材料期刊网

PRECIPITATION BEHAVIOUR AND HARDENING OF B2-ORDERED Ni(Al, Ta)

W.H. Tian and M. Nemoto2(Department of Materials Physics , University of Science and Technology Beijing , Beijing 100083 , China)(Department of Materials Science and Engineering , Faculty of Engineering , Kyushu University , 812 , Fukuoka , Japan)

金属学报(英文版)

Precipitation of Ni2Al in supersaturated NiAl containing Ta and corresponding hardening have been investigated by hardness measurements and by transmission electron microscope observations. Selected area electron diffraction, high resolution electron microscopy and energy dispersive X-ray spectrometer analysis have shown that the Ni2Al with a hexagonal structure precipitates coherently in the B2-NiAl matrix. Ni2Al is an ordered phase with a. unit cell parameter, aNi2All=aNiAl and CNi2Al= aNiAl. The orientation relationship between the Ni2Al precipitate and the B2-NiAl matrix is (0001)Ni2Al (111)NiAl and [1120]Ni2Al[110]NiAl. NiAlhardens appreciably by the precipitation of Ni2Al phase.

关键词: intermetallic compound , null , null , null , null

CORRELATION BETWEEN STRESS COMPONENTS AND STRESS CORROSION CRACKS IN BRASS Lecturer,Department of Materials Physics,University of Science and Technology Beijing,Beijing 100083,China

QIAO Lijie LIU Rui XIAO Jimei University of Science and Technology Beijing , Beijing , China

金属学报(英文版)

The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that under mode Ⅱ loading,stress corrosion cracks nucleated on the site with maximum normal stress component and propagated along the plane perpendieular to the maximum normal stress,under mode Ⅲ loading,the stress corrosion crack was not evident on the 45°plane due to the general corrosion in aqueous solution with high NH_4OH concentra- tion,while stress corroded in aqueous solution with low NH_4OH concentration, numerous cracks with spacings of 10—150μm were found on the 45°plane with maximum normal stress and no stress corrosion cracks was observed on the plane with maximum shear stress.

关键词: stress corrosion cracking , null , null , null

CURRENT STATUS OF HIGH-RESOLUTION ELECTRON-MICROSCOPY AND ITS APPLICATIONS TO MATERIALS SCIENCE AND CONDENSED MATTER PHYSICS

材料科学技术（英文）

The present paper summarizes the current status of high resolution elect;on microscopy ( HREM) and the applications of HREM to materials science and condensed matter physics. This review recounts the latest development of high resolution electron microscope, progress of HREM and the applications of HREM, including the crystal structure determination of microcrystalline materials and characterization of the local structure of the defects and nanostructured materials as well as qualitative and quantitative analysis of the grain boundaries, interfaces and interfacial reactions in the advanced materials by means of HREM in combination with electron diffraction, subnanometer level analysis, image simulation and image processing.

关键词: juxtaposed pentagonal antiprisms;two-dimensional quasicrystal;domain;boundary structures;close-packed phases;nanocrystalline materials;crystal-structure;copper oxidation;initial-stage;translational;symmetry;rotational symmetry

Current Status of High Resolution Electron Microscopy and Its Applications to Materials Science and Condensed Matter Physics

Douxing LI and Hengqiang YE (Laboratory of Atomic imaging of Solids , Institute of Metal Research , Chinese Academy of Sciences , Shenyang , 110015 , China)

材料科学技术（英文）

The present paper summarizes the current status of high resolution electron microscopy (HREM)and the applications of HREM to materials science and condensed matter physics. This review recounts the latest development of high resolution electron microscope, progress of HREM and the applications of HREM, including the crystal structure determination of microcrystalline materials and characterization of the local structure of the defects and nanostructured materials as well as qualitative and quantitative analysis of the grain boundaries, interfaces and interfacial reactions in the advanced materials by means of HREM in combination with electron diffraction,subnanometer level analysis, image simulation and image processing.

关键词:

Oxygen reduction mechanism on copper in a 0.5 M H(2)SO(4)

Electrochimica Acta

The mechanism of the oxygen reduction reaction (ORR) in a naturally aerated stagnant 0.5 M H(2)SO(4) Was studied using electrochemical methods. The cathodic polarization curve showed three different regions; electrochernical impedance spectroscopy (EIS) measurement was used accordingly. The EIS data were analyzed, and the mechanism for the ORR was proposed consequently. The three regions include a limiting current density region with the main transfer of 4e(-) controlled by diffusion (-0.50V < E < -0.40V), a combined kinetic-diffusion region (-0.40V2e(-) transfer due to the adsorption of the anions, and a hump phenomenon region (-0.20V

关键词: Oxygen reduction;Hump phenomenon;Chemical redox;Copper;Electrochemical impedance spectroscopy;sulfuric-acid electrolyte;anodic-dissolution;sulfate-solutions;corrosion;behavior;adsorption;chloride;cu(111);alloy;model

Magnetic and corrosion properties of Fe56Co7M2Mo5Zr10B20 (M = W or Ni) bulk metallic glasses

Journal of Alloys and Compounds

Bulk metallic glasses (BMGs) Fe56Co7M2Zr10Mo5B20 (M = W or Ni) with diameters of 1.5 mm were fabricated by copper mould casting method. There is no significant difference in the glass properties such as glass transition temperature (T-g), onset temperature of crystallization (T-x), supercooled liquid region (Delta T-x), and offset temperature of melting (T-1) except that the onset melting temperature T-m, which are 1454 and 1464 K for the alloy containing W and Ni, respectively. The alloy containing W exhibits some paramagnetic properties while the Ni containing alloy shows fully ferromagnetic. The potentiodynamic polarization experiments show that these alloys have a high corrosion resistance in 3.5 % NaCl solution with strong passivation ability. The alloy containing W shows excellent pitting resistance with a wide passive range (Delta E = 852 mV) and low passive current density in the order of mu A m(-2). Electrochemical impedance spectroscopy (EIS) for either alloy consists only of single capacitive loop. (c) 2005 Elsevier B.V. All rights reserved.

关键词: amorphous materials;casting;bulk metallic glasses;glass forming;ability;high saturation magnetization;p-c alloys;ferromagnetic glasses;amorphous-alloys;1.5 t;hcl;resistance;behavior;system

MICROSTRUCTURE IN LASER FUSED HIGH SPEED STEEL W6Mo5Cr4V2(M2)

LIU Ning CUI Kun Huazhong University of Science and Technology , Wuhan.China DENG Zonggang Hefei University of Technology , Hefei , China CHENG Benpei KONG Jie Institute of Solid State Physics , Academia Sinica , Hefei , China Doctorate student , Department of Mechanical Engineering No.2 , Huazhong University of Science and Technology , Wuhan 430074 , China

金属学报(英文版)

Microstructure of the deepest zone of high speed steel W6Mo5Cr4V2(M2)melt after laser fu-sion was found to be so fine as the ehill zone of a solidified ingot.When narrower chill zoneformed,the long columnar dendrites grow into the melt and then the fine equiaxed cellularstructure appears in upper melt region nearly surface.The substructure of cellular grains anddendrites was observed to consist of martensite and retained austenile,while the carbides asM_6C_■ Cr_7C_3 and MC distributed at their boundaries.It is believed that the highermicrohardness up to HV_(0.1)=865-960 of the laser fused structure of the alloy is due to the oc-currence of martensite.

关键词: High speed steel W6Mo5Cr4V2(M2) , null , null

Department of Metallurgy and Materials Engineering of Chongqing University

YAN Guangting Chongqing University , Sichuan , China.

材料科学技术（英文）

关键词:

Copper corrosion and anodic electrodissolution mechanisms in naturally aerated stagnant 0.5 M H(2)SO(4)

Corrosion Science

Mechanisms of copper corrosion and electrodissolution in naturally aerated, stagnant 0.5 M H(2)SO(4) were investigated by means of electrochemical techniques, compared with deaerated measurements. The role of dissolved oxygen was suggested, and three models were proposed in -0.05 similar to 0.15 V vs. SCE range. Near to corrosion potential, chemical redox between cuprous intermediate and oxygen reduction reaction (ORR) intermediate accelerated copper corrosion, and corrosion rate was controlled by a combined cathodic kinetic-anodic diffusion process. in low and high potential ranges, chemical redox, occurred between cuprous intermediate and oxygen molecule, synergistically accelerated the electrodissolution of copper. (C) 2009 Elsevier Ltd. All rights reserved.

关键词: Copper;Electrochemical impedance spectroscopy (EIS);Corrosion;Electrodissolution;Chemical redox;acidic sulfate-solutions;sulfuric-acid;electrochemical reduction;impedance spectroscopy;oxygen reduction;disk-electrode;reaction;model;dissolution;behavior;iron

EPR investigation of local structure for Mn(H(2)O)(6) (2+) cluster in M(H(2)O)(6) XCl(6): Mn(2+) (M = Zn, Mg, Cd, Ca; X = Pt, Sn) systems at different temperatures

Chemical Physics Letters

A theoretical method for studying the inter-relation between the local structure and EPR spectra is established by diagonalizing the complete energy matrices. For [M(H(2)O)(6)]XCl(6): Mn(2+) (M = Zn, Mg, Cd, Ca; X = Pt, Sn) systems, the calculated results demonstrate that the local structures around the octahedral Mn(2+) centers in the doped systems are very similar despite of the host crystals being different. Furthermore, it is shown that the EPR zero-field parameter D depends simultaneously on the local structure parameters R and h while (a - F) depends mainly on R, whether the doped systems are at liquid-nitrogen temperature or room temperature. (C) 2008 Elsevier B.V. All rights reserved.

关键词: electron-paramagnetic-resonance;single-crystals;spectra;field;ions;spectroscopy;copper(ii);complexes;behavior;mn(ii)