The Effect of Irradiation of a Titanium Alloy of the Ti–6Al–4V–Н System with Pulsed Electron Beams on Its Creep

Russian Physics Journal - Comparative studies of the effect of pulsed electron beam irradiation of the Ti–6Al–4V titanium alloys with the contents of hydrogen of 0.002 wt.% (VT6 alloy)...     

Evolution of the Structure and Grain Boundary Ensemble of Nickel during Diffusion Annealing under Conditions a Segregating Impurity (Silver) on Grain Boundaries

Russian Physics Journal - An investigation of the effect of an impurity (silver) segregating on the grain boundaries of nickel on the evolution of the structure and grain-boundary ensemble under...     

Hydrogen Effect on the Defect Structure Formation in the Zr – 1 WT.% Nb Alloy Under Pulsed Electron Beam Irradiation

Russian Physics Journal - Using the methods of X-ray structural analysis and electron and positron spectroscopy, it is found out that an irradiation of the surface of a Zr – 1 wt.% Nb...     

A search for the location of the HF excitation of enhanced ion acoustic and langmuir waves with eiscat and the tromsø heater

In an effort to understand the mechanisms which give rise to the enhanced ion acoustic and Langmuir waves in HF modification experiments, we perform measurements with the EISCAT Tromsø heater and the two incoherent scatter radars to locate the enhancement regions in space. Simultaneous measurements of the enhancements were made with both the VHF (224 MHz) and the UHF (933 MHz) radars, the latter being scanned in the magnetic meridian plane between vertical and field aligned through theSpitze angle. The results show that enhanced bottomside and topside ion acoustic and plasma waves at UHF and VHF are a common phenomena in these data. UHF topside enhanced plasma waves were not observed, possibly due to lack of radar sensitivity. At UHF the enhanced ion waves were strongest when the radar was pointed between theSpitze angle and geomagnetic field aligned direction. The topside features we believe give evidence for the production and propagation of Z-mode waves during this experiment. There is no evidence in these data for the decay of Z-mode waves into Bernstein and lower hybrid waves inside the overdense F layer as we believe to have observed previously.     

A Study of the Structure and Strain Resistance of Low-Alloy 09Mn2Si Steel After Its Helical Rolling Under Static and Dynamic Loading

Russian Physics Journal - The structure and mechanical properties of a 09Mn2Si ductile ferritic-pearlitic steel is studied after helical rolling (HR). It is shown that a fine-grained structure is...     

Evolution of the structural and phase states of a Ti-6Al-4V alloy in forming submicrocrystalline structure with the use of temporary hydrogenation

The special features of the evolution of the structural and phase states of a Ti-6Al-4V alloy in forming submicrocrystalline structure with the use of temporary hydrogen treatment are studied by electron microscopy and x-ray diffraction analysis. Plastic deformation in the α + β two-phase region at 1023 K is found to initiate a complete β → α transformation in a Ti-6Al-4V-H alloy to form an α phase with lattice parameters different from those of the equilibrium α phase. Isothermal annealing at a dehydrogenation temperature of 873 K gives rise to α + β two-phase submicrocrystalline structure with a grain size of ∼ 0.3 μm. The use of nonequilibrium hydrogen release in the deformed Ti-6Al-4V-H alloy exposed to electron beams is shown to result in one-phase submicrocrystalline structure and grain refining. Possible reasons underlying the phase transformations in the alloy under study are discussed. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 86–91, April, 2006.     

Atomistic Modeling of Point Defects and Diffusion in Copper Grain Boundaries

The atomic structure of several symmetrical tilt grain boundaries (GBs) in Cu and their interaction with vacancies and interstitials as well as self-diffusion are studied by molecular statics, molecular dynamics, kinetic Monte Carlo (KMC), and other atomistic simulation methods. Point defect formation energy in the GBs is on average lower than in the lattice but variations from site to site within the GB core are very significant. The formation energies of vacancies and interstitials are close to one another, which makes the defects equally important for GB diffusion. Vacancies show interesting effects such as delocalization and instability at certain GB sites. They move in GBs by simple vacancy-atom exchanges or by long jumps involving several atoms. Interstitial atoms can occupy relatively open positions between atoms, form split dumbbell configurations, or form highly delocalized displacement zones. They diffuse by direct jumps or by the indirect mechanism involving a collective displacement of several atoms. Diffusion coefficients in the GBs have been calculated by KMC simulations using defect jump rates determined within the transition state theory. GB diffusion can be dominated by vacancies or interstitials, depending on the GB structure. The diffusion anisotropy also depends on the GB structure, with diffusion along the tilt axis being either faster or slower than diffusion normal to the tilt axis. In agreement with Borisov's correlation, the activation energy of GB diffusion tends to decrease with the GB energy.     

First On-line beta-NMR on oriented nuclei: magnetic dipole moments of the (nup(1/2))(-1) 1/2(-) ground state in 67Ni and (pip(3/2))(+1) 3/2(-) ground state in 69Cu

The first fully on-line use of the angular distribution of beta emission in detection of NMR of nuclei oriented at low temperatures is reported. The magnetic moments of the single valence particle, intermediate mass, isotopes 67Ni(nup(-1)(1/2);1/2(-)) and 69Cu(pip(1)(3/2);3/2(-)) are measured to be +0.601(5) &mgr;(N) and +2.84(1) &mgr;(N), respectively, revealing only a small deviation from the neutron p(1/2) single-particle value in the former and a large deviation from the proton p(3/2) single-particle value in the latter. Quantitative interpretation is given in terms of core polarization and meson-exchange currents.