•D plasma ions impact on BMG leads to D absorption and modification of some properties.•At D ion energy< 120 eV, the amount of D absorbed increases linearly with ion fluence.•At D ion energy> 450 eV, ...the sputtering process dominates.•Plane BMG samples exposed in D plasma are bent due to D trapping in near-surface layer.
Samples of two kinds of bulk metallic glasses (BMG) with different compositions, Zr48Cu36Al8Ag8 and Zr57Cu15.4Al10Ni12.6Nb5, were polished to mirror-like quality and, after measuring the initial reflectance at normal light incidence, were subjected to impact of ions of deuterium or argon plasma with fixed energy. The main attention was paid to phenomenon on deuterium absorption that reveals as the weight gain after every exposure of the samples in deuterium plasma. For a fixed ion energy (in the range<100 eV), the amount of absorbed deuterium increased linearly with increasing of the ion fluence. Bending of the samples was observed when one side of sample was bombarded by deuterium plasma ions. At that, the radius of curvature of samples was decreasing with increasing the amount of trapped deuterium in such a way that its curvature was increasing proportionally to the amount of trapped deuterium. This is an evidence of near-surface distribution of the trapped deuterium. The results demonstrate that D ions within a fluence of ∼2·1025 ions/m2 are initially accumulated in a thin near-surface layer of the samples. Further, they are noted effects of stress relaxation and of deuterium redistribution.
•The structure of a cobalt-boron catalyst has been investigated.•The presence of ferromagnetic clusters in amorphous catalyst was indicated.•The clusters are regularly distributed within the ...core.•The average separation between clusters is 5.8Å.•Cobalt clusters are stabilized by a boron-hydrogen structure formed from BH4− ions.
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The structure of a cobalt-boron catalyst obtained by reduction of cobalt chloride in an aqueous solution of sodium borohydride at ambient temperature has been investigated by TEM HR, XPS, EXAFS and X-ray diffraction method. It was found that nanoparticles of the forming catalyst consisted of a core and a shell. The oxygen-containing compounds (cobalt hydroxide and cobalt borates) mainly reside in the shell. In spite of the amorphous state of the catalyst the EXAFS and X-ray diffraction analysis indicated the presence of ferromagnetic clusters with the shortest CoCo distance of about 2.5Å and coordination number of 2.7 which are regularly distributed within the core with average separations of 5.8Å. The presence in the catalyst of the CoB bonds, a short CoCo distance and the absence of long CoCo distances (4.3 and 4.8Å) as well as the presence of boron bound to hydrogen allows suggestion to be made that stabilization of the cobalt tetramers occurs due to the presence of a boron-hydrogen structure formed by BH4− ions upon the reduction of cobalt chloride. To substantiate the above model of the active phase of the cobalt-boron catalyst the DFT method with a PBE functional in the plane-wave basis has been employed which showed that the ferromagnetic tetramers may exist within a boron-hydrogen matrix isolated from the surrounding medium by an oxygen-containing shell.
We present an overview of the influence of different types of deformation with different stress distributions (rolling, drawing, deformation by hydrostatic compression method of quasi-hydroextrusion ...(QHE) and sequential combination of drawing and QHE at 77 K and 300 K on different physical and mechanical properties of metals and alloys: h.c.p. (Hf, Zr, Ti) and f.c.c. (Al–Mg–Li, 06Х16Н15М3B austenitic steel). The differences in the level of strength, the rate of accumulation of deformation defects, and the anisotropy of their distribution within the bulk of deformed material after drawing, rolling, and QHE are revealed. For the 06Kh16N15M3B steel as an example, we established the reasonability to use a sequence of a combined deformation by drawing with quasi-hydroextrusion for a significant increase in the strength of steel, than that after each individual type of deformation. We revealed the 25%-lowering of the stacking fault energy of titanium, i.e. splitting of dislocations due to the deformation under the uniform compression at 77 K and 300 K. The abnormal increase in shear modulus after the deformation of titanium by hydrostatic compression is revealed. Finally, we discuss the mechanisms of the influences of different types of deformation on mechanical properties of metals and alloys.
The results of experimental and theoretical study of Cr–N films deposition by ion beam-assisted deposition (IBAD) are presented; the structure and electrical–physical properties of the initial stage ...of coating formation are studied. The experiments were carried out with ion energies of 15 and 30 keV and ion current density 25 μA/cm2. The residual gases effect on the film structure is investigated. It is found that oxygen atoms captured from chamber residual atmosphere induces the precipitate Cr2O3 formation on the initial stage of deposition. The radiation-stimulated coalescence of such precipitates occurs in the irradiated films with the increase of condensate thickness. Formation of fine-grained Cr2N precipitates in the irradiated films is observed. The coating thickness for such precipitate formation depends on the ion beam energy. At energies 30 keV fine-grained p Cr2N recipitates are observed for a thickness higher than 70 nm. The performed computer simulation of IBAD demonstrated the good correspondence of calculated and experimental data. It allows to use the computer calculated data to predict the nitrogen distribution in condensed films.
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