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Effect of melt cooling rate on glass transition kinetics and structural relaxation of Vit1 metallic glass

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China Foundry 2021年第2期18卷 118-123页

作者： Wei Zhang Qing-chun Xiang ying-dong Qu Qing-feng Li ying-lei ren Ke-qiang Qiu School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China

The thin ribbons and the bulk cylindrical rods with diameters of 2 mm and 10 mm of the Vit1 metallic glass(MG)were prepared by the single roller melt spinning method and the copper mold injection casting method,*** cooling rates of the samples during melt solidification were *** glass transition behaviors of three groups of MG samples with different solidification cooling rates were studied by differential scanning calorimetry(DSC)at different heating *** effects of melt cooling rate on the glass transition kinetic parameters such as apparent activation energy(E)and fragility parameter(m)of the Vit1 MG were studied using the Kissinger and the Vogel-Fulcher-Tammann(VFT)***,the structural relaxation enthalpy(ΔHrel)of three groups of MG samples was quantitatively analyzed by DSC through multi-step temperature rise and fall *** show that the melt cooling rate(R)has a significant effect on the glass transition kinetics and the structural relaxation of the Vit1 *** R decreases in the order of magnitude,the glass transition temperature(Tg),E,m,andΔHrel of the Vit1 MG gradually ***,in the range of the experimental cooling rates,E,m,andΔHrel all have an approximately linear relationship with lgR.

关键词： glass transition structural relaxation apparent activation energy fragility parameter cooling rate Vit1 metallic glass

Formation and thermal stability of connected hard skeleton structure in ATX525 cast alloys

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China Foundry 2015年第6期12卷 412-417页

作者： Ke-qiang Qiu Hui-han Zhang Yan Re ying-lei ren Rong-de Li School of Materials Science and Engineering Shenyang University of Technology

The formation and the thermal stability of a connected hard skeleton structure(CHSS) in the matrix of Mg-5Al-2Sn-5Ca(ATX525) alloy were investigated by using X-ray diffractometer, scanning electron microscopy, differential scanning calorimeter, creep tester and isothermal treatment method. The results indicated that the CHSS composed of Mg2(Al,Ca) and Al2 Ca intermetallics was formed into a typical eutectic structure and no obvious change occurred when the samples were isothermally treated at 250 °C for 96 h and 350 °C for 72 h, respectively. It became a chained structure when isothermally treated at 450 °C for 48 h. The dissolution and reconstruction processes, however, were observed for the CHSS when the processing temperature was up to 550 °C. The creep life at the stress-temperature condition of 50MPa/200°C for the alloy treated at 450 °C for 48 h was as high as 510 h, and the strain at creep time of 100 h was as low as 0.03%, which indicated that the present alloy has not only a good thermal stability, but also a better heat resistance.

关键词： Mg cast alloy connected hard skeleton structure isothermal treatment thermal stability heat resistance

Glass formation in Fe-Cr-Zr-B-Mo alloys by tuning Nb addition

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China Foundry 2021年第5期18卷 450-456页

作者： Cong-ran Fu Wei Zhang Qing-chun Xiang ying-dong Qu ying-lei ren Bo Yu Ke-qiang Qiu School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China Shenyang Research Institute of Foundry Co.Ltd. Shenyang 110022China

Fe-based bulk metallic glasses(BMGs)with high boron content have potential application as a coating material used in the framework for storing spent nuclear fuels to support their safe long-term *** high glass forming ability(GFA)and large supercooled liquid region are therefore required for such Fe-based BMGs in either the glassy powder fabrication or the subsequent coating *** order to meet these requirements,the influence of Nb content on the GFA of Fe_(57)Cr_(10)Zr_(8)B_(18)Mo_(7-x)Nb_(x)(x=1-5,at.%)alloys was investigated,as Nb has positive roles in GFA and thermal stability of *** results indicate that a fully amorphous phase in the as-cast samples with 3 mm in diameter is obtained for both the Fe_(57)Cr_(10)Zr_(8)B_(18)Mo_(5)Nb_(2) and Fe_(57)Cr_(10)Zr_(8)B_(18)Mo_(4)Nb_(3) *** corresponding supercooled liquid regions of the two BMGs are 78 K and 71 K,*** mechanism for improving their GFA was analyzed based on the principle of metal solidification,the parameters for glass formation and thermal properties of the *** compression strength and Vicker’s hardness of the two BMGs are 1,950 MPa and 1,310 HV,2,062 MPa and 1,180 HV,*** developed BMGs with high B content,good GFA,and very high hardness can be used as coating materials to the framework for spent nuclear fuels.

关键词： amorphous microstructure Nb glass-forming ability coating material

Degradation efficiency of Mg_(65)Cu_(25-x)Ag_(x)Y_(10) nanoporous dealloyed ribbons on pesticide wastewater

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Transactions of Nonferrous Metals Society of China 2022年第5期32卷 1472-1484页

作者： Qing XIA Shi-yao HE Wei ZHANG Qing-chun XIANG ying-dong QU ying-lei ren Ke-qiang QIU School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China

Dealloyed ribbons with a layer of networked nanoporous structure of different pore sizes were fabricated by dealloying the as-spun Mg_(65)Cu_(25-x)Ag_(x)Y_(10)(x=0,5,10,at.%)ribbons in dilute H_(2)SO_(4) solution in order to enhance the degradation efficiency of pesticide *** to the as-spun ribbons,it is found that the dealloyed ribbons with the networked nanoporous structure exhibit higher degradation efficiency due to their large specific surface areas and enough active sites for the degradation *** the average pore sizes of the nanoporous structure and the degradation efficiency of the pesticide wastewater increase with the increase of Ag addition in the dealloyed *** maximum degradation efficiency up to 95.8%is obtained for the Mg_(65)Cu_(15)Ag_(10)Y_(10)dealloyed ribbon under the optimal conditions of pH being 3,the initial cis-cypermethrin concentration being 500 mg/L,and the dosage of dealloyed ribbon being 1.33 g/L.

关键词： networked nanoporous structure MgCu-based amorphous ribbon dealloying cis-cypermethrin wastewater degradation efficiency

Effect of infiltrating time on interfacial reaction and properties of tungsten particles reinforced Zr-based bulk metallic glass composites

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China Foundry 2020年第4期17卷 253-259页

作者： Qing-chun Xiang Zhi-bo Feng Wei Zhang Hong-ding Wang ying-lei ren Ke-qiang Qiu School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China

The tungsten particles reinforced Zr41.2Ti13.8Cu12.5Ni10Be22.5 (Vit 1 alloy) bulk metallic glass composites (BMGCs) were prepared by the melt infiltrating casting method with the infiltrating time of 1, 5 and 10 min, respectively. The changes of interfacial reaction and compression properties of the bulk metallic glass composites with different infiltrating times were studied. Results show that with the increase of infiltrating time, tiny nanocrystals are generated at the interfacial boundary of tungsten particles and the amorphous matrix, and the size of tiny crystals increases with the infiltrating time. When the infiltrating time is 10 min, polygonal crystals with a larger size are also generated within the amorphous matrix. The compressive strength of the composites also increases with the infiltrating time. When the infiltrating time is 10 min, the compressive strength of the composite reaches 2,030 MPa and the compression strain is 44%. The fracture morphology of the composite materials is in a vein-like pattern and the melting phenomenon is found on the fracture surface. In addition, the density of the shear bands during the compressive tests of the composite materials increases with the infiltrating time.

关键词： Zr-based metallic glass infiltrating time interfacial reaction shear bands compressive strength

Fault diagnosis of HVAC system with imbalanced data using multi-scale convolution composite neural network

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Building Simulation 2024年第3期17卷 371-386页

作者： Rouhui Wu Yizhu ren Mengying Tan lei Nie School of Mechanical Engineering Hubei University of TechnologyWuhan430068China Industrial Research Institute of Xiangyang Hubei University of Technology Xiangyang441100China

Accurate fault diagnosis of heating,ventilation,and air conditioning(HVAC)systems is of significant importance for maintaining normal operation,reducing energy consumption,and minimizing maintenance ***,in practical applications,it is challenging to obtain sufficient fault data for HVAC systems,leading to imbalanced data,where the number of fault samples is much smaller than that of normal ***,most existing HVAC system fault diagnosis methods heavily rely on balanced training sets to achieve high fault diagnosis ***,to address this issue,a composite neural network fault diagnosis model is proposed,which combines SMOTETomek,multi-scale one-dimensional convolutional neural networks(M1DCNN),and support vector machine(SVM).This method first utilizes SMOTETomek to augment the minority class samples in the imbalanced dataset,achieving a balanced number of faulty and normal ***,it employs the M1DCNN model to extract feature information from the augmented ***,it replaces the original Softmax classifier with an SVM classifier for classification,thus enhancing the fault diagnosis *** the SMOTETomek-M1DCNN-SVM method,we conducted fault diagnosis validation on both the ASHRAE RP-1043 dataset and experimental dataset with an imbalance ratio of 1:*** results demonstrate the superiority of this approach,providing a novel and promising solution for intelligent building management,with accuracy and F1 scores of 98.45%and 100%for the RP-1043 dataset and experimental dataset,respectively.

关键词： fault diagnosis chiller imbalanced data SMOTETomek multi-scale neural networks

An axisymmetric characteristic model for enhancing prediction of centrifugal compressor characteristics

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Chinese Journal of Aeronautics 2024年第4期37卷 203-215页

作者： Peng ren Xiangjun FANG Zeyu JIAO ying HAN School of Energy and Power Engineering Beihang UniversityBeijing 100191China Guangdong Key Laboratory of Modern Control Technology Institute of Intelligent ManufacturingGuangdong Academy of SciencesGuangzhou 510070China

Rapid and accurate determination of compressor characteristic maps is essential for the initial design of centrifugal compressors in aircraft power systems. The accuracy of existing methodologies, which rely on combinations of loss models, varies significantly depending on the compressor's geometry and operational range. This variance necessitates substantial experimental or Computational Fluid Dynamics(CFD) data for coefficient calibration. To address this challenge, this study presents an axisymmetric characteristic model for compressor performance assessment. This model incorporates the factors of blade angle, meridional passage area, and the radial deflection angle of meridional streamlines of the compressor. These factors are derived from fundamental aerodynamic equations encompassing mass, momentum, and energy conservation of the compressor. In contrast to conventional one-dimensional approaches, the proposed method reduces the number of loss coefficients and more effectively accounts for the impact of geometric alterations on centrifugal compressor properties. Furthermore, the model reduces dependence on experimental and CFD data. Efficacy of the model is validated using experimental data from four distinct types of centrifugal compressors. Correlation analysis reveals that the model's coefficients can be expressed as functions of the ratio of the Reynolds number to the impeller tip speed. This ratio serves as a characteristic parameter for the design and optimization of centrifugal compressors. Consequently, the proposed method offers an efficient and accurate means for the quick computation of centrifugal compressor characteristics. This is of great significance for improving the efficiency of centrifugal compressors and reducing energy consumption.

关键词： Centrifugal compressor Positive problem Characteristic prediction Aerodynamic characteristic Axisymmetric model

Effects of Ti and Be addition on microstructure and mechanical properties of Mg_(58.5)Cu_(30.5)Y_(11) bulk metallic glass

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Transactions of Nonferrous Metals Society of China 2015年第2期25卷 477-482页

作者：邱克强王琳任英磊李荣德沈阳工业大学材料科学与工程学院沈阳110870

Based on the Mg58.5Cu30.5Y11 alloy, 10% Ti, 10% Be and 10% Ti70Be30 （mole fraction） were respectively added to the alloy and samples with a diameter of 3 mm were fabricated by conventional Cu-mold casting method. The phase constituent, thermal stability and microstructure of the alloys were investigated by using X-ray diffraction, differential scanning calorimetry and scanning electron microscopy, respectively. The effects of alloying elements Ti and Be on the microstructure and mechanical properties of *** alloy were discussed. The results show that CuTi phase is distributed in （Mg0.585Cu0.305Y0.11）90Ti10 and （Mg58.5Cu30.5Y11）90（Ti0.7Be0.3）10 alloys, while CuYBe glassy phase containing CuY crystals is embedded in the matrix of （Mg58.5Cu30.5Y11）90Be10 alloy. Under uniaxial compressive loading, the largest compressive fracture strengths for （Mg58.5Cu30.5Y11）90Ti10, （Mg58.5Cu30.5Y11）90Be10 and （Mg58.5Cu30.5Y11）90（Ti0.7Be0.3）10 alloys are 797.6, 952.6 and 1007.8 MPa, respectively, and the strengths are increased by about 17%, 40% and 48% compared with Mg58.5Cu30.5Y11 alloy. The strength reliability for the three alloys is much improved according to the strength distribution region of 10 samples of each alloy.

关键词： Mg-based alloy alloying element Ti Be microstructure strength reliability

Numerical simulations of earthquake rupture induced by pressure perturbation

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Geodesy and Geodynamics 2024年第5期15卷 477-487页

作者： Bingquan ren Caijun Xu Guoyan Jiang lei Yang School of Geodesy and Geomatics Wuhan UniversityWuhan 430079China Key Laboratory of Geospace Environment and Geodesy Ministry of EducationWuhan UniversityWuhan 430079China Key Laboratory of Geophysical Geodesy Ministry of Natural ResourcesWuhan 430079China

The subsurface fluid injection can cause pressure increase within faults,leading to earthquake ***,the factors controlling earthquake rupture due to pressure perturbation remain poorly *** resolve this problem,we simulate the physical processes of earthquake nucleation and rupture on strike-slip faults perturbated by pressure migration based on the slip-weakening *** kinds of factors,including background stress,fluid injection rates,the area of the pressurized region,fault geometry,and fault friction coefficients,are considered in our *** simulation results reveal that the ratio of shear stress to normal stress rather than their absolute values controls the rupture *** the large stress ratios,high injection rates,and large pressurized areas,earthquakes are prone to propagate as runaway ***,faults with large aspect ratios of length to width are also favorable for causing runaway *** contrast,the factors of fault strike,dip angles and friction coefficients have minor influence on rupture behavior.

关键词： Induced seismicity Finite element simulation Rupture mode