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Journal of Materials Science & Technology 2015年第12期31卷 1268-1273页

作者： S.guo z.B.Wang K.Lu Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

An aluminide（AlFe and α-（FeAl）） surface layer containing lower-Al was formed on ferritic-martensitic steel p92 by means of surface mechanical attrition treatment（SMAT） combined with a duplex aluminization process at lower temperatures,i.e.a packed aluminization followed by a diffusion annealing treatment below its tempering *** tests indicated that the lower-Al surface layer formed on the SMAT sample is more resistant to cracking and has better adhesion to the substrate in comparison with the Al 5Fe 2 layer formed on the as-received sample after the duplex aluminization *** steam oxidation measurements showed that the oxidation resistance is increased significantly by the lower-Al surface layer due to the formation of a protective（Fe,Cr）Al 2O 4 *** rate constant of oxidation was estimated to decrease from-0.849 mg^2 cm^-4h^-1 of the as-received material to^0.011 mg^2 cm^-4 h^-1 of the AlFe layer at 700 ℃.

关键词： Surface mechanical attrition treatment (SMAT) Ferritic-martensitic steel Lower-temperature aluminization Aluminide Steam oxidation

Correlation between porosity and Fracture Mechanism in High pressure Die Casting of AM60B Alloy

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Journal of Materials Science & Technology 2016年第1期32卷 54-61页

作者： X.Li S.M.Xiong z.guo School of Materials Science and Engineering Tsinghua University State Key Laboratory of Automobile Safety and Energy Tsinghua University

X-ray tomography was used to characterize the porosity in high pressure die casting of AM60B alloy. In situ tensile deformation was performed to observe the change of porosities and their influences on crack initiation, propagation and subsequent fracture of specimen. Results showed that four types of porosi- ties, including gas-shrinkage pore, gas pore, net-shrinkage and island-shrinkage, could be identified according to the formation mechanism and morphology characterization. During tensile deformation, it was shown that the gas-shrinkage pore and net-shrinkage, rather than gas pore or island-shrinkage, were the main sources for crack initiation. In addition, the crack propagated by interconnecting the po- rosities at the cross section with minimum efficient force bearing area. At these locations where externally solidified crystals （ESCs） were present, the crack would propagate along the ESC boundaries in an inter- granular mode, while at these locations without ESCs, the crack would propagate roughly along the direction perpendicular to the tensile stress in a combination of trans-granular and inter-granular modes.

关键词： High pressures die casting AM60B alloy Fracture mechanism porosity

Numerical Modeling and Analysis of Grooved Surface Applied to Film Cooling

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Journal of Bionic Engineering 2011年第4期8卷 464-473页

作者： L. guo z. C. Liu Y. Y. Yan z. W. Han Faculty of Engineering University of Nottingham Nottingham NG7 2RD UK Department of Internal Combustion Engine Jilin University Changchun 130022 P. R. China Key Laboratory of Bionic Engineering （Ministry of Education China） Jilin University Changchun 130022 P. R. China

In order to improve the efficiency of film cooling, numerical investigation was carried out to study the effects of different film-cooled plates on surface heat transfer. Both grooved and non-grooved surfaces were concerned. The modeling was per- formed using Fluent software with the adoption of Shear-Stress Transport （SST） k-ωmodel as the turbulence closure. The coolant was supplied by a single film cooling hole with an inclination angle of 30°. The Mach numbers for the coolant flow and the mainstream flow were fixed at 0 and 0.6, respectively. At three blowing ratios of 0.5, 1.0 and 1.5, the aerodynamic behaviour of the mixing process as well as the heat transfer performance of the film cooling were presented. The numerical results were validated using experimental data extracted from a benchmark test. Good agreements between numerical results and the ex- perimental data were observed. For the film cooling efficiency, it shows that both local and laterally averaged cooling effectiveness can be improved by the non-smooth surface at different blowing ratios. Using the grooved surface, the turbulence intensity upon the plate can be reduced notably, and the mixing between the two flows is weakened due to the reduced turbu lence level. The results indicate that the cooling effectiveness of film cooling can be enhanced by applying the grooved surface.

关键词： film cooling non-smooth surface cooling effectiveness grooved structure blowing ratio

Relationship of Corrosion Behavior Between Single-phase Equiatomic CoCrNi,CoCrNiFe,CoCrNiFeMn Alloys and Their Constituents in NaCl Solution

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Acta Metallurgica Sinica(English Letters) 2021年第11期34卷 1574-1584页

作者： D.p.Wang J.W.Shen z.Chen F.G.Chen p.Y.guo Y.X.Geng Y.X.Wang School of Materials Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China

The composition is a significant issue for corrosion resistance of metallic *** reveal the correlation of corrosion behavior between multiprinciple alloys and their constituents,a series of single-phase equiatomic alloys of CoCrNi,CoCrNiFe and CoCrNiFeMn was *** electrochemical and scanning electron microscope results demonstrated that corrosion resistance of the equiatomic alloys in 0.1 M NaCl solution is located in the range but not the average value of their constituents.X-ray photoelectron spectroscopy analysis indicated that the protective performance of passive film is mainly determined by the constituent with the highest corrosion resistance and the breakdown of passive film is mainly dominated by the elements with the highest corrosion *** findings can guide the materials design of multiprinciple alloys with expected corrosion performance.

关键词： High-entropy alloy Corrosion Constituent X-ray photoelectron spectroscopy(XpS) passive films

EFFECTS OF Ce ON CORROSION RESISTANCE OF Az91D MAGNESIUM ALLOY

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Acta Metallurgica Sinica(English Letters) 2005年第2期18卷 129-136页

作者： z.H.Huang X.F.guo z.M.zhang C.J.Xu SchoolofMaterialsScienceandEngineering Xi＇anUniversityofTechnologyXi＇an710048China

As-cast and corrosive microstructures of Az91D alloy containing various Ce contents were observed by optical microscope (OM). The phase compositions of the alloys before and after the corrosion were analyzed by X-ray diffraction (XRD). Meanwhile, the corrosion resistance of the alloys was tested by weight loss and potentiodynamic polarization curve methods respectively. The results show that rod-like Al4Ce phase is formed in Az91D alloy containing certain Ce content and as-cast microstructures are refined. Az91D-0.7%Ce alloy has good grain refinement effect. The addition of Ce can reduce the corrosion rate and corrosion current density of Az91D alloy and those of Az91D-0.1%Ce alloy reach the minimum, which are 0.35mg/(cm2·d) and 2.761μA/cm2 with 75% and 86% reduction, respectively. The increasing volume fraction and reticular degree of β phase can improve the corrosion resistance of the alloys.

关键词： Az91D magnesium alloy Ce modification microstructure corrosion resistance

RECIpROCATING EXTRUSION OF IN SITU Mg_2Si REINFORCED Mg-Al BASED COMpOSITE

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Acta Metallurgica Sinica(English Letters) 2008年第3期21卷 169-177页

作者： z.M. zhang C.J. Xu X.F. guo S.z. Jia School of Materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

M92Si reinforced Mg-Al based composite with high amount o/silicon was prepared by permanent mould casting, and then extruded by reciprocating extrusion （RE） after the composite was processed by homogenization heat treatment. The effect of RE processing on the morphology and size of M92Si and the mechanical properties of the com- posite were investigated, to develop new ways to refine the M928i phase and improve its shape. The result showed that RE was very useful in refining the M92Si phase. The more the RE processing passes, the better the refining effect would be. Moreover, the uniform distribution of M928i phases would be more in the composite. After the composite was processed by RE for 12 passes, most M92Si phases were equiaxed, with granular diameter below 20 μm, and distributed uniformly in the matrix of the composite. The mechanical properties of the composite could be increased prominently by RE processing, and were much higher than that in the as-cast state. As the temperature rises, the tensile strength is reduced. For the composite RE processed for 12 passes, the tensile strength, yield strength, and elongation are 325.9 Mpa, 211.4 Mpa, and 3.3% at room temperature, whereas, 288.2 Mpa, ,207.7 Mpa, and 7.8%, respectively, at 150℃. In comparison with the properties at room temperature, the tensile strength and yield strength are high and only decrease by 11.6% and 1.8% at 150℃. The M928i reinforced Mg-Al based composite possesses good heat resistance at 150℃. The excellent resistance to effect of heat is attributed to the high melting tempera- ture and good thermal stability of fine Mg2Si phases, which are distributed uniformly in the composite, and effectively hinder the grain boundary gliding and dislocation movement.

关键词： Reciprocating extrusion Magnesium alloy In situ composite Elevated temperature property

Digital Earth: decadal experiences and some thoughts

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International Journal of Digital Earth 2010年第1期3卷 31-46页

作者： H.D.guo z.Liu L.W.zhu Center for Earth Observation and Digital Earth Chinese Academy of SciencesNo.9 Beiyitiao RoadZhongguancunHaidian DistrictBeijing 100190China

The understanding that mankind should reasonably exploit and utilize earth resources and effectively protect the planet on which we live,is now widely ***,effective actions can only be conducted if we better understand and visualize the *** meet this need,digital earth science and technology have been put forward and *** paper introduces the evolution and development process of digital earth,and presents an overview by reviewing and analyzing the 1999 and 2009 Beijing Declaration on Digital Earth,the scientific and commercial digital earth systems,global and regional digital earth research,and some existing platforms of digital earth *** also presents some thoughts about digital earth’s future development.

关键词： Beijing Declaration digital earth system global change

EFFECT OF ANNEALING ON DAMpING CApACITIES OF AS-CAST zA27 ALLOY

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Acta Metallurgica Sinica(English Letters) 2006年第5期19卷 379-384页

作者： z.M. zhang J. C. Wang H.z. Liu X.F. guo School of Materials Science ＆ Engineering Xi＇an University of TechnologyXi＇an 710048 China State Key Laboratory of Solidification processing Northwestern PolytechnicalUniversity Xi＇an 710072 China

zA27 alloy was prepared by casting with permanent mold and then annealed at 250℃ for 1-4h. The damping capaciG of the alloy was measured using a testing apparatus based on the cantilever beam technique. It was found that the as-cast zA27 alloy possesses high damping capacity with the value of 1.3 × 10^4 at 320Hz. After annealed at 250℃ for lh, the damping capacity decreases to 1.1 × 10^-3 and then remains constant even when the annealing time is increased to 4h. The microstructure of the as-cast zA27 alloy consists of large dendrites of Al-rich primaG （x-phases, eutectoid （α ＋ η） and nonequilibrium eutectic phases （α ＋ η ＋ ε）. After annealing at 250℃ for lh, the e phase disappears due to dissolution into the matrix, and the spacing between the flakes of eutectoid increases. The further increase in the annealing time has little effect on the spacing. The damping mechanism of the alloy was discussed considering the thermoelastic damping and defect damping. The value of thermoelastic damping accounts only for 7%-8% in the overall damping in cantilever beam damping measurements and the damping capacity of the zA27 alloy came mainly from defect damping.

关键词： damping capacity zA27 alloy annealing

Enhanced pitting corrosion resistance of a zr-based metallic glass by ultraviolet light irradiation

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Journal of Iron and Steel Research International 2023年第8期30卷 1642-1649页

作者： z.Chen D.p.Wang S.Wang Y.X.Geng Y.X.guo Y.C.Wu z.G.Liu Y.Y.zhang Y.X.Wang School of Materials Science and Engineering Jiangsu University of Science and Technology.Zhenjiang 212003JiangsuChina School of Mechanical Engineering Jiangsu University of Science and TechnologyZhenjiang 212003JiangsuChina

The influence of ultraviolet light irradiation on the pitting corrosion performance of a zr_(2)Ni metallic glass was examined using electrochemical methods and immersion test in 0.05 mol/L NaCl *** the results of potentiostatic polarization,the pitting potential of the ultraviolet light-irradiated sample shifted positively with a value of~300 mV,revealing the enhanced pitting corrosion resistance of the *** corrosion morphology after the immersion test also demonstrated lower degree of corrosion damage and improved pitting resistance of the sample with ultraviolet light irradiation.X-ray photoelectron spectroscopy analysis revealed more zirconium enrichment in the passive film and no chloride ions adsorption for the samples with ultraviolet irradiation,accounting for the suppression of the pit generation and *** findings indicate that ultraviolet light irradiation improves the pitting corrosion resistance of the zr-based metallic glasses,which are promising structural materials to be used in corrosion environments with high ultraviolet irradiation.

关键词： Metallic glass pitting-Corrosion Ultraviolet light irradiation passive film

Microstructural softening induced adiabatic shear banding in Ti-23Nb-0.7Ta-2zr-O gum metal

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Journal of Materials Science & Technology 2020年第19期54卷 31-39页

作者： Silu Liu Y.z.guo z.L.pan X.z.Liao E.J.Lavernia Y.T.zhu Q,M,Wei Yonghao zhao Nano and Heterogeneous Materials Center School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Department of Mechanical Engineering University of North Carolina at CharlotteNC 28223-0001USA School of Aerospace Mechanical and Mechatronic EngineeringThe University of SydneyNSW 2006Australia Department of Materials Science and Engineering University of Californi1IrvineCA 92697USA Department of Materials Science and Engineering North Carolina State UniversityNC 27695USA

Ti-23Nb-0.7Ta-2zr-O gum metal(GM)is an attractive candidate material for applications that require superior mechanical *** our earlier investigation of the GM[1],geometrical softening and the generation of adiabatic shear bands(ASBs)were proposed as primary reasons for the documented anisotropic impact *** the present study,electron backscattered diffraction(EBSD)analysis reveals two different deformed microstructures,i.e.,deformed ultrafine grains(UFGs)and dynamically recrystallized UFGs,formed in the ASBs of GM samples processed by extrusion equal channel angular pressing(ECAp),*** calculation of temperature rise during dynamic compression suggests that the above microstructure differences in the ASBs was originated from their different maximum ASB temperatures(608 K for extruded GM and 1159 K for ECAp-processed GM).Moreover,our calculation on the temperature at the onset of ASBs indicates that microstructural softening is the primary cause for the development of ASBs in both extruded GM(321 K)and ECAp-processed GM(331 K).

关键词： Gum metal Split hopkinson bar Adiabatic shear band Microstructures