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Effects of simulated on-fire processing conditions on the microstructure and mechanical performance of Q345R steel

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International Journal of Minerals,Metallurgy and Materials 2016年第1期23卷 49-56页

作者： Yi-chao Peng Hao-hao Xu mai-cang zhang Department of Materials Technology Zhejiang Energy Technology & Research Co.Ltd. Department of Materials Science and Engineering University of Science and Technology Beijing

A series of simulated on-fire processing experiments on Q345R steel plates was conducted, and the plates＇ Brinell hardness, ten- sile strength, and impact energy were tested. Microstructure morphologies were systematically analyzed using a scanning electron micro- scope with the aim of investigating the effect of the steel＇s microstructure on its performance. All examined performance parameters exhib- ited a substantial decrease in the cases of samples heat-treated at temperatures near 700℃. However, although the banded structure decreased with increasing treatment temperature and holding time, it had little effect on the performance decline in fact. Further analysis revealed that pearlite degeneration near 700℃, which was induced by the interaction of both subcritical annealing and conventional spherical annealing, was the primary reason for the degradation behavior. Consequently, some nonlinear mathematical models of different mechanical perform- ances were established to facilitate processing adjustments.

关键词： low alloy steels heat treatment mechanical properties microstructure nonlinear mathematical models

A new insight into rapid oxidation of alloy 925 contaminated by oxide powder

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Rare Metals 2021年第7期40卷 1872-1880页

作者： He Jiang Jian-Xin Dong mai-cang zhang Jiang-Yang Li Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China

Rapid oxidation takes place both in the laboratory and in industrial conditions when alloy 925 is contaminated by oxide powder,and the oxidation rate is much higher than ***,the rapid oxidation behavior and mechanism of alloy 925 were investigated by a series of comparison tests at 1160℃.It is found that the oxide powder produced during the oxidation process is mainly composed of NiCr_(2)O_(4)spinel,accompanied by NiO and NiMoO_(4).The oxide powder plays a triggering role in the rapid oxidation of alloy 925,as NiO has a strong affinity with O.A composition adjustment experiment of alloy 925 shows that rapid oxidation is the synergetic effect of Mo and Cu in the *** and Cu easily combine to form low melting point *** formation and volatilization of MoO_(3)oxide can destroy the completeness of the protective oxide *** MoO_(3)flux can dissolve protective Cr_(2)O_(3)and prevent the repair of the oxide layer and also promote the formation of nonprotective and easy-spall NiCr_(2)O_(4)*** synergetic effect of Cu and Mo in accelerating oxidation should be considered in any nickel-based alloy with a high content of Cu and Mo.

关键词： Rapid oxidation Synergetic effect Nickelbased superalloy

Hot corrosion behavior and mechanism of FGH96 P/M superalloy in molten NaCl–Na_2SO_4 salts

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Rare Metals 2019年第2期38卷 173-180页

作者： He Jiang Jian-Xin Dong mai-cang zhang Lei Zheng Zhi-Hao Yao Materials Science and Engineering University of Science and Technology Beijing

Hot corrosion behavior of FGH96 powder metallurgy(P/M) superalloy in 25 % NaCl + 75 % Na_2SO_4 molten salts at 650, 700, and 750 ℃ was investigated in this paper. The methods of mass loss measurement, X-ray diffraction(XRD), scanning electron microscopy(SEM),and energy-dispersive spectroscopy(EDS) were used *** experimental results show that hot corrosion kinetics follows a square power law at 650 ℃, while a linear one at 700 and 750 ℃. The corrosion layer is detected to be composed of Cr_2O_3, NiO, and Ni2S_3 at each *** cross-sectional morphologies and corresponding elemental maps indicate that the corrosion layer is a stratified structure of oxide and sulfide. The results and analyses confirm that the hot corrosion mechanism of FGH96 P/M superalloy is a cooperate process of oxidation and sulfidation. Furthermore, the relatively higher concentrations of Cr, Co, and Ti provide better corrosion resistance to the attack of S and Cl^-.

关键词： Nickel-based superalloy FGH96 Hot corrosion Molten salts

Mechanism of α-Cr precipitation and crystallographic relationships between α-Cr and δ phases in Inconel 718 alloy after long-time thermal exposure

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International Journal of Minerals,Metallurgy and Materials 2010年第3期17卷 312-317页

作者： Zhong-nan Bi Jian-xin Dong mai-cang zhang Lei Zheng Xi-shan Xie School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

To study the precipitation mechanism of α-Cr phase in Inconel 718 alloy, the samples after long-time aging at 650 and 677℃ were examined by microstructural observations and chemical phase analysis methods. Combining the thermodynamics and kinetics calculation results, α-Cr always precipitates in the vicinity of δ phase, because δ phase rejects Cr into the γ-matrix when growing. The selected area diffraction patterns confirm that the crystallographic relationships of α-Cr with 6 phase are （010）d/（1- 10）*** and [100]d/If 11 ]α-Cr- A graphic model is also presented to show the crystallographic relation between α-Cr and δ phases.

关键词： Inconel 718 precipitation mechanism crystallography thermodynamics kinetics

Constitutive behavior and processing maps of low-expansion GH909 superalloy

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International Journal of Minerals,Metallurgy and Materials 2017年第4期24卷 432-443页

作者： Zhi-hao Yao Shao-cong Wu Jian-xin Dong Qiu-ying Yu mai-cang zhang Guang-wei Han School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China The Fu Foundation School of Engineering and Applied Science Columbia University New York 10027 USA Beijing Institute of Aeronautical Materials Beijing 100095 China Department of High Temperature Materials Research Central Iron and Steel Research Institute Beijing 100081 China

The hot deformation behavior of GH909 superalloy was studied systematically using isothermal hot compression tests in a temperature range of 960 to 1040°C and at strain rates from 0.02 to 10 s−1with a height reduction as large as 70%. The relations considering flow stress, temperature, and strain rate were evaluated via power-law, hyperbolic sine, and exponential constitutive equations under different strain conditions. An exponential equation was found to be the most appropriate for process modeling. The processing maps for the superalloy were constructed for strains of 0.2, 0.4, 0.6, and 0.8 on the basis of the dynamic material model, and a total processing map that includes all the investigated strains was proposed. Metallurgical instabilities in the instability domain mainly located at higher strain rates manifested as adiabatic shear bands and cracking. The stability domain occurred at 960–1040°C and at strain rates less than 0.2 s−1; these conditions are recommended for optimum hot working of GH909 superalloy. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

关键词： Compression testing Constitutive equations Deformation Hot working Microstructural evolution Shear bands Strain Superalloys

Solidification characteristics and hot tearing susceptibility of Ni-based superalloys for turbocharger turbine wheel

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Transactions of Nonferrous Metals Society of China 2014年第9期24卷 2737-2751页

作者：石照夏董建新张麦仓郑磊北京科技大学材料科学与工程学院北京100083

The solidification characteristics and the hot tearing susceptibility were investigated on two Ni-based superalloys for turbocharger turbine wheel, K418 and K419. The segregation behaviors of the alloying elements and the precipitation phases were also studied. The results show that the solidification behavior of K419 alloy is complicated when compared with K418 due to the interdendritic segregation of many kinds of strong interdendritic partitioning elements in the remaining liquid at the final stage of solidification. The segregation of multiple elements in interdendritic liquid results in an extremely low solidus in K419. A long residual liquid stage is found during the solidification of K419, giving rise to reduced cohesion strength of dendrites and increased sensitivity to hot tearing. A hot tearing susceptibility coefficient（HTS） criterion is proposed based on a hot tearing sensitive model. The HTS value of K419 alloy is larger than that of K418 alloy.

关键词： solidification hot tearing susceptibility Ni-based superalloys segregation

Efficient and Stable Perovskite Solar Cells and Modules Enabled by Tailoring Additive Distribution According to the Film Growth Dynamics

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Nano-Micro Letters 2025年第2期17卷 387-400页

作者： Mengen Ma Cuiling zhang Yujiao Ma Weile Li Yao Wang Shaohang Wu Chong Liu Yaohua mai Institute of New Energy Technology College of Physics&Optoelectronic EngineeringJinan UniversityGuangzhou 510632People’s Republic of China Key Laboratory of New Semiconductors and Devices of Guangdong Higher Education Institutes Jinan UniversityGuangzhou 510632People’s Republic of China Guangdong Mellow Energy Co. LimitedYuanming RoadZhuhai 519075GuangdongPeople’s Republic of China

Gas quenching and vacuum quenching process are widely applied to accelerate solvent volatilization to induce nucleation of perovskites in blade-coating *** this work,we found these two pre-crystallization processes lead to different order of crystallization dynamics within the perovskite thin film,resulting in the differences of additive *** then tailor-designed an additive molecule named 1,3-bis(4-methoxyphenyl)thiourea to obtain films with fewer defects and holes at the buried interface,and prepared perovskite solar cells with a certified efficiency of 23.75%.Furthermore,this work also demonstrates an efficiency of 20.18%for the large-area perovskite solar module(PSM)with an aperture area of 60.84 cm^(2).The PSM possesses remarkable continuous operation stability for maximum power point tracking of T_(90)>1000 h in ambient air.

关键词： Gas quenching Additive distribution Buried passivation Blade coating Crystallization dynamics

Relationship Between Grain Boundary Segregation of Antimony and Temper Embrittlement in Titanium-Doped Nickel-Chromium Steel

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Journal of Iron and Steel Research International 2011年第1期18卷 68-72页

作者： ZHENG Lei zhang mai cang DONG Jian-xin MENG Ye School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083China

The antimony segregation at grain boundary was observed and the temper embrittlement in titanium-doped nickel-chromium steel was analyzed. It is concluded that the antimony segregation at grain boundary is nonequilibium and the kinetics of temper embrittlement agrees well with those of nonequilibrium antimony segregation at grain boundary. Besides, the mechanism of nonequilibrium antimony segregation at grain boundary proved to be the most satisfactory one among the existing mechanisms to interpret the antimony induced embrittlement kinetics in the nick- el-chromiunl steel. Based on these, the activation energy and frequency factor of diffusion of antimony vacancy complexes were obtained according to the concept of critical time in nonequilibrium grain boundary segregation theory.

关键词： grain boundary segregation temper embrittlement critical time diffusion activation energy

Preparation of silver nanoparticles through the reduction of straw-extracted lignin and its antibacterial hydrogel

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 504-514页

作者： Lou zhang Shuo Li Fu Tang Jingkai zhang Yuetong Kang Hean zhang Lidong Li State Key Laboratory for Advanced Metals and Materials School of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing 100083China

Silver nanoparticles(Ag NPs)have attracted attention in the field of biomaterials due to their excellent antibacterial ***,the reducing and stabilizing agents used for the chemical reduction of Ag NPs are usually toxic and may cause water *** this work,Ag NPs(31.2 nm in diameter)were prepared using the extract of straw,an agricultural waste,as the reducing and stabilizing *** analysis revealed that the straw extract contained lignin,the structure of which possesses phenolic hydroxyl and methoxy groups that facilitate the reduction of silver salts into Ag *** surfaces of Ag NPs were negatively charged due to the encapsulation of a thin layer of lignin molecules that prevented their *** the prepared Ag NPs were added to the precursor solution of acrylamide,free radical polymerization was triggered without the need for extra heating or light irradiation,resulting in the rapid formation of an Ag NP-polyacrylamide composite *** inhibition zone test proved that the composite hydrogel possessed excellent antibacterial ability due to the presence of Ag *** prepared hydrogel may have potential applications in the fabrication of biomedical materials,such as antibacterial dressings.

关键词： silver nanoparticles hydrogel straw extraction antibacterial