•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 first ever search for
α
decays to the first excited state in Yb was performed for six isotopes of hafnium (174, 176, 177, 178, 179, 180) using a high purity Hf sample of natural isotopic ...abundance with a mass of 179.8 g. For
179
Hf, also
α
decay to the ground state of
175
Yb was searched for thanks to the
β
-instability of the daughter nuclide
175
Yb. The measurements were conducted using an ultra-low-background HPGe-detector system located 225 m underground. After 75 days of data taking no decays were detected but lower bounds for the half-lives of the decays were derived on the level of
lim
T
1
/
2
∼
10
15
-
10
18
a. The decay with the shortest half-life based on theoretical calculation is the decay of
174
Hf to the first
2
+
84.3 keV excited level of
170
Yb. The experimental lower bound was found to be
T
1
/
2
≥
3.3
×
10
15
a.
We present characteristics of near-surface layers of d-elements from group IV (titanium, zirconium, and hafnium) after diffusion saturation from a controlled oxygen-containing gas medium (
T
= 750°C, ...τ = 5 h under
P
= 1.33·10
–1
Pa, 1.33·10
–2
Pa, and 1.33·10
–3
Pa). It is shown that a hardened diffusion layer without phase film whose hardness is higher than the hardness of the metal matrix is formed in the order inverse to the order of the affinities for oxygen. The differences in the outward appearance of the surfaces of samples prior to and after heat treatment are demonstrated.
Effect of the chemical composition and crystal structure type of gadolinium complex oxides on their catalytic activity is studied. It is shown that nanocrystalline powders Gd
2
Ti
2
O
7
, Gd
2
Zr
2
O
...7
, and Gd
2
Hf
2
O
7
form highly symmetrical face-centered сubic crystal structures having localized (in Gd
2
Ti
2
O
7
) and delocalized (in Gd
2
Zr
2
O
7
and Gd
2
Hf
2
O
7
) oxygen vacancies. At the same time, low-symmetrical crystal structures are formed in Gd
2
(WO
4
)
3
(the monoclinic structure) and Gd
2
(МоO
4
)
3
(a mixture of monoclinic and rhombic structures). Catalytic runs show that formation of the cubic structure contributes to an increase in the degree of conversion of propane and causes a shift in cracking temperatures to lower values. Formation of this type of nanocrystalline oxides facilitates the dehydrogenation reaction with propylene selectivity up to 80% at temperatures up to 700 К. Formation of the mixture of monoclinic and rhombic structures in Gd
2
(МоO
4
)
3
leads to a shift in the degree of conversion to the catalytic temperature range of 700–900 К, in which the dehydrogenation reaction predominates (80%). In the case of the monoclinic structure of Gd
2
(WO
4
)
3
in the same cracking temperature ranges the process of degradation occurs in parallel; this decreases propylene selectivity to 50% and promotes an increase in the yield of ethylene to 30%.
In the paper on the basis of the analysis of technical indicators and the aggregates used of the applied and introduced forest machinery (multi-operational forest machines) a study was carried out on ...the efficiency of variants in the sorting of logs during the implementation of technological operations in skidding and primary timber transportation under typical natural and production conditions Totemsky Forestry - a branch of the company SAU Forestry of the Vologda region “Vologda Forestry Association” (Vologda region, Russian Federation). As a result of analyzing the ratio of torque and other given dimensional and qualitative indicators, recommendations are given on the use of wheeled picker “Trom 20” for more efficient work in conditions of insufficient bearing capacity of the forest harvesting area soil.
•The improved thermal desorption diagnostics have been developed and tested in the Uragan-2M stellarator.•Using this diagnostics and mass-spectrometric method it was shown that hydrogen can be the ...one of the main gases which desorbs at the temperature of 250-300°C after discharge cleaning in hydrogen atmosphere.•Glow discharge cleaning with Ar plasma leads to Ar noticeable desorption from the stainless steel. Two kinds of desorbed Ar were registered with two different thermal desorption activation energies.
The improved thermal desorption diagnostics has been manufactured, installed and tested in the Uragan-2M (U-2M) stellarator 1-5 for in-situ characterisation a stainless steel (SS) wall outgassing rate and a number of molecular layers of residual gases on its surface in four different positions. The detailed description of this diagnostics, the location of thermal desorption stainless steel probes, the methodology of determining the outgassing rates and the number of molecular layers of residual gases on the probe surfaces are presented. It has been found that the difference between of the data taken from the probes being at different position in the U-2M vacuum chamber lies within the measurement accuracy. Using the present diagnostics together with the mass-spectrometer measurements, some studies were made to investigate the release of gases from the thermal desorption probes before and after radio frequency (RF) or glow discharge (GD) cleaning with hydrogen, helium and argon plasmas. It has been observed that hydrogen sorption by the SS probes surface during the discharge cleaning leads to significant hydrogen desorption even at the temperature of 250-300°C. In this case, hydrogen can be the one of the main gases which desorbs. After U-2M glow discharge cleaning with Ar plasma, the thermal desorption experiment has shown Ar as a significant component which is desorbed from the SS probe surface. Two kinds of desorbed Ar were registered with two different activation energies. The characteristics of the U-2M vacuum system are presented, too, including the block scheme, the list of pumps used to attain the ultimate vacuum, the equipment for measuring the total and partial pressures of residual gases.
The work is devoted to substantiating the use of metallic hafnium as the emitter of the Compton (prompt-response) in-core detector of thermal and resonant neutrons. The main trends in the development ...of nuclear power engineering, which raise the interest in the use of hafnium, are considered. The known data on the behavior of both Compton and β-emission self-powered neutron detectors (SPND) are generalized. The Compton SPND signal formation mechanism for the case of the irradiation by reactor-type fluxes of neutrons and gamma quanta is considered. The paper presents the calculation result of the hafnium burning-out degree for the conditions of WWER and RBMK reactors. The influence of the gamma radiation “sources”, which provide the largest contribution to the electrons production in the detector is considered.
We optimize the conditions of thermochemical treatment of the plates (~ 1 mm) made of GFE-1 hafnium alloy after plastic deformation from the viewpoint of the influence of interstitial elements ...(oxygen) on the solid-solution hardening of the subsurface layers and the fatigue durability of the hafnium specimens subjected to symmetric pure bending. It is shown that the thermochemical treatment (
T
= 850°C, τ = 2 h) performed in the oxygen-containing gaseous atmosphere at
P
= 1.33·10
−2
Pa leads to the formation of a diffusion-hardened subsurface layer on the GFE-1 hafnium specimens, which increases their fatigue life (for the strain amplitude ± ε
a
= 0.6%) as compared with the other levels of pressure of the same medium. The fracture of the specimens of GFE-1 hafnium alloy subjected to the thermochemical treatment in oxygen-containing rarefied gas atmospheres under various pressures is investigated.
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