10 results on '"Liu, Fengchao"'
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2. Dual-phase synergistic deformation characteristics and strengthening mechanism of AlCoCrFeNi2.1 eutectic high entropy alloy fabricated by laser powder bed fusion.
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Tang, Xu, Zhang, Hao, Zhu, Zhengwang, Xue, Peng, Wu, Lihui, Liu, Fengchao, Ni, Dingrui, Xiao, Bolv, and Ma, Zongyi
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STRAIN hardening ,TENSILE strength ,FACE centered cubic structure ,ENTROPY ,DEFORMATIONS (Mechanics) - Abstract
• The optimum process parameters for preparing AlCoCrFeNi 2.1 were determined. • Formation mechanism of regular eutectic lamella of AlCoCrFeNi 2.1 was revealed. • The printed AlCoCrFeNi 2.1 possessed excellent match of strength and plasticity. • The strain hardening effect caused by synergistic deformation was emphasized. Eutectic high entropy alloy (EHEA) possesses promising prospects for industrial application due to its controllable and near-equilibrium dual-phase structure. Due to the advantages of high material utilization, efficient production, and design freedom, the laser powder bed fusion (LPBF) technique provides a new path to prepare EHEA components with complex structure and excellent performance. In this study, near fully dense AlCoCrFeNi 2.1 samples were obtained by adjusting the process parameters of LPBF. Considering the balling phenomenon and powder splashing during the LPBF process, laser remelting was selected as an optimized scanning strategy to further improve the forming quality of AlCoCrFeNi 2.1. The microstructure of remelted AlCoCrFeNi 2.1 sample exhibited regular eutectic lamellae consisting of nano-scale face-centered-cubic (FCC) and B2 phases, in which the FCC phase accounted for a higher proportion. By investigating the tensile behavior and deformation mechanism, it was revealed that the ultrafine eutectic lamellae could induce a strong dual-phase synergistic strengthening, thereby significantly improving the strength of the sample. Compared with the vacuum induction melted (VIM) sample, the remelted sample showed a 54% increase in ultimate tensile strength (UTS -1518 MPa) and a 130% increase in yield strength (YS -1235 MPa) with reasonable plasticity. This study indicates that by combining the design and manufacturing freedom of LPBF with the EHEA, it is expected to fabricate high-property 3D EHEA parts, expanding the application field of EHEA. [ABSTRACT FROM AUTHOR]
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- 2023
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3. Microstructure evolution and mechanical properties of nanocrystalline zirconium processed by surface circulation rolling treatment
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Yuan, Chao, Fu, Ruidong, Zhang, Fucheng, Zhang, Xiangyi, and Liu, Fengchao
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- 2013
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4. 3D printing of fine-grained aluminum alloys through extrusion-based additive manufacturing: Microstructure and property characterization.
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Liu, Fengchao, Dong, Pingsha, Khan, Abdul Sayeed, Zhang, Yuning, Cheng, Randy, Taub, Alan, and Ma, Zongyi
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ALUMINUM alloys ,THREE-dimensional printing ,SUSTAINABILITY ,HEAT treatment ,MICROSTRUCTURE ,INJECTION molding of metals - Abstract
• A new extrusion-based solid-state metal additive manufacturing method was developed. • The new method enables direct deposition of fine-grained aluminum alloy without melting. • The new method uses off-the-shelf metal rods rather than pricy powders as feedstock. • The printing process was completed in an open-air environment, avoiding costly inert or vacuum conditions. • The printed 6061 aluminum alloys yield the strength and ductility comparable to wrought 6061 aluminum alloys. Additive manufacturing (AM) has the potential to transform manufacturing by enabling previously unthinkable products, digital inventory and delivery, and distributed manufacturing. Here we presented an extrusion-based metal AM method (refer to "SoftTouch" deposition in the filed patent) that is suitable for making the metal feedstock flowable prior to the deposition through dynamic recrystallization induced grain refinement at elevated temperatures. The flowable metal was extruded out of the printer head like a paste for building dense metal parts with fine equiaxed grains and wrought mechanical properties. Off-the-shelf metal rods were used as feedstock and the printing process was completed in an open-air environment, avoiding pricy powders and costly inert or vacuum conditions. The resulting multi-layer deposited 6061 aluminum alloys yield strength and ductility comparable to wrought 6061 aluminum alloys after the same T6 heat treatment. The extrusion-based metal AM method can also be advanced as green manufacturing technologies for fabricating novel alloys and composites, adding novel features to existing parts, repairing damaged metal parts, and welding advanced metals for supporting sustainable manufacturing, in addition to being developed into a cost-effective manufacturing process for the fabrication of dense metal of complex structural forms. [Display omitted] [ABSTRACT FROM AUTHOR]
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- 2023
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5. A regional perspective on the structural transformation of China's national innovation system since 1999
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Sun, Yutao and Liu, Fengchao
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High technology industry ,Social sciences - Abstract
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.techfore.2010.04.012 Byline: Yutao Sun, Fengchao Liu Keywords: National Innovation System; China; Structural transformation; 8LERs; RSC Abstract: Observing the structural transformation of China's National Innovation System (NIS) since 1999 is useful for understanding the rapid economic growth experienced in China and for adjusting the development strategies of other late-industrializing countries. The following article uses the regional specialization coefficient (RSC) method to analyze the structural transformation of China's NIS from the perspective of eight large economic regions (8LERs) from 1999 to 2006. The NIS has achieved its initial objectives and two of the three major characteristics of China's NIS identified in Sun's (2002) [1] paper have changed since 1999: the funding structure -- from a government- to an enterprise-centered model; and the performing structure -- from a double-centered model divided into enterprises and research institutions, to one solely led by enterprise. The regional structures of China's innovation system conform to the macro structure on a national level, while regionally, a wide variety of changing models of RSC affect different locales. The Chinese central government remains the leading force in reforming its innovation system with 'Chinese Characteristics'. Author Affiliation: Innovation and Development Research Center, School of Management, Dalian University of Technology, Dalian 116024, China Article History: Received 15 August 2009; Revised 13 January 2010; Accepted 4 April 2010
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- 2010
6. A comparison of the spatial distribution of innovative activities in China and the U.S
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Liu, Fengchao and Sun, Yutao
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Waterfront development -- Innovations ,Waterfront development -- Comparative analysis ,Developing countries -- Comparative analysis ,Universities and colleges -- Comparative analysis ,High technology industry ,Social sciences - Abstract
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.techfore.2008.12.002 Byline: Fengchao Liu, Yutao Sun Keywords: China and the U.S.; Innovation; Spatial distribution; Rank -frequency; Concentration Abstract: In order to enhance the independent innovation capability and help China to become an 'innovation-oriented country' this article compares the spatial distribution of innovative activities between China (representing a typical developing country) and the United States. We also provide some recommendations for China and other developing countries to optimize the spatial distribution of their innovative activities. Using invention patents as an indicator gathered from the websites of the CSIPO and the USPTO, this paper compares the spatial distribution of innovative activity in China and the U.S. by methods such as rank-frequency, concentration and classification. The results show that the invention patents have experienced rapid growth and significant fluctuation in recent years in China, while the United States has been relatively stable. The spatial diversity of patent distribution in China is more obvious than in the United States. There is a concentrated trend of innovative activities in both China and the United States from the inland areas to the coastal regions. Author Affiliation: Innovation and Development Research Center, School of Management, Dalian University of Technology, Dalian 116024, China Article History: Received 11 September 2008; Revised 10 December 2008; Accepted 15 December 2008 Article Note: (footnote) [star] This paper is a part of the project (70773014) funded by the National Natural Science Foundation of China and the program named 'High-level Government-sponsored Overseas Study for Postgraduates' funded by the China Scholarship Council.
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- 2009
7. TGF-β1 acts through miR-155 to down-regulate TP53INP1 in promoting epithelial–mesenchymal transition and cancer stem cell phenotypes.
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Liu, Fengchao, Kong, Xin, Lv, Lin, and Gao, Jian
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CANCER stem cells , *CANCER invasiveness , *TRANSFORMING growth factors , *MICRORNA , *DOWNREGULATION , *EPITHELIAL cells , *PHENOTYPES - Abstract
It has been shown that acquisition of epithelial–mesenchymal transition (EMT) and induction of cancer stem cell (CSC)-like properties contribute to metastasis of cancers in many studies; however, the molecular mechanisms underlying EMT and CSC phenotypes in liver cancer cells remain to be elucidated. MiR-155 is an important microRNA associated with tumour progression. Here, we report that miR-155 regulates not only the epithelial–mesenchymal transition but also the stem-like transition in liver cancer cells. Utilizing quantitative RT-PCR, we found that the expression of miR-155 is positively related to the levels of CD90, CD133 and Oct4 in enriched spheres. Up-regulated miR-155 significantly increases the population of stem-like CSCs among liver cancer cells and the ability to form tumour spheres. Additionally, miR-155 overexpression in cells significantly increases cell motility and invasion, as well as the epithelial–mesenchymal transition process. Conversely, suppression of miR-155 in cells had an opposite effect, which was partially rescued by the down-regulation of TP53INP1. Collectively, miR-155 promotes liver cancer cell EMT and CSCs, in part, via silencing TP53INP1. In addition, we found that TGF-β1 indirectly regulates TP53INP1 expression via miR-155 in liver cancer cells. Taken together, our findings suggest that miR-155 regulates TP53INP1 expression, to induce the epithelial–mesenchymal transition and acquisition of a stem cell phenotype. [ABSTRACT FROM AUTHOR]
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- 2015
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8. Interprovincial two-stage water resource utilization efficiency under environmental constraint and spatial spillover effects in China.
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Zhao, Liangshi, Sun, Caizhi, and Liu, Fengchao
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WATER supply , *WATER use & the environment , *ECONOMETRIC models , *RESIDENTIAL water consumption , *WATER consumption ,ENVIRONMENTAL aspects - Abstract
Although existing studies have paid much attention to the measurement model of water resource utilization efficiency, they have failed to consider the spatial spillover effect of some influencing factors of water resource utilization efficiency, causing biased results. This study measures the water resource utilization efficiency of 31 provincial administrative regions in China from 2001 to 2014 and the efficiency of each stage by adopting a slack-based efficiency evaluation model based on the relaxation of two stages to consider undesirable output. Then, this study employs a spatial Durbin econometric model by considering spatial effect to analyze the influencing factors of the overall efficiency of water resource utilization by per capita water resources, industrial water, living water consumption, per capita gross domestic product, degree of opening to the outside world, industrial structure, technological progress, and other aspects. By comparison, existing studies do not consider the spatial spillover effect. This study estimates the direct and indirect effects of the influencing factors of water resource utilization efficiency to distinguish local and neighbors' impacts of influencing factors of water resource utilization efficiency. The results are as follows. (1) First-stage overall efficiency is significantly higher than second-stage water resource utilization efficiency, overall efficiency is close to second-stage efficiency, and second-stage efficiency determines the overall effectiveness of water resource utilization. (2) The spatial autocorrelation intensity of water resource utilization overall efficiency is significantly greater than zero, and water resource utilization overall efficiency presents concentration distribution in the space for which the eastern coastal regions are high–high type and the central and western regions are low–low type. (3) The overall efficiency of water resource utilization has spatial spillover effects, and the region's overall efficiency is influenced by both region and neighborhood region. (4) The direct and indirect effects of domestic water consumption, degree of opening up, and industrial structure are the primary significant influencing factors of overall efficiency of water resources in China. The spatial spillover effects of domestic water consumption and industrial structure have a significant impact. To improve water resource utilization efficiency, the government and citizens should focus on such solutions as pollution reduction, domestic water savings, and transforming the industrial structure. Moreover, China should consider the spatial effects of these influencing factors when government policies are designed. [ABSTRACT FROM AUTHOR]
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- 2017
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9. Microstructure and mechanical properties of Ti–Zr–Cr biomedical alloys.
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Wang, Pan, Feng, Yan, Liu, Fengchao, Wu, Lihong, and Guan, Shaokang
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TITANIUM compounds , *CHROMIUM , *MICROSTRUCTURE , *MICROHARDNESS , *MECHANICAL alloying , *BIOMEDICAL materials - Abstract
The Ti–15Zr– x Cr (0 ≤ x ≤ 10, wt.%) alloys were investigated to develop new biomedical materials. It was found that the phase constitutions and mechanical properties strongly depended on the Cr content. The Ti–15Zr alloy was comprised of α′ phase and a small fraction of β phase was detected with adding 1 wt.% Cr. With addition of 5 wt.% or more, the β phase was completely retained. In addition, the ω phase was detected in the Ti–15Zr–5Cr alloy and Ti–15Zr–7Cr alloy which exhibited the highest compressive Young's modulus and the lowest ductility. On the other hand, all the Ti–15Zr– x Cr alloys without ω phase exhibited high microhardness, high yield strength and superior ductility. Furthermore, the elastic energy of Ti–15Zr–10Cr alloy (5.89 MJ/m 3 ) with only β phase and that of Ti–15Zr–3Cr alloy (4.04 MJ/m 3 ) with α′ phase and small fraction of β phase was higher than the elastic energy of c.p. Ti (1.25 MJ/m 3 ). This study demonstrated that Ti–15Zr–3Cr alloy and Ti–15Zr–10Cr alloy with superior mechanical properties are potential materials for biomedical applications. [ABSTRACT FROM AUTHOR]
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- 2015
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10. Friction-based processes for hybrid multi-material joining.
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Lambiase, Francesco, Balle, Frank, Blaga, Lucian-Attila, Liu, Fengchao, and Amancio-Filho, Sergio T.
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JOINING processes , *SURFACE preparation , *ULTRASONIC welding , *FRICTION welding , *DEAD loads (Mechanics) , *ENERGY consumption , *DYNAMIC loads - Abstract
The adoption of multi-material lightweight structures has been recognized as one of the most effective and promising solutions to improve fuel efficiency and accelerate the electrification of future transportation systems. A wider application of multi-material lightweight structures has been limited by our capability to fabricate them reliably and cost-effectively at a commercial scale. In the last decade, many friction-based joining processes have been developed and demonstrated their advantages over mechanical fastening and adhesive bonding processes in fabricating future multi-material lightweight structures. This article provides a comprehensive review on the recent advances of five promising friction-based joining processes (friction assisted joining, friction lap welding, friction spot joining, friction riveting, and ultrasonic welding) on the aspects of facilities, joining process, joining mechanism, applicable materials, surface pretreatments, and the influence of process parameters on the performance of the produce joints. This article also provides a summary of the performance of the produced joints under static load, dynamic load, various thermal cycles, or harsh chemical environments. The main similarities and differences among the joining processes are discussed. The paper points out the main knowledge gaps that need to be filled and the research that needs to be conducted to further advance the joining process. This review article will place the friction-based joining process at a new starting point with accelerated developing speed towards higher technical maturity to make the processes available for certifiable industrial applications. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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