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[交流] JMR09年4月关于金属玻璃文章

1 Rate-change instrumented indentation for measuring strain rate sensitivity

Author(s):
D. Pan, M.W. Chen

A rate-change instrumented indentation method is introduced to experimentally characterize the strain rate sensitivity of high strength materials, such as metallic glasses and nanocrystalline metals, which generally possess low rate sensitivity at room temperature. This technique has been validated herein, via self-consistency between rate jump and rate drop measurements, as a viable way to characterize rate dependent deformation behavior and thereby the underlying micromechanisms of plastic flow.

2 Corrosion behavior of the bulk glassy (Fe44.3Cr5Co5Mo12.8Mn11.2C15.8B5.9)98.5Y1.5 alloy

Author(s):
F. Gostin, U. Siegel, C. Mickel, S. Baunack, A. Gebert, L. Schultz

The free corrosion behavior and the anodic passivation ability of the bulk glassy (Fe44.3Cr5Co5Mo12.8Mn11.2C15.8B5.9)98.5Y1.5 alloy were fundamentally analyzed. Electrochemical tests were performed in aqueous solutions with pH values in the interval 0.3–14. Corrosion current densities are below 3 µA/cm2 in the entire studied pH interval; compared with commercial grade steels, for example, X210Cr12 steel, the glassy alloy has lower corrosion rates in acidic electrolytes and higher in basic solutions. The alloy exhibits high dissolution rates upon anodic polarization in acidic environments, but with increasing pH values it tends to form passive layers showing the lowest passive current density at pH 11. The passive layers consist mainly of Fe and Cr oxides. There is a strong variation of the passive layer structure and composition with pH. The protective effect of the grown surface layers is negatively influenced by sulfate ions.

3 Hysteresis loop shift behavior of CoFeSiB amorphous ribbons

Author(s):
J. He, L. Zhou, D.L. Zhao, X.L. Wang

Exchange bias phenomena of amorphous CoFeSiB ribbons have been probed at room temperature. The dramatic loop shift away from zero point occurred when the ribbons were annealed in ambient atmosphere with longitudinal field. The possible crystalline phases grown in our ribbons are discussed based on the grazing incidence diffraction and energy dispersive x-ray spectroscopy. The magnetic domain configuration of ribbon surface was also observed to make clear the dependence of bias behavior on the induced magnetic anisotropy in the ribbon. A simple phenomenological explanation was given to discuss the exchange bias in ribbons.

4 The morphology of organic nanocolumn arrays: Amorphous versus crystalline solids

Author(s):
Jian Zhang, Ingo Salzmann, Peter Schäfer, Martin Oehzelt, Steffen Duhm, Jürgen P. Rabe, Norbert Koch

The morphology of nanocolumns grown by glancing angle deposition is studied for molecular materials forming amorphous and crystalline solids. Amorphous tris(8-hydroxyquinoline)aluminum nanocolumn arrays were obtained at sample rotation speeds varying from 0.3 rpm (revolutions per minute) to 30 rpm. For crystalline pentacene, an array of regular nanocolumns formed at a rotation speed of 3 rpm, while higher and lower rotation speeds led to a wide distribution of column heights and shapes. The incoming molecular flux and the molecular diffusion length on column surfaces, both dependent on rotation speed, were found to govern the resulting morphology of crystalline pentacene nanocolumns.

[ Last edited by hslining on 2009-9-10 at 16:34 ]
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