance (AVT) is reported. The fabrication and characterization of the ST‐OSCs are guided, at design and analyses level, using the theoretical simulation and experimental optimization. The use of a low/high dielectric constant double layer OCL helps enhancing the visible light transparency while reflecting the near‐infrared (NIR) photons back into the photoactive layer for light harvesting. NIR absorption enhancement in the ST‐OSCs is realized through the AuNBPs‐induced localized surface plasmon resonance (LSPR). The weight ratio of the polymer donor to nonfullerene acceptor in the bulk heterojunction is adjusted to realize the maximum NIR absorption enhancement, enabled by the AuNBPs‐induced LSPR, achieving the high‐performance ST‐OSCs with a high PCE of 13.15% and a high AVT of 25.9%.
- Published
- 2022
- Full Text
- View/download PDF
17. Review on Eutectic-Type Alloys Solidified under Static Magnetic Field
- Author
-
Hao Cai, Wenhao Lin, Meilong Feng, Tianxiang Zheng, Bangfei Zhou, and Yunbo Zhong
- Subjects
static magnetic field ,eutectic-type alloys ,solidification ,review ,Crystallography ,QD901-999 - Abstract
Processing metallic alloys under a static magnetic field (SMF) has garnered significant attention over the past few decades. SMFs can influence both the thermodynamics and kinetics of the solidification process by introducing extra force and energy. Eutectic-type alloys (ETAs) are commonly used as research materials under SMFs due to their featured microstructures. This review aims to present theoretical and experimental results regarding ETAs under SMFs, from post-analysis to in situ observation, to demonstrate the effects of magnetic phenomena such as magnetic braking, thermoelectric magnetic convection, magnetic gradient force, and magnetic energy on the thermodynamics and kinetics of microstructural evolution. In this paper, we adopt a hybrid approach between a review and an overview to comprehensively examine the effect of SMFs on the solidification process. Firstly, we provided a concise review of the historical research on the SMF’s impact on solidification in the literature. Next, we elucidated the basic physical principles of an SMF in material processing, followed by an introduction of numerous laboratory and industrial experiments that have utilized SMFs. Finally, we summarized the effects of SMFs on solidification in the past and provide insights into future research directions.
- Published
- 2023
- Full Text
- View/download PDF
18. Morphology Control of Metal Pool and Eutectic Carbides in Electroslag Remelted M2 HSS with an External Axial Static Magnetic Field
- Author
-
Xuhui Zhao, Zhonghao Sun, Zhibin Xia, Chunmei Liu, Zhe Shen, Biao Ding, Tianxiang Zheng, Yifeng Guo, Qiang Li, and Yunbo Zhong
- Subjects
M2 HSS ,ESR ,ASMF ,metal pool ,ECs ,Mining engineering. Metallurgy ,TN1-997 - Abstract
This study investigates the influence of a superimposed axial static magnetic field (ASMF) on the morphology of metal pool and eutectic carbides (ECs) in electroslag remelted M2 high-speed steel (HSS). The application of ASMF caused the metal pool to become shallower, and the solidified structure to expand axially, along with finer (i.e., more uniformly distributed and crystallographically oriented) ECs. Lorentz force-driven unidirectional circulation in slag pool was the primary cause of the metal pool’s morphological adjustment; this resulted in a more homogenous temperature distribution in slag pool. Thus, the heat transfer from the slag pool to the metal pool became more uniform, creating a metal pool that is shallower. Additionally, local solidification time (LST) became shorter, while the number of (Ti, V)N-Al2O3 inclusions serving as heterogeneous nuclei for EC formation increased due to ASMF, enabling finer EC with more crystallographic orientations in ESR ingots.
- Published
- 2023
- Full Text
- View/download PDF
19. Enhanced strength–ductility synergy in ultrafine-grained eutectic high-entropy alloys by inheriting microstructural lamellae
- Author
-
Peijian Shi, Weili Ren, Tianxiang Zheng, Zhongming Ren, Xueling Hou, Jianchao Peng, Pengfei Hu, Yanfei Gao, Yunbo Zhong, and Peter K. Liaw
- Subjects
Science - Abstract
Producing in situ composite materials with superior strength and ductility has long been a challenge. Here, the authors use lamellar microstructure inherited from casting, rolling, and annealing to produce an ultrafine duplex eutectic high entropy alloy with outstanding properties.
- Published
- 2019
- Full Text
- View/download PDF
20. Effect of Vertical High Magnetic Field on the Morphology of Solid-Liquid Interface during the Directional Solidification of Zn-2wt.%Bi Immiscible Alloy
- Author
-
Bangfei Zhou, Xianghui Guo, Wenhao Lin, Ying Liu, Yifeng Guo, Tianxiang Zheng, Yunbo Zhong, Hui Wang, and Qiuliang Wang
- Subjects
high magnetic field ,immiscible alloy ,solid-liquid interface ,constitutional supercooling ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The morphology of the solid-liquid (S-L) interface is crucial for the directionally solidified microstructures of various alloys. This paper investigates the effect of vertical high magnetic field (VHMF) on the morphology evolution of the S-L interface and the solidified microstructure during the directional solidification of Zn-2wt.%Bi immiscible alloy. The results indicate that the morphology of the S-L interface is highly dependent on the VHMF, resulting in various solidified microstructures. When the growth rate was 1 μm/s, the aligned droplets were formed directly at the disturbed S-L interface under a 1 T VHMF. However, the stability of the S-L interface was improved to form a stable Bi-rich fiber under a 5 T VHMF. When the growth rate was 5 μm/s, the S-L interface was changed from cellular to dendritic to cellular again with increasing magnetic flux density. A theory regarding constitutional supercooling and efficient solute diffusion has been proposed to explain the S-L interface transition under the VHMF. The difference in the effective diffusion capacity of the solute originates from the thermoelectric magnetic effect and the magneto-hydrodynamic damping effect. The present work may initiate a new method to transform the solidified microstructures of immiscible alloys via an applied magnetic field during directional solidification.
- Published
- 2022
- Full Text
- View/download PDF
21. Diffusion-controlled mechanical property-enhancement of Al-20wt.%Si ribbon annealed under high static magnetic fields, from the microscale to the atomic scale
- Author
-
Tianxiang Zheng, Peijian Shi, Zhe Shen, Bangfei Zhou, Wenhao Lin, Xue Liang, Wenqing Liu, Xu Chen, Yunbo Zhong, Hui Wang, and Qiuliang Wang
- Subjects
Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Al-20wt.%Si hypereutectic alloys were designed in order to study how a high static magnetic field (HSMF) during annealing affected the microstructure evolution, atomic diffusion, and resultant mechanical properties from the microscale to the atomic scale. Our results indicate that the size of the primary silicon particles (PSPs) increased with increasing temperature, while it decreased with increasing magnetic flux density (MFD). The solid solubilities of the Al matrix were 0.84 wt% and 0.53 wt% for the ribbons annealed at 0 T and 8 T, respectively. HSMF decreased the precipitation rate of Al from the PSPs and retained the solute trapping effect in the PSPs during annealing. After annealing the ribbon, the Al matrix retained the lattice distortions under the HSMF. Applying a HSMF led to the coexistence of grain boundary strengthening, particle strengthening, dislocation strengthening, and solid solution strengthening, so the hardness and elastic modulus increased with increasing MFD. Compared with the ribbon annealed at 8 T, the ribbon annealed at 0 T had a hardness and elastic modulus improved by 139.47% and 1053.2%, respectively. This paper presents a new way to design heat treatments and even solidification processes for metallic materials by controlling their diffusion by applying an HSMF. Keywords: Melt spinning, Annealing, High static magnetic field, Nanoindentation, Coarsening, Diffusion
- Published
- 2020
- Full Text
- View/download PDF
22. Field-induced tricritical phenomenon and magnetic structures in magnetic Weyl semimetal candidate NdAlGe
- Author
-
Jun Zhao, Wei Liu, Azizur Rahman, Fanying Meng, Langsheng Ling, Chuanying Xi, Wei Tong, Yuming Bai, Zhaoming Tian, Yunbo Zhong, Ying Hu, Li Pi, Lei Zhang, and Yuheng Zhang
- Subjects
critical phenomenon ,anisotropy ,critical exponent ,scaling ,phase diagram ,Science ,Physics ,QC1-999 - Abstract
Non-centrosymmetric NdAlGe is considered to be a candidate for magnetic Weyl semimetal in which the Weyl nodes can be moved by magnetization. Clarification of the magnetic structures and couplings in this system is thus crucial to understand its magnetic topological properties. In this work, we conduct a systematical study of magnetic properties and critical behaviors of single-crystal NdAlGe. Angle-dependent magnetization exhibits strong magnetic anisotropy along the c -axis and absolute isotropy in the ab -plane. The study of critical behavior with H ∥ c gives critical exponents β = 0.236(2), γ = 0.920(1), and δ = 4.966(1) at critical temperature T _C = 5.2(2) K. Under the framework of the universality principle, M ( T , H ) curves are scaled into universality curves using these critical exponents, demonstrating reliability and self-consistency of the obtained exponents. The critical exponents of NdAlGe are close to the theoretical prediction of a tricritical mean-field model, indicating a field-induced tricritical behavior. Based on the scaling analysis, a H – T phase diagram for NdAlGe with H ∥ c is constructed, revealing a ground state with an up-up-down spin configuration. The phase diagram unveils multiple phases including up-up-down domains, up-up-down ordering state, polarized ferromagnetic (PFM), and paramagnetic (PM) phases, with a tricritical point (TCP) located at the intersection [ T _TCP = 5.27(1) K, H _TCP = 30.1(3) kOe] of up-up-down, PFM, and PM phases. The multiple phases and magnetic structures imply a delicate competition and balance between variable interactions and couplings, laying a solid foundation for unveiling topological properties and critical phenomena in this system.
- Published
- 2022
- Full Text
- View/download PDF
23. Numerical Simulation on Saffman Force Controlled Inclusions Removal during the ESR Process
- Author
-
Chuxiong Sun, Yifeng Guo, Qiang Li, Zhe Shen, Tianxiang Zheng, Huai Wang, Weili Ren, Zuosheng Lei, and Yunbo Zhong
- Subjects
electroslag remelting ,Saffman force ,fluid flow ,inclusion removal ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Electroslag remelting (ESR) is an effective method for removing nonmetallic inclusions from steels or alloys. The main stage of inclusion removal during ESR is the aggregation of liquid metal film (LMF) to form droplets at the consumable electrode tip. In this study, a lab-level ESR experiment was carried out. The number and size of inclusions at the characteristic position of the electrode were quantitatively counted. The number of inclusions in the center position of LMF were larger than that in other regions. To elucidate these phenomena, a two-dimensional mathematical model was established to study the migration of inclusions in LMF. The results indicate that due to the large velocity gradient in LMF, the Saffman force is strong enough to offset the buoyant force and drag the inclusions toward the slag/LMF interface (SFI), where the inclusions will be dissolved in the SFI region by the molten slag. This study demonstrates that the Saffman force plays a key role in the removal of nonmetallic inclusions in LMF during the ESR process.
- Published
- 2020
- Full Text
- View/download PDF
24. A new single crystal high entropy alloy with excellent high-temperature tensile property
- Author
-
Huaqiang Chen, Xiaotan Yuan, Weili Ren, Jianchao Peng, Biao Ding, Tianxiang Zheng, Jianbo Yu, Peter K Liaw, and Yunbo Zhong
- Subjects
high entropy alloy ,tensile behavior ,high temperature properties ,high strength ,Materials of engineering and construction. Mechanics of materials ,TA401-492 ,Chemical technology ,TP1-1185 - Abstract
A new single crystal high entropy alloy is developed and produced using Bridgman directional-solidification and seed-crystal method. The microstructure exhibits the directional dendrite morphology and is mainly composed of the FCC matrix and the L1 _2 ordered precipitates. Its high-temperature yield strengths are far higher than those of the first-generation single crystal superalloys, and close to those of the second- generation ones. The solid-solution strengthening effect from the high content of W and Mo, as well as the precipitation strengthening effect from the combined addition of Al, Ti, Ta, and Nb, should be responsible for the excellent high-temperature strength of the investigated alloy.
- Published
- 2020
- Full Text
- View/download PDF
25. Steel/Slag Interface Behavior under Multifunction Electromagnetic Driving in a Continuous Casting Slab Mold
- Author
-
Xiaohui Sun, Bin Li, Haibiao Lu, Yunbo Zhong, Zhongming Ren, and Zuosheng Lei
- Subjects
multifunction electromagnetic driving ,steel/slag interface ,continuous casting ,slab mold ,electromagnetic stirring ,electromagnetic braking ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The transient numerical model combined with the volume of fluid (VOF) approach is employed to investigate the steel/slag interface behavior under multifunction electromagnetic driving in a continuous casting slab mold. Here, electromagnetic stirring (EMS) and electromagnetic braking (EMBr), respectively, are chosen as flow multifunction control technologies in the upper and lower areas of the mold. The computational models are validated with measurement results. The results show that multifunction electromagnetic driving changes the flow pattern, which has the potential to simultaneously meet the requirements of the steel flow in the regions above and below the nozzle, ensuring the uniformity and activity of the molten steel in the upper region of the mold and avoiding the excessive depth of the impinging jet. After EMS, the steel forms a deflected circulation flow at the steel/slag interface, and the surface velocity distribution is more uniform. EMBr still has the function of stabilizing the meniscus when multifunction electromagnetic driving is applied. Taking wave height and wave amplitude as evaluation criteria, the influence of EMS and EMBr on the steel/slag interface can be evaluated and controlled to some extent by observing the key points.
- Published
- 2019
- Full Text
- View/download PDF
26. High static magnetic field-assisted synthesis of Mn-doped ZnO diluted magnetic semiconductor via the hydrothermal method
- Author
-
Licheng Dong, Bangfei Zhou, Chunmei Liu, Zhe Shen, Tianxiang Zheng, and Yunbo Zhong
- Subjects
Condensed Matter Physics - Published
- 2023
27. Effect of Accelerated Fe-Rich Precipitation Induced by Ag Addition on the Microstructure and Comprehensive Properties of Cu–10 Wt Pct Fe Alloys
- Author
-
Junqi Shi, Lun Zhao, Liangguo Chen, Shunran Zhang, Zhongze Lin, Ganpei Tang, Lang Ren, Peijian Shi, Tianxiang Zheng, Yifeng Guo, Qiang Li, Zhe Shen, Biao Ding, and Yunbo Zhong
- Subjects
Mechanics of Materials ,Metals and Alloys ,Condensed Matter Physics - Published
- 2022
28. Influence of Annealing Temperature on the Magnetic Properties of One-dimensional Diluted Magnetic Semiconductor Zn0.95Mn0.05O Tuning with Vacuum Atmospheric Annealing
- Author
-
Licheng Dong, Chunmei Liu, Zhe Shen, Bangfei Zhou, Tianxiang Zheng, Qiang Li, and Yunbo Zhong
- Subjects
Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Published
- 2022
29. Phase Growth in Fe-Fe50wt%Si Diffusion Couple Under a Magnetic Field
- Author
-
Lijun, Fan, Yunbo, Zhong, Pengwei, Zhou, Tianxiang, Zheng, Qiong, Long, and The Minerals, Metals & Materials Society
- Published
- 2016
- Full Text
- View/download PDF
30. Refinement of Eutectic Carbides in M2 High Speed Steel by Adjusting Magnetic Flux Density During Magnetic Controlled ESR Process
- Author
-
Yifeng Guo, Wentao Qi, Zhibin Xia, Wenhao Lin, Chunmei Liu, Peijian Shi, Qiang Li, Zhe Shen, Biao Ding, Tianxiang Zheng, and Yunbo Zhong
- Subjects
Mechanics of Materials ,Materials Chemistry ,Metals and Alloys ,Condensed Matter Physics - Published
- 2022
31. Diffusion mechanism in liquid Al–Cu melt under high magnetic field.
- Author
-
Wenhao Lin, Meilong Feng, Ying Liu, Hao Cai, Zhe Shen, Chunmei Liu, Tianxiang Zheng, Bangfei Zhou, and Yunbo Zhong
- Subjects
MAGNETIC fields ,MASS transfer ,LIQUIDS ,MELTING ,LIQUID alloys - Abstract
High static magnetic field (HMF) is now a widely used technique to tailor materials. However, as one of the most fundamental properties in liquid alloy melts, atomic diffusion under HMF still lacks understanding. By using a novel gravity-assisted automatic docking device, the interdiffusion coefficient (IDC) in liquid Al–Cu alloy at various temperatures has been studied under HMF. It is found that HMF reduces the IDC. When HMF is larger than 5 T, the value of IDC remains constant at a certain temperature, which indicates HMF changes the diffusion mechanism from convective dominated mass transfer to a diffusive limited state in the liquid melt. For various temperatures, we find that a decrease of the frequency factor of atoms is the main reason for IDC decreasing under a certain HMF. The diffusion mechanism in liquid melt is similar to the vacancy mechanism in solids. This work provides a deep insight for atomic diffusion in a liquid melt by considering the interaction between temperature and HMF. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
32. Enhanced electrical, mechanical and tribological properties of Cu-Cr-Zr alloys by continuous extrusion forming and subsequent aging treatment
- Author
-
Zhu Jiale, Yifeng Guo, Tianxiang Zheng, Zhe Shen, Jianpei Shi, Biao Ding, Lin Zhongze, and Yunbo Zhong
- Subjects
Materials science ,Polymers and Plastics ,Mechanical Engineering ,Alloy ,Metals and Alloys ,Nanoindentation ,engineering.material ,Microstructure ,Indentation hardness ,Precipitation hardening ,Mechanics of Materials ,Ultimate tensile strength ,Materials Chemistry ,Ceramics and Composites ,engineering ,Extrusion ,Composite material ,Elastic modulus - Abstract
As a promising material for the new generation of high-speed railway contact wires, the comprehensive optimization of the electrical conductivity, strength, hardness and wear resistance of the Cu-Cr-Zr alloy has received extensive attention. In this paper, a high-performance Cu-1Cr-0.1Zr alloy with an ultimate tensile strength of 599.1 MPa, a uniform elongation of 8.6%, a microhardness of 195.7 HV0.2 and an electrical conductivity of 80.07%IACS was achieved by the continuous extrusion forming (CEF) and subsequent peak-aging treatment. The grain refinement strengthening, dislocation strengthening and precipitation strengthening are identified to be responsible for the excellent electrical and mechanical properties of Cu-Cr-Zr alloy. The wear behavior of Cu-Cr-Zr alloy was investigated by examining the evolution of worn surface morphology and subsurface microstructure. The microhardness (H) and reduced elastic modulus (Er) of the subsurface below the worn surface measured by nanoindentation were calculated to gauge the tribological performance of Cu-Cr-Zr alloy. Results show that the continuously extruded and subsequently peak-aged specimen has the best wear resistance, which indicates that the tribological properties of Cu-Cr-Zr alloy strongly depend on its strength and hardness. It can be concluded that the CEF and subsequent aging treatment process provides a new and high-efficiency procedure for the continuous preparation of Cu-Cr-Zr alloys.
- Published
- 2022
33. Inhibition of Cusp magnetic field on stray-crystal formation in platform region during directionally solidified single-crystal superalloy
- Author
-
Jianchao Peng, Ming Jian, Yunbo Zhong, Xiaotan Yuan, Tao Zhou, Tianxiang Zheng, Congjiang Zhang, Biao Ding, and Weili Ren
- Subjects
Cusp (singularity) ,Materials science ,Polymers and Plastics ,Computer simulation ,Condensed matter physics ,Mechanical Engineering ,Flow (psychology) ,Metals and Alloys ,law.invention ,Magnetic field ,Crystal ,Superalloy ,Flow velocity ,Mechanics of Materials ,law ,parasitic diseases ,Materials Chemistry ,Ceramics and Composites ,Crystallization - Abstract
The stray crystal in the platform region is one of the common main defects in single-crystal superalloy blades. The simple and effective method to eliminate this defect is urgent to be explored. This work found that the Cusp magnetic field can effectively inhibit the stray-crystal formation in the platform. The tendency of stray-crystal formation decreases as the magnetic-field strength increases at a certain withdrawal rate and temperature-gradient. The suppressing effect decreases as the withdrawal rate or the temperature-gradient increases. Finally, the inhibiting mechanism on the stray-crystal formation from the Cusp magnetic field is proposed based on the experiments and the numerical simulation. The magnetic-field application strengthens the flow velocity and changes the flow structure near the liquid-solid interface, and further reduces the radial temperature difference. Accordingly, the secondary dendrites in the heat-conduction undercooled zone expands towards the corner in a faster speed, which reduces the stray-crystal formation in the platform corner. This study provides an effective and simple method for decreasing the stray-crystal formation during the preparation of single-crystal with platform region.
- Published
- 2022
34. Ex-situ study of diffusion in liquid Al–Cu melts under a transverse magnetic field using X-ray imaging
- Author
-
Ying Liu, Wenhao Lin, Bangfei Zhou, Xianghui Guo, Hao Cai, Tianxiang Zheng, Biao Ding, Yunbo Zhong, and Lei Zhang
- Subjects
Condensed Matter Physics - Published
- 2022
35. Motion and removal behavior of inclusions in electrode tip during magnetically controlled electroslag remelting: X-ray microtomography characterization and modeling verification
- Author
-
Qiang Li, Zhibin Xia, Yifeng Guo, Yunbo Zhong, Shaogang Wang, Zhe Shen, W.F. Liu, Tianxiang Zheng, Biao Ding, and Mingyue Sun
- Subjects
Work (thermodynamics) ,Materials science ,Polymers and Plastics ,Mechanical Engineering ,Metals and Alloys ,02 engineering and technology ,Edge (geometry) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Kinetic energy ,01 natural sciences ,0104 chemical sciences ,Matrix (geology) ,Characterization (materials science) ,Mechanics of Materials ,Electrode ,Materials Chemistry ,Ceramics and Composites ,Slag (welding) ,Inclusion (mineral) ,Composite material ,0210 nano-technology - Abstract
Detailed three-dimensional (3D) microtomography characterizations of inclusions in electrode matrix, mushy zone (MZ) and liquid melt film (LMF) were performed to elucidate the motion and removal behavior of inclusions in electrode tip during magnetically controlled electroslag remelting (MC-ESR) process. A transient 2D numerical model was also built to verify the experimental results and proposed mechanisms. The number and size of inclusions exhibited an obvious increasing trend from edge to mid region in LMF, while remained almost the same in electrode matrix and MZ. The inclusions in LMF migrated from edge to mid region of LMF, accompanied with removal process. In addition, the kinetic conditions for inclusion migrating to LMF/slag interface (LSI) were enhanced during MC-ESR process, thereby improving the inclusion removal efficiency in LMF. This work highlights the 3D characterization and motion/removal mechanisms of inclusions in electrode tip, as well as sheds new light on preparing high purity materials.
- Published
- 2022
36. Primary-Dendrite-Pattern Regulation by Secondary Branch During the Directional Solidification of the Single Crystal Superalloy
- Author
-
Xiaotan Yuan, Xingjin Hu, Congjiang Zhang, Hongbin Yu, Weili Ren, Biao Ding, Haibiao Lu, Yunbo Zhong, Zuosheng Lei, Hui Wang, Qiuliang Wang, Peter K. Liaw, Xuezhi Qin, and Lanzhang Zhou
- Published
- 2023
37. Enhancement of Inclusion Removal in Electroslag Remelted M2 High-Speed Steel Assisted by Axial Static Magnetic Field
- Author
-
Yifeng Guo, Tianxiang Zheng, Zhe Shen, Zhibin Xia, Biao Ding, Yunbo Zhong, and Qiang Li
- Subjects
symbols.namesake ,Structural material ,Materials science ,Mechanics of Materials ,Metallic materials ,Metallurgy ,Metals and Alloys ,symbols ,Inclusion (mineral) ,Condensed Matter Physics ,Magnetostatics ,Lorentz force ,High-speed steel - Abstract
The effect of axial static magnetic field (ASMF) on inclusion removal during the magnetically controlled electroslag remelting M2 high-speed-steel was investigated. The results showed that the application of ASMF can significantly increase the inclusion removal efficiency, especially for the inclusions larger than 20 μm. The reason for the accelerated removal of inclusions was attributed to the alternating Lorentz force and the magnetically controlled spin-vibration induced in the liquid melt film after the application of ASMF.
- Published
- 2021
38. A precipitate-free AlCoFeNi eutectic high-entropy alloy with strong strain hardening
- Author
-
Ningning Liang, Yuebo Wen, Zhe Shen, Pengfei Hu, Tianxiang Zheng, Peter K. Liaw, Yi Li, Long Hou, Qingdong Liu, Weili Ren, Peijian Shi, Jianchao Peng, Yifeng Guo, Yiqi Li, Yunbo Zhong, Ying Jiang, and Yan Wang
- Subjects
Materials science ,Polymers and Plastics ,Mechanical Engineering ,Alloy ,Metals and Alloys ,02 engineering and technology ,Strain hardening exponent ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Microstructure ,01 natural sciences ,0104 chemical sciences ,Mechanics of Materials ,Ultimate tensile strength ,Materials Chemistry ,Ceramics and Composites ,engineering ,Lamellar structure ,Composite material ,Deformation (engineering) ,0210 nano-technology ,Castability ,Eutectic system - Abstract
Over recent years, eutectic high-entropy alloys (EHEAs) have intrigued substantial research enthusiasms due to their good castability as well as balanced strength–ductility synergy. In this study, a bulk cast Al19.25Co18.86Fe18.36Ni43.53 EHEA is developed with fine in-situ lamellar eutectics. The eutectics comprise alternating ordered face-centered-cubic (L12) and ordered body-centered-cubic (B2) phases with semi-coherent interfaces. The resulting microstructure resembles that of most reported as-cast EHEAs, but the B2 lamellae are devoid of nano-precipitates because of the Cr-element removal in current tailored eutectic composition. Surprisingly, the B2 lamellae still feature much higher deformation resistance than the L12 lamellae, so that less lattice defects are detected in the B2 lamellae until the fracture. More interestingly, in the L12 lamellae we identify a dynamic microstructure refinement that correlates to extraordinary strain hardening in tension. The precipitate-free EHEA consequently shows excellent tensile ductility of ∼10 % and high ultimate strength up to ∼956 MPa.
- Published
- 2021
39. Effect of axial static magnetic field on cleanliness and microstructure in magnetically controlled electroslag remelted bearing steel
- Author
-
Biao Ding, Yifeng Guo, Yunbo Zhong, Zhe Shen, Qiang Li, Tianxiang Zheng, and Zhibin Xia
- Subjects
Bearing (mechanical) ,Materials science ,Metals and Alloys ,Magnetostatics ,Microstructure ,Magnetic field ,law.invention ,Rockwell scale ,Mechanics of Materials ,law ,Ultimate tensile strength ,Electrode ,Materials Chemistry ,Composite material ,Molten pool - Abstract
The effect of the axial static magnetic field (ASMF) on cleanliness and microstructure in magnetically controlled electroslag remelted GCr15 bearing steel ingots was investigated experimentally. The results show that a magnetically controlled spin-vibration induced by the interaction of the ASMFs and the remelting current exists at the consumable electrode tip, resulting in thinner liquid melt film and smaller droplets. With the increase in magnetic flux density, the optimization effect of ASMFs on electroslag remelting process increases and reaches the peak with a 40 mT ASMF, then decreases. The cleanliness of the ingots was improved, and the count of inclusions larger than 5 μm was reduced. The microstructure of the ingots processed with a 40 mT ASMF was significantly refined. The depth of the metallic molten pool was reduced from 45.2 to 17.5 mm with the application of 40 mT ASMF. The tensile strength, impact toughness, and Rockwell hardness of the ingots obtained under the 40 mT ASMF were significantly improved. The mechanisms of the spin-vibration occurring at the electrode tip end were interpreted in detail to elucidate the effect of ASMFs.
- Published
- 2021
40. Hierarchical crack buffering triples ductility in eutectic herringbone high-entropy alloys
- Author
-
Zhe Shen, Weili Ren, Peijian Shi, Xue Liang, Pengfei Hu, Yandong Wang, Yuebo Wen, Dierk Raabe, Na Min, Tianxiang Zheng, Yong Zhang, Yi Li, Runguang Li, Yunbo Zhong, Yang Ren, Peter K. Liaw, and Jianchao Peng
- Subjects
Multidisciplinary ,Materials science ,High entropy alloys ,Percolation ,Nucleation ,Elongation ,Composite material ,Ductility ,Microstructure ,Tensile testing ,Eutectic system - Abstract
In human-made malleable materials, microdamage such as cracking usually limits material lifetime. Some biological composites, such as bone, have hierarchical microstructures that tolerate cracks but cannot withstand high elongation. We demonstrate a directionally solidified eutectic high-entropy alloy (EHEA) that successfully reconciles crack tolerance and high elongation. The solidified alloy has a hierarchically organized herringbone structure that enables bionic-inspired hierarchical crack buffering. This effect guides stable, persistent crystallographic nucleation and growth of multiple microcracks in abundant poor-deformability microstructures. Hierarchical buffering by adjacent dynamic strain-hardened features helps the cracks to avoid catastrophic growth and percolation. Our self-buffering herringbone material yields an ultrahigh uniform tensile elongation (~50%), three times that of conventional nonbuffering EHEAs, without sacrificing strength.
- Published
- 2021
41. Morphology Tailoring and Enhanced Inclusion Removal of Liquid Melt Film by Regulating the Magnetic Flux Density During Magnetic Controlled ESR Process
- Author
-
Zhe Shen, Yifeng Guo, Zhibin Xia, Chengkuan Ma, Tianxiang Zheng, Yunbo Zhong, Biao Ding, Chunmei Liu, Wentao Qi, and Qiang Li
- Subjects
Work (thermodynamics) ,Materials science ,Structural material ,Morphology (linguistics) ,Metals and Alloys ,Condensed Matter Physics ,Kinetic energy ,Magnetostatics ,Magnetic field ,Transverse plane ,Mechanics of Materials ,Materials Chemistry ,Composite material ,Inclusion (mineral) - Abstract
The current study focuses on the influences of magnetic flux density (MFD) on liquid melt film (LMF) morphology and inclusion removal during magnetic controlled electroslag remelting (MC-ESR) process (GCr15 bearing steel). The average thickness of LMF was reduced by 21.0, 33.0 and 41.3 pct, respectively, after applying a 35, 65 and 95 mT transverse static magnetic field (TSMF). This phenomenon can be attributed to the accelerated dynamic process (LMF aggregating to form droplet and droplet dripping) under TSMF condition, which was more obvious as larger MFD was applied. In addition, the kinetic conditions for inclusion removal in LMF were also enhanced with the increase of the MFD (0 to 95 mT), leading to a gradual decrease in the number and size of inclusions in LMF. This work highlights the LMF morphology tailoring and inclusions removal enhancement by regulating the MFD of applied TSMF as well as guides the industrial application of MC-ESR technology.
- Published
- 2021
42. Numerical Simulation of In-mold Electromagnetic Stirring on Slide Gate Caused Bias Flow and Solidification in Slab Continuous Casting
- Author
-
Haibiao Lu, Zuosheng Lei, Zhongming Ren, Li Jiaxun, Bin Li, and Yunbo Zhong
- Subjects
Materials science ,Computer simulation ,Mechanical Engineering ,Flow (psychology) ,Metals and Alloys ,medicine.disease_cause ,Continuous casting ,Electromagnetic stirring ,Mechanics of Materials ,Mold ,Materials Chemistry ,Slab ,medicine ,Composite material - Published
- 2021
43. Carbides Modification and Mechanical Properties Enhancement of Cr12MoV Die Steel by Magnetically Controlled Electroslag Remelting
- Author
-
Tianxiang Zheng, Yifeng Guo, Zhe Shen, Zhibin Xia, Qiang Li, Biao Ding, and Yunbo Zhong
- Subjects
business.product_category ,Materials science ,Structural material ,Metals and Alloys ,Condensed Matter Physics ,Magnetostatics ,Magnetic field ,Carbide ,Dendrite (crystal) ,Mechanics of Materials ,Thermoelectric effect ,Materials Chemistry ,Die (manufacturing) ,Ingot ,Composite material ,business - Abstract
The effects of an axial static magnetic field (ASMF) on the carbides and mechanical properties of electroslag-remelted (ESR) Cr12MoV die steel were investigated. The superimposition of a 30 mT ASMF induced unidirectional rotation in the molten slag pool, resulting in a more uniform temperature distribution at the front of the dendrite solid–liquid interface. The size of the grains and carbides in the ESR Cr12MoV steel ingot became smaller. The sulfur content of the ingots decreased and the mechanical properties (hardness and impact energy) increased after applying the ASMF. A new mechanism was proposed that the unidirectional flow was mainly due to the coupled thermoelectric magnetic force induced in the melt between dendrites, which promoted the refinement of grains and carbides, as well as the desulfurization process, thereby resulting in the enhanced mechanical properties of the Cr12MoV die steel.
- Published
- 2021
44. Morphology transition of eutectic carbide assisted by thermoelectric magnetic force during the directional solidification of M2 high-speed steel
- Author
-
Tianxiang Zheng, Yunbo Zhong, Yifeng Guo, Wanqin Li, Zhibin Xia, Qiuliang Wang, Zhe Shen, Wentao Qi, Qiang Li, and Hui Wang
- Subjects
010302 applied physics ,Materials science ,Mechanical Engineering ,0211 other engineering and technologies ,Metals and Alloys ,02 engineering and technology ,Magnetostatics ,Microstructure ,01 natural sciences ,Magnetic field ,Carbide ,Mechanics of Materials ,0103 physical sciences ,Thermoelectric effect ,Materials Chemistry ,Composite material ,021102 mining & metallurgy ,Eutectic system ,High-speed steel ,Directional solidification - Abstract
The morphology of eutectic carbide was studied by application of a transverse static magnetic field (TSMF) during the directional solidification of M2 high-speed steel. The results show that the mo...
- Published
- 2021
45. Enhanced strength and toughness of Ni/graphene composite via three-dimensional graphene-like nanosheets network
- Author
-
Zhongze Lin, Shunran Zhang, Lang Ren, Zhe Shen, Ganpei Tang, Peijian Shi, Tianxiang Zheng, Biao Ding, Yifeng Guo, Yan Chen, Qiang Li, Jianchao Peng, and Yunbo Zhong
- Subjects
Mechanics of Materials ,Mechanical Engineering ,Ceramics and Composites ,Industrial and Manufacturing Engineering - Published
- 2023
46. Precipitation Behavior of Nitride Inclusions in K418 Alloy under the Continuous Unidirectional Solidification Process
- Author
-
Zhongming Ren, Li Xia, Kang Deng, Yunbo Zhong, Wencheng Zhao, Yuan Hou, Yang Fan, Jianbo Yu, Qiang Li, and Xiliang Guo
- Subjects
Materials science ,Mechanics of Materials ,Precipitation (chemistry) ,Mechanical Engineering ,Scientific method ,Alloy ,Unidirectional solidification ,Metallurgy ,Materials Chemistry ,Metals and Alloys ,engineering ,Nitride ,engineering.material - Published
- 2021
47. Nondestructive effect of the cusp magnetic field on the dendritic microstructure during the directional solidification of Nickel-based single crystal superalloy
- Author
-
Long Hou, Zhongming Ren, Tao Zhou, Jianbo Yu, Weili Ren, Jianchao Peng, Tianxiang Zheng, Yunbo Zhong, Xiaotan Yuan, and Peter K. Liaw
- Subjects
Materials science ,Polymers and Plastics ,Mechanical Engineering ,Metals and Alloys ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Microstructure ,01 natural sciences ,0104 chemical sciences ,Magnetic field ,Superalloy ,Crystal ,Dendrite (crystal) ,Transverse plane ,Mechanics of Materials ,Materials Chemistry ,Ceramics and Composites ,Composite material ,0210 nano-technology ,Single crystal ,Directional solidification - Abstract
The mechanical-property improvement of directionally-solidified Nickel-based single crystal (SC) superalloy with the single-direction magnetic fields is limited by their destructiveness on the dendritic microstructure. Here, the work present breaks through the bottleneck. It shows that the application of the cusp magnetic field (CMF) ensures that the dendrites are not destroyed. This feature embodies that the primary dendrite trunks arrange regularly and orderly, as well the secondary dendrite arms grow symmetrically. By contrast, both the unidirectional transverse and longitudinal magnetic field destroy the dendrite morphology, and there are a number of stray grains near the totally-remelted interface. The nondestructive effect is achieved mainly by the combined action of the thermoelectromagnetic force on the dendrites and thermoelectromagnetic convection in the melt during directional solidification. The investigation should contribute a new route for dramatically and effectively improving the crystal quality and mechanical properties of the directionally-solidified alloys.
- Published
- 2021
48. Multistage work hardening assisted by multi-type twinning in ultrafine-grained heterostructural eutectic high-entropy alloys
- Author
-
Weili Ren, Bing Yang, Tianxiang Zheng, Peter K. Liaw, Yi Li, Jianchao Peng, Peijian Shi, Yuntian Zhu, Yong Zhang, Yunbo Zhong, Zhe Shen, and Pengfei Hu
- Subjects
Materials science ,Mechanical Engineering ,High entropy alloys ,02 engineering and technology ,Work hardening ,Strain hardening exponent ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Strength of materials ,0104 chemical sciences ,Mechanics of Materials ,Hardening (metallurgy) ,General Materials Science ,Composite material ,0210 nano-technology ,Crystal twinning ,Stacking fault ,Eutectic system - Abstract
High strength of materials usually comes with low ductility due to the lost or short-lived strain hardening. Here, we uncover a sequentially-activated multistage strain hardening (SMSH) that allows for sustained and effective strain-hardening capability in strong ultrafine-grained eutectic high-entropy alloy (EHEA). Consequently, exceptional ductility is realized in an ultrafine-grained EHEA, accompanied with high ultimate strength. We demonstrate that the SMSH is derived from a coordinated three-level design on structural heterogeneity, grain-size control, and intragranular composition modification, which enables the sequential activation of stress-dependent multiple hardening mechanisms. Furthermore, despite the well-known low twinning propensity due to ultrafine grains and medium-to-high stacking fault energies of prototype EHEAs, our coordinated design sequentially activates three types of deformation twinning to assist this SMSH. This work sheds light on the SMSH effect assisted by multi-type twinning previously unexpected in ultrafine-grained EHEAs, and thereby represents a promising route for improving ductility of high-strength materials.
- Published
- 2020
49. Microstructure Evolution and Mechanical Properties Improvement in Magnetic-controlled Electroslag Remelted Bearing Steel
- Author
-
Zhe Shen, Zhibin Xia, Yifeng Guo, Tianxiang Zheng, Qiang Li, and Yunbo Zhong
- Subjects
Bearing (mechanical) ,Materials science ,Mechanics of Materials ,law ,Mechanical Engineering ,Metallurgy ,Materials Chemistry ,Metals and Alloys ,Microstructure ,law.invention - Published
- 2020
50. Effects of Axial Static Magnetic Field on Inclusions Removal in the Liquid Melt Film During Electroslag Remelting Process
- Author
-
Yunbo Zhong, Yifeng Guo, Zhibin Xia, Zuosheng Lei, Qiang Li, Tianxiang Zheng, Zhe Shen, Weili Ren, and ChuXiong Sun
- Subjects
010302 applied physics ,Materials science ,Structural material ,Computer simulation ,0211 other engineering and technologies ,Metals and Alloys ,02 engineering and technology ,Condensed Matter Physics ,Magnetostatics ,01 natural sciences ,Mechanics of Materials ,Scientific method ,0103 physical sciences ,Metallic materials ,Materials Chemistry ,Composite material ,Inclusion (mineral) ,021102 mining & metallurgy - Abstract
Magnetic-controlled Electroslag Remelting (MC-ESR) process has been proposed to improve the inclusion removal efficiency in recent years. In this study, the effects of axial static magnetic field (ASMF) on liquid melting film (LMF) and inclusion removal during this period in ESR process of GCr15 steel were studied by a series of MC-ESR experiments. The thickness of the characteristic position of LMF was reduced by 18.6 to 90.3 pct when a 50 mT ASMF was applied. The number and size of the inclusions in LMF were also decreased. In addition, the mechanisms of LMF thinning and inclusion removal efficiency improvement enhanced by the ASMF were interpreted in detail. Furthermore, a numerical simulation of the inclusion migration in LMF was also carried out to support the proposed mechanisms to some extent.
- Published
- 2020
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.