Physics of Metals and Metallography最新文献

Abstract—The study is related to the investigation of hysteretic and magnetostrictive properties of single-layer Fe₁₀Ni₉₀ films and nano-structured [Fe₁₀Ni₉₀/Cu]_p/Fe₁₀Ni₉₀ films, in which magnetostrictive layers are separated with a nonmagnetic interlayer. The magnetostriction effect is shown to depend on the total layer thickness; in this case, the magnetostriction of the [Fe₁₀Ni₉₀/Cu]_p/Fe₁₀Ni₉₀ film structures was found to be higher than that of the single-layer Fe₁₀Ni₉₀ films. The observed peculiarity is associated with weakening the fixing effect of a substrate.

Abstract—The methods of scanning electron microscopy, X-ray diffraction analysis, and microindentation are used to study the effect of alloying with zirconium (within 3 to 6 at %) and complex Zr + Sn and Zr + Sn + Ta additions on the evolution of the structure, phase composition, and properties (effective modulus of elasticity, hardness, and wear-resistance parameters) of quenched biocompatible β-titanium (at %) Ti–26% Nb–3% Zr, Ti–26% Nb–5% Zr, Ti–26% Nb–6% Zr, Ti–26% Nb–3% Zr–1% Sn, and Ti–26% Nb–3% Zr–1% Sn–0.7Ta alloys during aging (at 400°C for 4, 16, and 64 h) after multipass cold rolling with a total degree of strain of 85%. As compared to the quenching, the cold rolling of the studied Ti–Nb–Zr alloys is shown to suppress the occurrence of the β → ω transformation in the course of aging and to favor the acceleration of the decomposition of β solid solution with the formation of nonequilibrium α_l phase in the course of aging. The increase in the zirconium content from 3 to 6 at % in the cold-rolled ternary Ti–26% Nb – х% Zr alloys and introduction of complex Zr + Sn and Zr + Sn + Ta additions to the Ti–26% Nb alloy instead of only zirconium addition hinder the decomposition processes of the β phase during aging; this impacts the intensity of variations of the effective modulus of elasticity and microhardness. The aging of the cold-rolled alloys under study was found to allows us to obtain the higher values of the parameters H/E_r and ({{{{H}^{3}}} mathord{left/ {vphantom {{{{H}^{3}}} {E_{{text{r}}}^{2}}}} right. kern-0em} {E_{{text{r}}}^{2}}}) (Н is the hardness and E_r is the resolved modulus of elasticity) associated with the wear resistance as compared to those for the widely used medical Ti–6Al–4V alloy. The compositions of the alloys and conditions of their treatment are determined, which allow us to obtain the combination of the highest-level properties.

Abstract

Tungsten is currently the most promising material for plasma-facing in FRs. The accumulation of radioactive tritium in tungsten is caused by presence of hydrogen traps in this metal. The paper analyzes the literature data on the parameters of hydrogen traps in tungsten. The review results can predict the accumulation of tritium in tungsten cladding of fusion reactors, ensuring their radiation safety.

Abstract

The results of a study of the resistance to fatigue fracture of the sheets made of the heat-resistant titanium alloys VT18U (Ti–6.5Al–4.3Zr–2.4Sn–0.8Nb–0.7Mo–0.1Si, wt %), VT8 (Ti–6.4Al–3.4Mo–0.3Si, wt %), and VT25U (Ti–6.51Al–3.76Zr–1.71Sn–3.94Mo–0.5W–0.13Si, wt %) have been presented. Fatigue curves have been obtained in the initial state and in the oxidized one after isothermal annealing at a temperature of 560°C for 1000 h in air. It has been established that after annealing, the fatigue resistance of all oxidized alloys in the low-cycle region decreases by an order of magnitude. The fatigue limit of the oxidized alloys VT18U and VT25U does not change and is of about 320 MPa. The high-cycle fatigue limit of the VT8 alloy decreases from 300 MPa in the initial state to 230 MPa in the oxidized state. It has been established that after annealing, the phase composition of an oxide of 250 nm in thickness on the surface of the alloys is different and contains the phases of anatase and rutile for the VT18U and VT25U alloys and contains predominantly rutile for the VT8 alloys, which is why the fatigue limit of the oxidized alloys differs.

Abstract

The surface of an AM60 (Al—5.5, Zn—0.2, Cu—0.009, Fe—0.005, Si—0.1, Ni —0.002, Mn—0.3 wt %, Mg—the rest) magnesium alloy was exposed to a low-energy high-current electron beam. After the irradiation, the content of the β-phase (Mg₁₇Al₁₂) decreases and the aluminum content increases in the alloy surface layer. After the exposure to the electron beam, the corrosion resistance of the alloy in a 1-molar NaCl solution increases significantly compared to the initial state. The physical reason for an increase in the alloy corrosion resistance after exposure to the electron beam is the higher corrosion resistance of the oxide film formed on the alloy surface due to the increased aluminum content.

Abstract

Processes of magnetization in exchange-coupled rapidly quenched nanocrystalline alloys Nd₂(Fe_{1 – x}Co_x)₁₄B, where x = 0, 0.07, 0.2, 0.5, have been studied. Initial magnetization curves and interaction plots δM(H) for various demagnetized states were obtained. Based on comparison of measurement results, influence of the pinning type mechanism on magnetization process in the Nd₂(Fe_{1 – x}Co_x)₁₄B melt-spun ribbons is shown. Using δM(H) plots, a change in intergrain exchange interaction depending on cobalt concentration in rapidly quenched Nd₂(Fe_{1 – x}Co_x)₁₄B nanocrystalline alloys was investigated.

Abstract

A method for solving a self-consistent boundary value problem for the linearized Usadel equation is proposed. The method makes it possible to find the sample-normalized distribution of the superconducting order parameter and the critical temperature as functions of the problem parameters and to solve relatively complex spatially inhomogeneous problems, e.g., superconducting heterostructures containing inhomogeneous magnetic layers. Within this approach, layered structures containing superconducting and domain-split ferromagnetic layers are considered. The theory is compared with experiment for the Fe 20 Å/V 340 Å/Fe 8 Å/Cr/Fe 8 Å system.

Abstract

The paper presents the results of a theoretical and experimental study of the enhancement of the magneto-optical Faraday effect in a magnetoplasmonic nanocomposite, caused by localized plasmon resonance (LPR) in metal nanoparticles. The nanocomposite comprises a three-layer structure of self-assembled gold nanoparticles in a bismuth-substituted iron-garnet matrix. It is shown theoretically and experimentally that the enhancement of the magneto-optical Faraday effect is determined by the action of a magnetic field on the magnetoplasmonic composite as an effective medium as a whole. In this case, in the magnetoplasmonic nanocomposite, the Faraday effect is enhanced at the LPR wavelengths and is slightly weakened in the region of short wavelengths relative to the LPR. It is theoretically shown that the complex gyration index in the off-diagonal terms of the effective permittivity tensor for the magnetoplasmonic composite, in addition to rotation of the polarization plane, leads to the appearance of alternating ellipticity in the vicinity of the plasmon resonance, which is observed in the form of asymmetry of magneto-optical rotation.

Abstract

The temperature dependence of the magnetization of rapidly quenched amorphous Fe–Ni–Si–B alloys was studied by the magnetometry method. The Curie temperatures were determined, and the exchange interaction parameters were calculated: the constants of spin-wave stiffness and exchange stiffness, the root mean-square range of the exchange interaction. The nearest neighboring distance between transition metal atoms was estimated based on the magnetic characteristics.

Abstract

The dynamical properties of sodium closo-borate NaCB₁₁H₁₂ embedded into SiO₂-based nanoporous scaffolds have been studied by nuclear magnetic resonance (NMR) and quasielastic neutron scattering (QENS) over wide temperature ranges. It has been found that a confinement of the closo-borate in nanopores suppresses the order-disorder phase transition, retaining the orientationally disordered phase with high reorientational mobility of the anions and high diffusive mobility of the cations down to low temperatures. This paper is based on the presentation at the RNIKS-2023 conference.