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Effect of corrosion behavior of cast and extruded ZK60 magnesium alloys processed via friction extrusion

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Journal of Magnesium and Alloys 2024年第9期12卷 3553-3573页

作者： A.Sharma V.Beura d.zhang J.darsell S.Niverty V.Prabhakaran N.Overman d.R.Herling V.Joshi K.Solanki School for Engineering of Matter Transportand EnergyArizona State UniversityTempeAZ 85287USA Pacific Northwest National Laboratory RichlandWAUSA

The increasing demand for high-strength,corrosion-resistant magnesium alloys in transportation has led to the development of new processing *** this work,cast and extruded ZK60 magnesium alloys were processed using the innovative solid-phase process,Friction Extrusion(FE).The microstructure was analyzed using Scanning Electron Microscopy(SEM),and Energy dispersive Spectroscopy(EdS),showing a marked reduction in grain size,uniform solute distribution(Zn and Zr),and second phases after FE ***,optical micrographs and Electron Backscatter diffraction(EBSd)were employed to further evaluate the alloy *** corro-sion resistance and electrochemical behavior were analyzed using potentiodynamic polarization,Scanning Electrochemical Cell Impedance Microscopy(SECCIM),and atomic emission spectroelectrochemistry analysis(AESEC).Time evolution surface imaging and post-corrosion microstructures were also analyzed to support the understanding of underlying corrosion *** initiation and propagation in FE-processed samples followed grain boundary patterns,differing from cast and extruded ZK60 *** measurements and in-situ time-dependent optical imaging demonstrated that FE processing enhanced corrosion potential,reduced corrosion current,and increased cathodic ***,FE processing reduced the disparity in pitting potential between cast and extruded samples,resulting in intermediate pitting *** Mg and lower Zn dissolution was observed in the lower anodic currents for FE-processed *** aggravated anodic current cycles,Mg dissolution equalized,but the Zn/Mg dissolution ratio increased for FE-processed extruded samples,suggesting less cathodic activation and better resistance to further pitting.

关键词： Magnesium alloys Corrosion Atomic emission spectroelectrochemistry analysis Scanning electron microscopy

Observational estimation of heat budgets on drifting ice and open water over the Arctic Ocean

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Science China Earth Sciences 2003年第6期46卷 580-591页

作者：卞林根高志球陆龙骅张雅宾 C.Roger X.d.zhang ChineseAcademyofMeteorologicalSciences IARC/Frontier Fairbanks IARC/Frontier Fairbanks

Estimates of the surface heat budget over drifting ice and open water in the Arctic Ocean are made using eddy correlation and flux-profile methods using data obtained from drifting ice and from the R/V Xuelong in the Chinese National Arctic Research Expedition during August 19—24,1999. The results show that the net radiation received by the ice surface is mainly lost through the sensible heat flux and the heat flux due to melting ice, and the latent heat flux making small contribution to the heat balance. However, the heat balance of the open water surface was dominated by the radiative flux whereas the latent and sensible heat fluxes and the oceanic heat flux were greater than those on the sea-ice surface. These results emphasize that thermodynamic processes are quite different between air/open water and air/sea-ice over the Arctic Ocean which is important when considering the effect of sea-air-ice interaction on climate change process dur-ing the summer period.

关键词： Arctic Ocean, drifting ice, open water, turbulence flux, heat balance.

A pre-compensation method of the systematic contouring error for repetitive command paths

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Frontiers of Mechanical Engineering 2015年第4期10卷 367-372页

作者： d. L. zhang Y. H. CHEN Y. P. CHEN State Key Laboratory of digital Manufacturing Equipment andTechnology School of Mechanical Science and Engineering HuazhongUniversity of Science and Technology Wuhan 430074 China

For a repetitive command path, pre-compen- sating the contouring error by modifying the command path is practical. To obtain the pre-compensation value with better accuracy, this paper proposes the use of a back propagation neural network to extract the function of systematic contouring errors. Furthermore, by using the extracted function, the contouring error can be easily pre- compensated. The experiment results verify that the proposed compensation method can effectively reduce contouring errors.

关键词： contouring error pre-compensation motioncontrol system back propagation (BP) neural network

Numerical simulation of the segmentation of the stress state of the Anninghe-Zemuhe-Xiaojiang faults

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Science China Earth Sciences 2016年第12期59卷 384-396页

作者： ZHU AiYu zhang dongNing JIANG ChangSheng Institute of Geophysics China Earthquake Administration

We established a three-dimensional finite element model of the Anninghe-Zemuhe-Xiaojiang faults region using contact surfaces of different sizes to describe the spatial segmentation characteristics of the faults. Our model is based on constraints from GPS observations, models of the crust and upper mantle, precise earthquake locations, the tectonic stress field, the slip rate of the faults, and the rheology of the lithosphere in the Sichuan-Yunnan area. Considering the influence of strong earthquakes since A.d. 1327, we analyzed the main controlling factors of the characteristics of the strong earthquakes and also studied by numerical simulation the possible areas of future earthquake risk and their relationship with tectonic stress. The numerical results showed that the gravitational potential energy of the Qinghai-Tibet Plateau and the interaction of adjacent blocks are the main kinetic factors affecting the characteristics of the tectonic stress distribution. There appears to be some correspondence between the distribution of tectonic stress and the b value; however, we also found that some low b value locations correspond to regions of lower stress. This contradiction may be the result of some comprehensive factors, such as the release of strain energy caused by strong earthquakes.

关键词： Anninghe-Zemuhe-Xiaojiang faults Stress state Gravitational potential energy b value Numerical simulation

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Effect of water injection on the cavitation control:experiments on a NACA66(MOd)hydrofoil

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Acta Mechanica Sinica 2020年第5期36卷 999-1017,I0001页

作者： W.Wang T.Tang Q.d.zhang X.F.Wang Z.Y.An T.H.Tong Z.J.Li School of Energy and Power Engineering Dalian University of TechnologyDalian 116024China Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of EducationDalian University of TechnologyDalian 116024China

The objective of this work is to investigate experimentally controlling cavitating flow over NACA66(MOd)hydrofoils by means of an active water injection along its suction *** continuous water vertically jets out of the chamber inside the hydrofoil through evenly distributed surface *** were carried out in cavitation water *** high-speed visualization technology and the particle image velocimetry(PIV)system to study the sheetlcloud cavity *** studied the effects of this active control on cavity evolution with four kinds of jet flow at two different jet *** analyzed the effect of water injection on the mechanism of the cavitating flow *** results were all compared with that for the original hydrofoil without jet and show that the active jet can effectively suppress the sheet/cloud cavitation characterized by shrinking the attached cavity size and breaking the large-scaled cloud sheding vortex cavity into small-scaled *** optimum effectiveness of cavitation suppression is affected by the jet flow rates and jet *** water injection at flow rate coefficient 0.0245 with the jet position of 0.45C reduces the maximum sheet cavity length by 79.4%and the cavity shedding is diminished completely,which gives the most superior effect of sheet cavitation *** jet blocks the re-entrant jet moving upstream and weakens the power of re-entrant jet and thus restrains the cavitation development effectively and stabilizes the flow field.

关键词： Cavitation active control Sheet/cloud cavitation.Water injection Re-entrant jet

A Pipelined Window Implementation of Multilayer Networks with Time-Sequence Input Patterns for Speech Recognition

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A Pipelined Window Implementation of Multilayer Networks wit...

THE INTERFACE OF TERNARY-BORIdE-BASEd HARd CLAddING MATERIAL

第五届全国人机语音通讯学术会议

作者： david d．zhang department of Computer Science City University of Hong Kong Kowloon Hong Kong

＜正＞Numerous studies have demonstrated effectiveness of the multilayer networks with time sequences as inputs to the networks. A common design approach used in these neural networks（NN） is incorporation of short delays, of temporal integration, or of recurrent connections. Spectral inputs are applied to input nodes sequentially, one frame at a time, and their corresponding input matrix can be formed. The NNs can thus be integrated into real time speech recognizer because only short delays are used.

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来源： cnki会议评论

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Acta Metallurgica Sinica(English Letters) 2004年第1期17卷 47-50页

作者： Y.G.Wang Z.Q.Li d.zhang State Key Laboratory of Metal Matrix Composites Shanghai Jiaotong UniversityShanghai 200030 ChinaMechanical Engineering DepartmentShandong University Jinan 250061 ChinaState Key Laboratory of Metal Matrix CompositesShanghai Jiaotong UniversityShanghai 200030China

The interfacial microstructure of ternary-boride-based hard cladding material (YF-2) has been studied using scanning electron microanalyser (SEM), X-ray diffraction (XRd) and energy disperse spectroscopy (EdS). Results show that there are chemical reactions and elements diffusion in the interfacial zone, which make the interface bonding well and bonding strength ideal at the interface. The results gotten by studying of crack produced by Vickers indentation technique in the interfacial zone show that it is difficult to produce crack in the interface, the crack length in the cladding layer is longer than that to the interface, the crack which propagate to the interface stops at the interface rather than propagates along the interface. This suggests negligible residual stresses have developed because of thermal expansion mismatch. The bonding strength of the interface is 550MPa, which has been gotten by cutting test. The result gotten by analyzing the fracture surface shows that the fracture occurs at the side of cladding layer, which confirms that the bonding strength at the interface is higher than that in the cladding layer.

关键词： ternary boride cladding material interface micro structure

Synchronous optimization of strengths, ductility and corrosion resistances of bulk nanocrystalline 304 stainless steel

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Journal of Materials Science & Technology 2020年第2期37卷 161-172页

作者： S.G.Wang M.Sun S.Y.Liu X.Liu Y.H.Xu C.B.Gong K.Long Z.d.zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

Structural materials usually suffer from several attacks during their service,such as tension,fatigue and *** is necessary to synchronously improve these properties for their lightweight and longlifetime,but corrosion resistance and ductility are generally inverse correlation with strength,it is very difficult to simultaneously optimize all three ***,bulk nanocrystalline 304 stainless steel(BN-304SS)produced by severe rolling technology possessed the larger yield and ultimate tensile strengths with sufficient elongation(>40%)during tensile test,the larger saturation stress and longer lifetime during low-cycle fatigue,the enhanced uniform and pitting corrosion resistances during fiveday immersion test in 6 mol/L HCl,the lowered stress corrosion cracking(SCC)susceptibility with larger yield(~2.40 GPa)and ultimate tensile(~2.66 GPa)strengths,and enough elongation(>30%)during stress corrosion in comparison with conventional polycrystalline 304 stainless steel(CP-304 SS)*** uniform and pitting corrosion resistances of fractured BN-304SS were enhanced in comprsion with those of fractured CP-304 SS during seven-day immersion test in 1 mol/L *** results demonstrated the strengths,ductility and corrosion resistances of BN-304SS can be simultaneously optimized by severe rolling *** improved results of BN-304SS in different disciplines were understood by its valence electron configurations rather than traditional microstructural parameters.

关键词： Stainless steel Pitting corrosion Stress corrosion Tensile properties Low-cycle fatigue Severe rolling technology

Magnetization reversal of antiferromagnetically coupled perpendicular anisotropy films driven by current

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Journal of Materials Science & Technology 2018年第5期34卷 832-835页

作者： X.T.Zhao Y.Q.Zhao W.Liu Z.M.dai T.T.Wang X.G.Zhao Z.d.zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

By inserting an ultrathin Pt layer at Co/Ru interface,we established antiferromagnetic coupling with outof-plane magnetization in Co/Ru/Co film stacks fabricated by *** achieve configuration suitable for free layer,the magnetic properties of the stacks have been investigated by changing the thickness of Co,Ru and Pt layers using an orthogonal wedges *** is found that magnetic properties for upper Co layer thinner than 0.5 nm are sensitive to little change in Ru *** continuity of upper Co layer by slightly increasing the thickness can effectively increase the squareness of minor *** switching magnetization of synthetic antiferromagnetic（SAF） structure is achieved by dC current under an in-plane static magnetic field of ± 500 *** structure is very promising for free layer in spintronic application.

关键词： Magnetic materials Multilayer structure Wedge Exchange coupling Antiferromagnetic