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Dynamic mechanical relaxation behavior of Zr_(35)Hf_(17.5)ti_(5.5)Al_(12.5)Co_(7.5)Ni_(12)Cu_(10)high entropy bulk metallic glass

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Journal of Materials Science & technology 2021年第24期83卷 248-255页

作者： l.t.zhang Y.J.Duan t.Wada H.Kato J.M.Pelletier D.Crespo E.Pineda J.C.Qiao School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an710072China Institute for Materials Research Tohoku UniversitySendai980-8577Japan Universitéde lyon MATEISUMR CNRS5510Bat.B.PascalINSA-LyonF-69621Villeurbanne CedexFrance Department of Physics Barcelona Research Center in Multiscale Science and TechnologyInstitute of Energy TechnologiesUniversitat Politècnica de Catalunya08019BarcelonaSpain

Non-equiatomic high entropy bulk metallic glasses were reported recently and show unique mechanical and physical *** mechanical relaxation behavior of Zr_(35)Hf_(17.5)ti_(5.5)Al_(12.5)Co_(7.5)Ni_(12)Cu_(10)high entropy bulk metallic glass was investigated by dynamic mechanical analysis(DMA)and the mechanical spectra could be well described by the quasi-point defects(QPD)*** to typical metallic glasses,the intensity of theβrelaxation of Zr_(35)Hf_(17.5)ti_(5.5)Al_(12.5)Co_(7.5)Ni_(12)Cu_(10)high entropy bulk metallic glass is lower due to the sluggish *** the same time,the correlation factor is higher than that of conventional metallic glasses and this is ascribed to the high configuration *** parallel,physical aging below the glass transition temperature leads to a decrease of atomic mobility,caused by a decrease of the concentration of defects.

关键词： High entropy bulk metallic glass Mechanical relaxation Quasi-point defects Physical aging

Analysis of the anelastic deformation of high-entropy Pd_(20)Pt_(20)Cu_(20)Ni_(20)P_(20) metallic glass under stress relaxation and recovery

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Journal of Materials Science & technology 2022年第12期107卷 82-91页

作者： Y.J.Duan l.t.zhang t.Wada H.Kato E.Pineda D.Crespo J.M.Pelletier J.C.Qiao School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an 710072China Department of Physics Institute of Energy TechnologiesUniversitat Politècnica de CatalunyaBarcelona 08019Spain Institute for Materials Research Tohoku UniversitySendai 980-8577Japan Universitéde lyon MATEISUMR CNRS5510Bat.B.PascalINSA-LyonF-69621 Villeurbanne CedexFrance

the anelastic deformation behavior of Pd_(20)Pt_(20)Cu_(20)Ni_(20)P_(20) high-entropy metallic glass was probed by monitoring the stress relaxation and recovery processes. the stress relaxation under consecutive strain steps can be described by the Kohlrausch-Williams-Watts(KWW) function. In addition, considering a hierarchy of relaxation processes related to the structural heterogeneity, a constitutive model is proposed in order to describe the whole process of stress relaxation and determine the contribution of different time scales. Moreover, a crossover from stochastic activation to percolation of flow defects with the ultimate strain can be observed during stress relaxation process. the anelastic recovery process after a strain step is studied as a function of the initial strain level and characterized by means of a direct spectrum analysis. the peaks in the recovery time-spectra revealed the evolution of flow defects in Pd_(20)Pt_(20)Cu_(20)Ni_(20)P_(20) high-entropy metallic glass. the understanding of the atomic free-volume zones effect and the anelastic deformation provides important insight into how atomic structural features affect the deformation behavior of high-entropy metallic glasses, and may provide a new avenue into the improvement of their mechanical properties.

关键词： High-entropy metallic glass Stress relaxation Anelastic deformation Flow defects Free-volume zones

MARtENSItE-lIKE PHASE tRANSItIONS DUE tO POlAR REGION StRUCtURE IN DISORDERED FERROElECtRIC CERAMICS

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Acta Metallurgica Sinica(English letters) 1999年第5期12卷 1099-1105页

作者： H.Q.Fan and l.t.zhang State Key lab. of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China

Clear experimental evidence for phase transitions was shown in titanium doped lead magnesium niobate compositional disordered ferroelectric ceramics. One is the diffused phase transition around the temperature of dielectric permittivity maxima, which is often assumed as the characteristics of relaxor ferroelectrics. Another is a first order transition from frequency dispersion relaxor ferroelectrics to normal ferroelectrics, corresponding to a zero field spontaneous polar micro macrodomain switching. According to the x ray diffraction, thermal analysis and transmission electron microscope results, it is pointed out that the relaxor state corresponds to a coexistence of cubic parent phase and nucleating rhombohedral ferroelectric microregion which is similar to a precursor martensite. After the spontaneous relaxor normal ferroelectrics transition, the lower symmetry phase is sure to be a long range rhombohedral phase. thus a dynamic behavior of polar microregions is suggested to explain the phenomena, which is more similar to a stress induced martensitic transformations from cubical stabilized perovskite parent phase.

关键词： lead magnesium niobate relaxor ferroelectric ceramics polar microregion martensitic transformation

Environmental Simulation Experiments of 3D-C/Sic Composites With Different Pyc Interfacial layers

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Environmental Simulation Experiments of 3D-C/Sic Composites ...

StUDY ON C-FIBER-REINFORCED CElSIAN-MAtRIX COMPOSItES

the Fourth International Conference on Physical and Numerical Simulation of Materials (ICPNS’2004)

作者： N.DONG Y.D.XU l.F.CHENG l.t.zhang State Key laboratory of Solidification Northwestern Pohlechnical University. Xi’an 710072 China State Key laboratory of Solidification Northwestern Pohlechnical University. Xi’an 710072 China State Key laboratory of Solidification Northwestern Pohlechnical University. Xi’an 710072 China State Key laboratory of Solidification Northwestern Pohlechnical University. Xi’an 710072 China

＜正＞A series of 3D-C/SiC composites with different pyrolytic carbon （PyC） interfacial layers （about 20-300nm thick） were prepared by chemical vapor infiltration. Simulation experiments at different temperatures were performed by exposing C/SiC specimens in single and coupling gases partial pressure atmospheres, namely, O2, H2O vapor and molten salt （Na+） vapor. It suggested that at intermediate temperature range （about 600-800℃） a dramatic effect of PyC thickness on the weight and strength change of C/SiC was shown, which was mainly influenced by O2 partial pressure;at high temperature range （about 1200-1300℃） the effect was not obvious relatively, which might be influenced by H2O vapor partial pressure;and finally at very high temperature range （＞1500℃） the molten salt vapor was the factor of most possibility affecting the weight change of C/SiC.

关键词： C/SiC Interfacial layer Simulation experiment

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Acta Metallurgica Sinica(English letters) 1999年第5期12卷 1094-1098页

作者： X.W.Yin, l.F.Cheng,l.t.zhang, W.C.Zhou and Y.D.Xu State Key laboratory of Solidification Processing, Northwestern Polytechnical University, Xi′an 710072, China

Strong, tough, and almost fully dense C fiber reinforced celsian matrix composites have been fabricated by impregnation of the fiber tows with the matrix slurry, winding on a drum, drying, stacking the prepreg tapes in the desired orientation, and hot pressing. the monoclinic celsian phase in the matrix was produced in situ, during hot pressing, from amphosous BAS. the unidirectional composites having ≈20 vol% of fibers exhibited graceful failure with extensive fiber pullout in three point bend tests at room temperature. Values of ultimate flexural strength and fracture toughness were 379MPa and 8 3MPa·m 1/2 , respectively.

关键词： barium aluminosilicate celsian composite sol gel carbon fiber

low crude protein formulation with supplemental amino acids for its impacts on intestinal health and growth performance of growing-finishing pigs

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Journal of Animal Science and Biotechnology 2024年第4期15卷 1590-1606页

作者： Marcos Elias Duarte Wanpuech Parnsen Shihai zhang Marvio l.t.Abreu Sung Woo Kim Department of Animal Science North Carolina State UniversityRaleighNC 27695USA

Background low crude protein(CP)formulations with supplemental amino acids(AA)are used to enhance intestinal health,reduce costs,minimize environmental impact,and maintain growth performance of ***,extensive reduction of dietary CP can compromise growth performance due to limited synthesis of non-essential AA and limited availability of bioactive compounds from protein supplements even when AA requirements are ***,implementing a low CP formulation can increase the net energy(NE)content in feeds causing excessive fat *** supplementation of functional AA,coupled with low CP formulation could further enhance intestinal health and glucose metabolism,improving nitrogen utilization,and growth *** experiments were conducted to evaluate the effects of low CP formulations with supplemental AA on the intestinal health and growth performance of growing-finishing *** In Exp.1,90 pigs(19.7±1.1 kg,45 barrows and 45 gilts)were assigned to 3 treatments:CON(18.0%CP,supplementing lys,Met,and thr),lCP(16.0%CP,supplementing lys,Met,thr,trp,and Val),and lCPt(16.1%CP,lCP+0.05%SID trp).In Exp.2,72 pigs(34.2±4.2 kg BW)were assigned to 3 treatments:CON(17.7%CP,meeting the requirements of lys,Met,thr,and trp);lCP(15.0%CP,meeting lys,thr,trp,Met,Val,Ile,and Phe);and VlCP(12.8%CP,meeting lys,thr,trp,Met,Val,Ile,Phe,His,and leu).In Exp.3,72 pigs(54.1±5.9 kg BW)were assigned to 3 treatments and fed experimental diets for 3 phases(grower 2,finishing 1,and finishing 2).treatments were CON(18.0%,13.8%,12.7%CP for 3 phases;meeting lys,Met,thr,and trp);lCP(13.5%,11.4%,10.4%CP for 3 phases;meeting lys,thr,trp,Met,Val,Ile,and Phe);and lCPG(14.1%,12.8%,11.1%CP for 3 phases;lCP+Glu to match SID Glu with CON).All diets had 2.6 Mcal/kg *** In Exp.1,overall,the growth performance did not differ among *** lCPt increased(Plaudin-1 expression in the duodenum and *** lCP and lCPt increased(Pt-1,4F2hc,and B0At exp

关键词： Amino acids Growing-finishing pigs Growth performance Intestinal health low crude protein formulation Net energy

Mechanistic modeling of copper corrosions in data center environments

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Building Simulation 2024年第3期17卷 483-492页

作者： Rui zhang Jianshun zhang Roger Schmidt Jeremy l.Gilbert Department of Mechanical and Aerospace Engineering College of Engineering and Computer ScienceSyracuse UniversitySyracuseNY13244USA Buildings and transportation Science Division Oak Ridge National LaboratoryOak RidgeTN37830USA SyracuseCoE-New York Center of Excellence in Environmental and Energy Systems Syracuse University727 E.Washington StreetSyracuseNY13244USA Department of Bioengineering Clemson UniversityClemson-Medical University of South Carolina Bioengineering ProgramCharlestonSC29425USA

Air-side economizers are increasingly used to take advantage of“free-cooling”in data centers with the intent of reducing the carbon footprint of ***,they can introduce outdoor pollutants to indoor environment of data centers and cause corrosion damage to the information technology *** evaluate the reliability of information technology equipment under various thermal and air-pollution conditions,a mechanistic model based on multi-ion transport and chemical reactions was *** model was used to predict Cu corrosion caused by Cl_(2)-containing pollutant *** also accounted for the effects of temperature(25℃and 28℃),relative humidity(50%,75%,and 95%),and *** also identified higher air temperature as a corrosion barrier and higher relative humidity as a corrosion accelerator,which agreed well with the experimental *** average root mean square error of the prediction was 13.7Å.the model can be used to evaluate the thermal guideline for data centers design and operation when Cl_(2)is present based on pre-established acceptable risk of corrosion in data centers’environment.

关键词： chloride pollutant mixture copper corrosion model data center temperature relative humidity synergistic effect

In situ tEM investigation of electron irradiation and aging-induced high-density nanoprecipitates in an Mg-10Gd-3Y-1Zn-0.5Zr alloy

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Journal of Magnesium and Alloys 2024年第5期12卷 1841-1853页

作者： M.lv H.l.Ge Q.Q.Jin X.H.Shao Y.t.Zhou B.zhang X.l.Ma Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Materials Science and Engineering Research Center Guangxi University of Science and TechnologyLiuzhou 545006China

In-situ electron irradiation and aging are applied to introduce high-density precipitates in an Mg-10Gd-3Y-1Zn-0.5Zr(GWZ1031K,wt.%)alloy to improve the *** results show that the hardness of the Mg alloy after irradiation for 10 h and aging for 9 h at 250℃ is 1.64 GPa,which is approximately 64% higher than that of the samples before being *** is mainly attributed to γ'precipitates on the basal plane after irradiation and the high-density nanoscale β'precipitates on the prismatic plane after aging,which should be closely related to the irradiation-induced homogenous *** latter plays a key role in precipitation *** result paves a way to improve the mechanical properties of metallic materials by tailoring the precipitation through irradiation and aging.

关键词： Mg alloy Electron beam irradiation Hardening Precipitates In-situ tEM

Experimental clearance rate and intraguild predation of jellyfish Cyanea nozakii

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Journal of Oceanology and limnology 2024年第1期42卷 128-140页

作者： Pengpeng WANG Fang zhang Song SUN Shuguo lÜ CAS Key laboratory of Marine Ecology and Environmental Sciences Institute of OceanologyChinese Academy of SciencesQingdao 266071China laboratory for Marine Ecology and Environmental Sciences Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China University of Chinese Academy of Sciences Beijing 100049China Jiaozhou Bay Marine Ecosystem Research Station Chinese Academy of SciencesQingdao 266071China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China Institute of Marine Ecology and Environment Hainan Academy of Environmental SciencesHaikou 570100China

Cyanea nozakii,a common jellyfish distributed in offshore China,has a complex trophic relationship with other zooplankton ***,few studies have reported the predation rates and prey selection patterns of *** medusae on different prey *** is also lacking on the intraguild predation of Aurelia coerulea(another common bloom jellyfish in offshore China)by *** address the knowledge gaps,the clearance rates of *** for different prey items,including copepods(smalllarge>1000μm),fish larvae,and gelatinous prey(hydromedusae,*** ephyrae,and chaetognaths),were *** influence of predator size on the clearance rate was also ***,we examined the intraguild predation of *** on *** *** clearance rates of *** varied widely with prey organisms,being independent of prey *** organisms,except for chaetognaths,were captured with considerably high efficiency,followed by fish larvae and copepods,indicating the preferential prey selection of gelatinous organisms by *** clearance rate increased linearly with the cross-sectional area of *** size in medusae may,to some extents,underpin their capacity to capture more prey by increasing the encounter rate and capture success through *** preyed voraciously on *** in high feeding efficiency,but the clearance rate decreased with increasing ***(as prey)*** phenomenon of intraguild predation suggests a speculative hypothesis of potential population regulation of *** by *** information regarding the feeding ecology of *** reported in this study is important for understanding plankton dynamics in marine ecosystems with extensive occurrences of this jellyfish.

关键词： Scyphomedusae predation rate gelatinous organisms prey selection feeding mechanism