This study investigates the microstructural response and defect behavior of functionally graded Nb/Zr nanolaminates under proton and helium ion irradiation. Proton fluences ranged from 9.6 × 1016 to 3.5 × 1017 ions/cm2, and helium fluences from 3.4 × 1014 to 6 × 1016 ions/cm2. Transmission electron microscopy and X-ray diffraction confirm the structural stability of the nanolaminate, with no phase transformations observed. Positron annihilation spectroscopy indicates that irradiation does not lead to significant bulk defect accumulation; defect-related changes remain weak and highly localized, with helium producing slightly stronger effects than protons. First-principles calculations show that irradiation-induced atomic displacements are smaller than lattice distortions from intrinsic strain and Nb/Zr interface misfit. Helium interstitials induce stronger local relaxation than hydrogen, though both effects are secondary to interfacial strain fields. These results demonstrate that functionally graded Nb/Zr nanolaminates effectively limit defect accumulation and preserve structural integrity under ion irradiation.

A comparative study of hydrogen absorption on tensile and creep behavior of near-β titanium alloy Ti-5Al-5V-5Mo-1Cr-1Fe (Ti-55511) with fine- and coarse-grained structures was carried out. The formation of fine-grained structure by radial-shear rolling with subsequent aging results in increase of tensile strength of the alloy at room and elevated temperatures as well as creep resistance at 743 K in compare with coarse-grained one. Hydrogenation to 0.1 wt.% leads to an increase in strength and a decrease in ductility of both states of Ti-55511 alloy under tension at room and elevated temperatures. When there is dissolved hydrogen present under creep, the strain rate of steady-state creep increases, and the alloy's time and deformation to failure decrease in both states.

This study aimed to investigate the thermal and structural stability of a functionally graded material (FGM) based on Nb/Zr nanolaminates for potential deployment in fusion reactor environments. The as-fabricated FGM architecture comprised a 2.8 ± 0.4 µm niobium layer, a 1.3 ± 0.1 µm nanolaminate region of alternating Nb and Zr layers (average individual layer thickness: 63 ± 15 nm), a 10 ± 2 µm zirconium layer, and a Zr–1

The diffusion of chromium from the surface was studied in a polycrystalline Zr–1 wt

The development of deformation and fracture in titanium alloy VT22 in the temperature range of 293–823 K is studied in the presence of 0.1 wt.

This paper investigates the effect of thermomechanical treatments, including deformation by radial shear rolling or severe plastic deformation by abc pressing with subsequent aging at 773 K, on the structural-phase state, deformation behavior and mechanical properties of commercial near β titanium alloy VT22 (Ti-5Al-5Mo-5V-1Cr-1Fe). The structure of the alloy after radial shear rolling and subsequent aging consists of transformed β grains with a lamellar α + β structure and primary α-phase particles. Severe plastic deformation of the alloy followed by aging causes the formation of a grain-subgrain α + β structure with an average characteristic size of 0.23 µm. It is found that after the thermomechanical treatments, the strength characteristics of the alloy at room temperature increase by ~40% compared to the as-received alloy. The alloy after radial shear rolling and aging retains a 40-20% higher strength in the temperature range of 293-823 K. The strength of the alloy after severe plastic deformation and aging becomes lower than that of the as-received alloy already at a temperature of 773 K. Analysis of creep parameters at 743 K shows that the creep deformation of the alloy in the state after radial shear rolling and aging occurs by the motion of dislocations (glide + climb). The creep deformation of the alloy in the state after severe plastic deformation and subsequent aging is largely contributed to by grain boundary sliding.

Axonal spheroids are hallmark features of neurodegeneration, forming along degenerating axons and contributing to disease progression. Despite their ubiquity across degenerative etiologies, the dynamics of spheroid disappearance, as well as their interactions with glial cells, remain poorly understood. Here, using an in vivo zebrafish model of peripheral nerve injury, we identified several patterns of spheroid disappearance that are regulated by Schwann cells. These results describe spheroid dynamics across their lifetimes, establish a role for the extra-axonal environment in altering spheroid outcomes, and identify a cellular mechanism whereby spheroid fates are altered.

Zr/Nb nanoscale multilayer coatings (NMCs) were studied after hydrogenation in a gaseous environment at 400 °C. The hydrogen distribution and content were determined by pressure and hydrogenation time. Increasing the pressure from 0.2 to 2 MPa resulted in different hydrogen distribution within the Zr/Nb NMCs, while the concentration remained constant at 0.0150 ± 0.0015 wt. %. The hydrogen concentration increased from 0.0165 ± 0.001 to 0.0370 ± 0.0015 wt. % when the hydrogenation time was extended from 1 to 7 h. The δ-ZrH hydride phase was formed in the Zr layers with Zr crystals reorienting towards the [100] direction. The Nb(110) diffraction reflex shifted towards smaller angles and the interplanar distance in the niobium layers increased, indicating significant lateral compressive stresses. Despite an increase in pressure, the nanohardness and Young’s modulus of the Zr/Nb NMCs remained stable. Increasing the hydrogen concentration to 0.0370 ± 0.0015 wt. % resulted in a 40% increase in nanohardness. At this concentration, the relative values of the Doppler broadening variable energy positron annihilation spectroscopy (S/S0) increased above the initial level, indicating an increase in excess free volume due to hydrogen-induced defects and changes. However, the predominant positron capture center remained intact. The Zr/Nb NMCs with hydrogen content ranging from 0.0150 ± 0.0015 to 0.0180 ± 0.001 wt. % exhibited a decrease in the free volume probed by positrons, as demonstrated by the Doppler broadening variable energy positron annihilation spectroscopy. This was evidenced by opposite changes in S and W (S↓W↑). The microstructural changes are attributed to defect annihilation during hydrogen accumulation near interfaces with the formation of hydrogen–vacancy clusters and hydrides.

The effect of irradiation with a pulsed electron beam on the diffusion of titanium in the polycrystalline Zr-1 wt.% Nb alloy is studied using high-frequency glow discharge optical emission spectrometry. The depth distribution profiles of titanium concentration in the Zr-1 wt.% Nb alloy after isothermal diffusion annealing and annealing under surface irradiation with a pulsed electron beam are determined. It is shown that under simultaneous exposure to temperature and irradiation with a pulsed electron beam, an increase in the coefficient and a decrease in the activation energy of grain boundary diffusion are observed in the near-surface layer of the alloy.

The paper demonstrates the possibility of using the field of permanent magnets for the magnetic isolation of an ion diode and for the ion beam formation. To form a radial magnetic field of a given geometry, ring magnets of complex (special) shape were developed on the base of cylindrical permanent magnets. We also elaborated the design of the anode, magnet frames, and the cathode system of the ion diode. Investigations of the magnetic field parameters were carried out; and experimental data on the accelerating voltage and ion current density were obtained.

The effect of proton irradiation on the structure, phase composition, defect state and nanohardness of Zr/Nb nanoscale multilayer coatings was investigated. Preservation of the Zr/Nb layered structure with 50 and 100 nm thick layers, was observed after irradiation with protons at 1720 keV energy and 3.4 × 1015, 8.6 × 1015 and 3.4 × 1016 ions/cm2 fluences, and the interfaces remained incoherent. In the Zr/Nb nanoscale multilayer coatings with individual layer thicknesses of 10 and 25 nm, there were insignificant fluctuations in interplanar distance, which were influenced by changes in irradiation fluence, and the interfaces were partially destroyed and became semicoherent. Changing irradiation fluence in the investigated ranges led to a decrease in the nanohardness of the Zr/Nb nanoscale multilayer coatings with individual layer thicknesses of 10–50 nm. Variable-energy positron Doppler broadening analysis revealed that these changes are primarily caused by peculiarities of the localization and accumulation of the embedded ions and do not cause a significant increase in the S-parameters of Zr/Nb nanoscale multilayer coatings with a layer thickness less than 100 nm.

Comparative studies of the diffusion and accumulation of hydrogen in the Zr–1 wt.

The effect of pulsed electron beam (PEB) irradiation modes on the structure and defect formation and the mechanical strength in the near-surface layer of a Zr–1 wt

The effect of irradiation with a pulsed electron beam on the diffusion of titanium in the polycrystalline Zr-1 wt.

The effect of helium ion irradiation on the microstructure and properties of composites based on Zr/Nb nanoscale multilayer coatings (NMCs) was studied. X-ray diffraction (XRD), transmission electron microscopy (TEM), and variable-energy Doppler broadening spectroscopy (DBS) were used for the in-depth analysis of defects in the irradiated NMCs. After irradiation of the Zr/Nb NMCs with helium ions at a 10(17) ion/cm(2) dose, the layered structure was generally retained, but the internal stresses in the layers were increased, which caused wave-like distortion in the ion deposition zone. The Zr/Nb NMCs with an individual layer thickness of 25 nm were characterized by the smallest microstress changes, but single blisters were formed in the near-surface region. The microstructure of the Zr/Nb NMCs with a layer thickness of 100 nm exhibited relatively smaller changes upon helium ion irradiation. The prevailing positron-trapping center was the reduced-electron-density area at the interfaces before and after irradiation of the Zr/Nb NMCs regardless of the layer thickness. However, the layer thickness affected the DBS parameter profiles depending on the positron energy, which was probably due to the different localization of implanted ions within the layers or at the interfaces.

The effect of pulsed electron beam (PEB) irradiation modes on the structure formation and properties of the near-surface layer of titanium alloys of the Ti–6Al–4V–H system has been studied. The microhardness, elasticity modulus, friction coefficient, and plasticity (H μ /E) and resistance ( H_^3 / E 2 ) indices have been determined. PEB irradiation in the mode without surface melting is shown to reduce the strength characteristics and the H μ /E and H_^3 / E 2 indices of the near-surface layer of alloys. Because of PEB irradiation in the surface melting mode, a two-phase α + α” lamellar structure with increased H μ /E and H_^3 / E 2 indices is formed in the near-surface layer of alloys 10 μm thick. The effect of the near-surface layer properties on the alloy resistance to deformation under tension and creep has been studied.

Radiation damage is one of the significant factors limiting the operating time of many structural materials working under extreme conditions. One of the promising directions in the development of materials that are resistant to radiation damage and have improved physical and mechanical properties is the creation of nanoscale multilayer coatings (NMCs). The paper is devoted to the experimental comprehension of changes in the defect structure and mechanical properties of nanoscale multilayer coatings (NMCs) with alternating layers of Zr and Nb under irradiation. Series of Zr/Nb NMCs with different thicknesses of individual layers were fabricated by magnetron sputtering and subjected to H+ irradiation. The evolution of structure and phase states, as well as the defect state under proton irradiation, was studied using the methods of high-resolution transmission electron microscopy (HRTEM), X-ray diffraction analysis (XRD), glow discharge optical emission spectroscopy (GDOES), and positron annihilation spectroscopy (PAS). The layer-by-layer analysis of structural defects was carried out by Doppler broadening spectroscopy (DBS) using a variable-energy positron beam. To estimate the binding energy and the energy paths for the hydrogen diffusion in Zr/Nb NMCs, calculations from the first principles were used. When the thickness of individual layers is less than 25 nm, irradiation causes destruction of the interfaces, but there is no significant increase in the defect level, the S parameter (open volume defects amount) before and after irradiation is practically unchanged. After irradiation of NMC Zr/Nb with a thickness of layers 50 and 100 nm, the initial microstructure is retained, and the S parameter is significantly reduced. The GDOES data reveal the irregular H accumulation at the interface caused by significant differences in H diffusion barriers in the bulk of Zr and Nb multilayers as well as near the interface's region.

The characteristics of the high intense pulsed ion beam with energy up to 330 keV have been studied. The ion beam was extracted in the metal drift tube made in form of a cone. It was found that the metal tube provided the beam space charge neutralization up to 90% and increase in the beam current and energy density. The focusing factor of a beam current in the metal tube increased from 4.5 to 13. The mass ratio of ions propagated in the tube and in outer space had been varied. In this case, the proportion of protons in the tube increased from 75.7% to 84.7%.

Studies of the effect of radial-shear rolling and subsequent aging on the structure, mechanical properties and creep of VT22 titanium alloy have been carried out. It is shown that the modification of the structure by radial-shear rolling in the temperature range 1123–1023 K and subsequent aging at a temperature of 773 K makes it possible to increase the strength properties of the VT22 alloy under tension in the temperature range 293–773 K by 40–30% compared to the initial state. Under creep conditions an increase in the creep resistance of the modified structure is observed at stresses below 0.5 of the yield stress.