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Effect of Heat Treatment on the Microstructure and Mechanical Properties of the Modified 718 Alloy

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Acta Metallurgica Sinica(English Letters) 2018年第11期31卷 1224-1232页

作者： da-wei han Lian-Xu Yu Fang Liu Bin Zhang Wen-Ru Sun School of Materials Science and Engineering Northeastern University Shenyang 110819 China Chongqing Skyrizon Aero-engine Co. Ltd Chongqing 401135 China Institute of Metal Research Chinese Academy of SciencesShenyang 110016 China

M718 alloy with an extra high Mo content of 7.50 wt% which reduced Nb addition and increased A1 and Ti additionswithin the composition specifications of 718 alloy has been designed to increase the service temperature of 718 alloy. Andthe effect of the heat treatment on the microstructure and mechanical properties of M718 alloy has been investigated in thisstudy. The results showed that Laves phase precipitated on the grain boundaries of M718 alloy instead of 6-Ni3Nb phase in718 alloy, and γ″ and γ′ phases precipitated in the matrix of M718 alloy as that in 718 alloy. Increasing the solutiontemperature from 960 to 1050 ℃ noticeably reduced the intergranular precipitation of Laves phase. The precipitation ofLaves phase was appropriate at 1020 ℃ for improving the grain boundary cohesion. Increasing the two-stage agingtemperatures markedly increased the sizes of γ″ and γ′ phases. As a result, the strength of M718 alloy increased.

关键词： Heat treatment Mo 718 alloy Microstructure Mechanical properties

Element Segregation and Solidification Behavior of a Nb, Ti, Al Co-Strengthened Superalloy ЭК151

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Acta Metallurgica Sinica(English Letters) 2019年第10期32卷 1298-1308页

作者： Yuan-Guo Tan Fang Liu An-Wen Zhang da-wei han Xiao-Yu Yao wei-wei Zhang Wen-Ru Sun Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China University of Science and Technology of China Hefei 230026 China

The as-cast microstructure, element segregation and solidification behavior of a multi-alloyed superalloy ЭК151 have been investigated. The results show that the severe element segregation leads to the complicated precipitations at the inter-dendritic region, including η-Ni3(Ti, Nb), eutectic(γ + γ’) and Laves, which shows the characteristics of both Ti, Al-strengthened and Nb-strengthened alloys. Differential thermal analysis, heating and quenching tests reveal the solidification sequence as follows: Liquids →γ matrix →(Nb, Ti)C →η-Ni 3(Ti, Nb) →eutectic( γ+γ’) → Laves. The melting points are between 1250 and 1260 °C for(Nb, Ti)C, between 1200 and 1210 °C for η phase, between 1180 and 1190 °C for eutectic(γ+γ’) and Laves. γ’ initially precipitates from matrix at 1150 °C and achieves the maximum precipitation at 1130 °C. According to the microstructure evolution captured during solidification and composition analysis by an energy dispersive spectrometer and electron probe microanalyzer,(Nb, Ti)/Al ratio is put forward to explain the formation of η-Ni3(Ti, Nb) and eutectic( γ+γ’). The solidification of γ matrix increased the Nb, Ti concentration in the residual liquids, so the high(Nb, Ti)/Al ratio would result in the formation of η-Ni3(Ti, Nb); the precipitation of the phase consumed Nb and Ti and decreased the(Nb, Ti)/Al ratio in the liquid, which led to the precipitation of eutectic(γ + γ’). Laves formed by the sides of η-Ni3(Ti, Nb) and in front of the eutectic( γ + γ’) after Al, Ti were further depleted by the two phases and Cr, Co, Mo were rejected to liquids.

关键词： Superalloy ЭК151 Solidification Eutectic(γ+γ’) η-Ni3(Ti,Nb) Laves

Distribution of Phosphorus and Its Effects on Precipitation Behaviors and Tensile Properties of IN718C Cast Superalloy

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Acta Metallurgica Sinica(English Letters) 2019年第7期32卷 887-899页

作者： An-Wen Zhang Yan Yang Sha Zhang Dong Zhang wei-Hong Zhang da-wei han Feng Qi Yuan-Guo Tan Xin Xin Wen-Ru Sun Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China College of Material Science and Engineering University of Science and Technology of China. Shenyang 110016 China State Key Laboratory of Nickel and Cobalt Resources Comprehensive Utilization Jinchang 737100 China

The effect of phosphorus on the precipitations of γ",γ’ and δ phases and associated tensile properties in IN718C alloy are investigated in this *** is revealed that P atoms are dissolved in the grain interior to a relatively high degree and hence influence the precipitation behaviors in the grain interior and improve the tensile strength of IN718C alloy.γ" and γ’ phases did not precipitate in the alloy without P addition during air cooling,while γ" and γ’ phases precipitated in the grain interior during air cooling in the alloys with P addition,and the amounts of γ" and γ’ phases increased with increasing P ***,the Vickers micro-hardness in the as-cast state increased gradually with increasing P *** double-aging state,the sizes of γ" and γ’ phases in the alloys with P addition were larger than that in the alloy without P addition,while the sizes were invariable when the P content(wt%)was higher than ***,the micro-hardness and tensile strength of IN718C alloy treated by double aging increased first and then kept invariable with increasing P *** precipitations of δ phases both in the grain interior and on grain boundaries were inhibited by P *** inhibitory effect of P on δ phase enhanced gradually with increasing content of P,but the plasticity increased first and then *** is more,the crack tended to propagate into the matrix around the particles(Laves phases and NbC carbides)in the alloys without P addition at the beginning of the tensile fracture,while it tended to propagate along the interfaces between the matrix and those particles in the alloys with P addition,which resulted from the synthetical effect of P on γ" γ’ and δ phases.

关键词： IN718C alloy Phosphorus γ" and γ’ phases δ phase Tensile properties

An improved technique for global daily sunshine duration estimation using satellite imagery

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第9期13卷 717-722页

作者： Muhammad Ali SHAMIM Renji REMESAN da-wei han Naeem EJAZ Ayub ELAHI Department of Civil Engineering University of Engineering and Technology Taxila 47050 Pakistan Department of Geography University of Hull HU6 7RX UK Department of Civil Engineering University of Bristol BS8 ITR UK

This paper presems an improved model for global sunshine duration estimation. The methodology incorporates geostationary satellite images by including snow cover information, sun and satellite angles and a trend correction factor for seasons, for the determination of cloud cover index. The effectiveness of the proposed methodology has been tested using Meteosat geostationary satellite images in the visible band with a temporal resolution of 1 h and spatial resolution of 2.5 km×2.5 km, for the Brue Catchment in the southwest of England. Validation results show a significant improvement in the estimation of global sunshine duration by the proposed method as compared to its predecessor （R2 is improved from 0.68 to 0.83, root mean squared error （RMSE） from 2.37 h/d to 1.19 h/d and the mean biased error （MBE） from 0.21 h/d to 0.08 h/d）. Further studies are needed to test this method in other parts of the world with different climate and geographical conditions.

关键词： Sunshine duration Geostationary satellite Evapotranspiration Solar radiation Remote sensing

From Liquid to Solid‑State Lithium Metal Batteries:Fundamental Issues and Recent Developments

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Nano-Micro Letters 2024年第2期16卷 68-125页

作者： Zhao Zhang wei‑Qiang han School of Materials Science and Engineering Zhejiang UniversityHangzhou 310027People’s Republic of China

The widespread adoption of lithium-ion batteries has been driven by the proliferation of portable electronic devices and electric vehicles,which have increasingly stringent energy density *** metal batteries(LMBs),with their ultralow reduction potential and high theoretical capacity,are widely regarded as the most promising technical pathway for achieving high energy density *** this review,we provide a comprehensive overview of fundamental issues related to high reactivity and migrated interfaces in ***,we propose improved strategies involving interface engineering,3D current collector design,electrolyte optimization,separator modification,application of alloyed anodes,and external field regulation to address these *** utilization of solid-state electrolytes can significantly enhance the safety of LMBs and represents the only viable approach for advancing *** review also encompasses the variation in fundamental issues and design strategies for the transition from liquid to solid *** noteworthy is that the introduction of SSEs will exacerbate differences in electrochemical and mechanical properties at the interface,leading to increased interface inhomogeneity—a critical factor contributing to failure in all-solidstate lithium metal *** on recent research works,this perspective highlights the current status of research on developing high-performance LMBs.

关键词： Lithium metal batteries All-solid-state lithium metal battery Li dendrite Solid electrolyte Interface

General-purpose DNA computation

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Science China Chemistry 2024年第7期67卷 2134-2135页

作者： Junlan Liu da han Institute of Molecular Medicine and Shanghai Key Laboratory for Nucleic Acid Chemistry and Nanomedicine Renji HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai 200127China Zhejiang Cancer Hospital Hangzhou Institute of Medicine(HIM)Chinese Academy of SciencesHangzhou 310022China

Despite the tremendous advancement in the robustness and functionality of DNA-based computing systems throughout the past decade[1-4],reconfiguration of typical DNA computing circuits for diverse tasks is still hindered by the requirement of a priori knowledge about underlying circuit *** addition,the type of algorithms that can be implemented by a DNA integrated circuit(DIC)was limited to a small number,therefore limiting the computing power of DIC[1-4].

关键词： computing knowledge limiting

An unexpected approach to enhance specific surface area and mesopore amount of polyaniline by Zn doping

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Rare Metals 2024年第9期43卷 4585-4594页

作者： Zhi-da Zhu Yu-Zhe han Xiao-Bi Jing School of Mechanical Engineering Yangzhou University School of Chemistry and Chemical Engineering Yangzhou University

Poly-p-anisidine could be easily fabricated via the oxidative polymerization reaction of p-anisidine using H2O2as the green oxidant. It was unexpectedly found that zinc doping could significantly improve the adsorption ability of the material versus heavy metals such as Pb, Cu,Pd, Ag and Hg. Results of nitrogen adsorption–desorption experiments demonstrated that Zn doping could enhance the specific surface area and mesopore amount of the prepared material, which might facilitate its absorption to metals. This work not only provides a novel material for the treatment of heavy metal-polluted water but also leads to a nice mesoporous catalyst support for environment protection and organic synthesis, i.e. the Zn-doped poly-panisidine can be employed as the catalyst support to prepare Cu@PANI-OMe/Zn or Pd@PANI-OMe/Zn for the oxidative degradation reaction of phenol or Suzuki–Miyaura coupling reactions, respectively. It discloses a new strategy for fabricating the mesoporous polyaniline materials with profound application potential.

关键词： Adsorption Catalysis Porous materials Rare metal concentration Surfaces

Disturbance Observer-Based Predictive Tracking Control of Uncertain HOFA Cyber-Physical Systems

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IEEE/CAA Journal of Automatica Sinica 2024年第7期11卷 1711-1713页

作者： da-wei Zhang Guo-Ping Liu IEEE the Center for Control Theory and Guidance Technology Harbin Institute of TechnologyHarbin 150001China the Center for Control Science and Technology Southern University of Science and TechnologyShenzhen 518055China

Dear Editor,In this letter,an output tracking control problem of uncertain cyber-physical systems(CPSs)is considered in the perspective of high-order fully actuated(HOFA)system theory,where a lumped disturbance is use... 详细信息

关键词： Observer Uncertain letter

Effects of nitrogen deposition on the carbon budget and water stress in Central Asia under climate change

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Journal of Arid Land 2024年第8期16卷 1118-1129页

作者： han Qifei XU wei LI Chaofan School of Geographical Sciences Nanjing University of Information Science&TechnologyNanjing 210044China

Atmospheric deposition of nitrogen(N)plays a significant role in shaping the structure and functioning of various terrestrial ecosystems ***,the magnitude of N deposition on grassland ecosystems in Central Asia still remains highly *** this study,a multi-data approach was adopted to analyze the distribution and amplitude of N deposition effects in Central Asia from 1979 to 2014 using a process-based denitrification decomposition(DNDC)*** showed that total vegetation carbon(C)in Central Asia was 0.35(±0.09)Pg C/a and the averaged water stress index(WSI)was 0.20(±0.02)for the whole *** N deposition led to an increase in the vegetation C of 65.56(±83.03)Tg C and slightly decreased water stress in Central *** of this study will expand both our understanding and predictive capacity of C characteristics under future increases in N deposition,and also serve as a valuable reference for decision-making regarding water resources management and climate change mitigation in arid and semi-arid areas globally.

关键词： carbon dynamics climate change grassland ecosystems nitrogen deposition water stress index