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Yoji Mine Daisuke Haraguchi Zenji Horita Kazuki Takashima 《Philosophical Magazine Letters》2015,95(5):269-276
We subjected samples of a 304 metastable austenitic stainless steel to high-pressure torsion (HPT) in the temperature range of 303–573 K, (i.e. at different austenite stabilities), to examine their microstructures and mechanical properties. HPT processing at room temperature led to the formation of a lamellar microstructure with austenitic and martensitic phases, of which sizes were characterised by prior austenite grains, whereas HPT processing at moderate temperatures produced nanostructured austenite grains through mechanical twinning. The nanostructured 304 steel with an average grain size of ~70 nm exhibited a fine balance between tensile strength (~1.7 GPa) and reduction of area (~55%). 相似文献
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王帅 《医学与哲学(人文社会医学版)》2010,31(8A):79-81
诺贝尔生理学或医学奖已有百余年历史,其间遗传学获奖项目运用了很多实验材料。它们有的已淡出人们的视线;有的还在使用,并频繁获奖;呈现出此起彼伏、交相更迭的"诺贝尔医学奖实验材料更替现象"。本文旨在探讨与诺贝尔生理学或医学奖相关的遗传学实验材料更替现象,总结其更替规律,并在此基础上预测其选用趋势。 相似文献
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A. M. Mazzone 《Philosophical Magazine Letters》2013,93(5):235-238
Abstract In this work results of a Monte Carlo simulation of the ion penetration in a crystalline silicon target are reported. It is shown that, contrary to the common expectation, channelling is sustained by a non-vanishing divergency of the ion beam for a nominally random orientation of the target. 相似文献
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The effects of crystallization on the electron work function and corrosion resistance of Zr65Al7.5Cu17.5Ni10 amorphous alloys have been studied. The single-phase amorphous alloy exhibits a better corrosion resistance and has a higher work function than the partially and fully crystallized alloys with the same composition. The close relationship between corrosion resistance and work function indicates that the Kelvin probe technique can be a powerful tool for characterizing the corrosion behaviour of amorphous alloy on an electronic level. 相似文献
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P.J. Desre 《Philosophical Magazine Letters》2013,93(6):401-409
The structural complexity of glass-forming alloys, which generally contain more than three components, can lead by partial crystallization during annealing to a dispersion of nanocrystals in an amorphous matrix, giving the material a very high mechanical strength. In the present study, the evolution of the driving force for crystallization is expressed as a function of the composition and the chemical potentials of the components. Application to Zr60Al10Cu30 and Zr60Al10Cu20Pd10 bulk metallic glasses shows that the first crystallization step leads to a metastable equilibrium between nanocrystals of an intermetallic and a percolating amorphous phase. The effects of the number of components and of chemical bonding on the fraction crystallized is analysed and discussed. 相似文献
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The partitioning of the trace element Sn into Cu-rich precipitates in a low-alloy pressure-vessel steel has been characterized using the three-dimensional atom probe (3DAP) technique. This investigation has revealed for the first time that the trace element Sn, present at only 0.007?at.% in the steel, partitions strongly to both small spherical precipitates (<4?nm in diameter) and to large non-spherical precipitates (largest dimension 10–50?nm) during thermal ageing. Sn was also seen to segregate strongly to the precipitate/matrix interface of a large Cu precipitate and particularly in the region where a dislocation appears to intersect the precipitate. The strong attraction of large solute atoms to special sites probably drives the interfacial segregation of Sn. This is consistent with the observation of stronger segregation of Sn to the interface of large precipitates than to the coherent interface of smaller precipitates. 相似文献
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In this letter we employ high-precision Monte Carlo simulations to investigate tracer diffusion kinetics for diffusion via divacancies in the bcc lattice. We utilize the mechanisms originally identified by Mehrer in which the divacancy can move by nearest-neighbour jumps with stable first-nearest-neighbour, second-nearest-neighbour and fourth-nearest-neighbour configurations of the divacancy. The tracer correlation factor and the 'impurity-form' correlation factor were found to be some 4-6% lower than those found by the matrix method. The tracer diffusion data and isotope effect for sodium were revisited in terms of monovacancy and divacancy contributions. The main change is a revision upwards from 0.55 to 0.61 of the j K kinetic factor for divacancies. 相似文献
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T. Mori 《Philosophical Magazine Letters》2013,93(6):453-457
To understand the direct correlation between photodarkening (PD) and photoinduced defect creation (PDC) observed in amorphous chalcogenides, in situ simultaneous measurements of PD and photocurrent (PC) have been performed on amorphous As2Se3 films. The time evolution of PD and PDC during light excitations are empirically described by a stretched exponential function; 1 ??exp[?(t/τ) β ], where τ is the effective response time and β the dispersion parameter. The value of τ for the PDC is very much smaller than that for the PD, suggesting that there is no direct correlation between the two. 相似文献
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It is interesting to investigate the formation of He bubbles in amorphous alloys because point defects do not exist in amorphous materials. In the present study, the microstructural evolution of amorphous Fe79B16Si5 alloy, either irradiated with 5?keV He+ ions or implanted with 150?eV He+ ions without causing displacement damage, and then annealed at a high temperature, was investigated using transmission electron microscopy (TEM). Vacancy-type defects were formed in the amorphous alloy after irradiation with 5?keV He+ ions, and He bubbles formed during annealing the irradiated samples at high temperature. On the other hand, for samples implanted with 150?eV He+ ions, although He atoms are also trapped in the free volume, no He bubbles were observed during annealing the samples even up to 873?K. In conclusion, the formation of He bubbles is related to the formation and migration of vacancy-type defects even in amorphous alloys. 相似文献