The paper considers a special class of structural materials — amorphous alloys. Unlike crystalline alloys, there is no translation symmetry in the arrangement of atoms in amorphous alloys, which have only short-range atomic order. As demonstrated, the primary experimental techniques for confirming the formation of an amorphous structure are X-ray diffraction analysis (XRD) and differential scanning calorimetry (DSC). The effects of the manufacturing processes, structural relaxation, and solidification on the mechanical properties of amorphous alloys are discussed. The differences in the deformation processes between crystalline and amorphous alloys are considered. Deformation of crystalline alloys occurs due to dislocation sliding, whereas amorphous alloys are deformed due to the local rearrangement of atoms that requires significantly higher energies or stresses. As shown, three main types of crystallisation processes can occur, depending on the chemical composition of an amorphous alloy. The first one is polymorphic crystallization, when an amorphous alloy is transformed into a supersaturated solid solution, a metastable or stable crystalline phase without changing its composition. In the second case, two crystalline phases are formed simultaneously due to the eutectic reaction. The third type corresponds to primary crystallization, when stable or metastable phase is formed at the first stage.

There are a significant number of physical and chemical impact methods for the metallic materials during the processes of crystallization, deformation, and heat treatment, leading to the refinement of the structure. However, traditional technologies for the fabrication of metallic materials often result in the coarse-grained structure, as most of them employ processing temperatures, at which the resulting small grains are unstable. From the severe plastic-deformation point of view, traditional rolling has a significant drawback, limiting its use for obtaining the ultrafine-grained structure in materials. Thus, total accumulated deformation is limited during conventional rolling by the multiple decreases in rolled blank thickness. In this regard, in recent years, several specialized rolling methods, which allow eliminating this drawback, were proposed.

The current development of surface treatments, which are aimed at improving the cavitation erosion (CE) resistance of the metal parts working under vibration conditions in liquid environments, is reviewed. The ultrasonic-cavitation test, which is a convenient and express method for evaluating the cavitation resistance of materials, is also considered. The CE resistance of the metal samples is mainly tested using the typical ultrasonic-vibration apparatus according to the ASTM G32-10 test standard. The physical mechanism of the surface cavitation destruction based on the vaporous-bubbles’ formation is described and analysed. This analysis allows for a better understanding of the role of the surface-treatment methods and their parameters on the structure and mechanical properties of the near-surface region, helping to enhance the protection against the destructive cavitation effects. Examples are given regarding the effective methods for improving the surface-properties’ finish of various metal materials, viz., coatings methods including microarc oxidation, arc spraying, high-velocity oxygen-fuel deposition, cold spraying, cathode arc plasma deposition, laser surface alloying, and nitriding. Additionally, the methods of surface modification, such as laser surface treatment, friction stir processing, and tungsten inert-gas welding/dressing, are also concluded to be efficient CE inhibitors.

The present study considers the methods of fabrication and investigation, properties and areas of application of tantalum coatings. These coatings attract attention due to their properties: high wear resistance and corrosion resistance, thermal stability, chemical inertness and biocompatibility. The presented structural, mechanical, tribological, electrical, corrosion, and biological properties make it possible to establish the relationship not only between the technological parameters of obtaining tantalum coatings (argon pressure in the vacuum chamber, substrate temperature, distance between the substrate and the target, etc.) and specific properties, but also to investigate the influence of the structural and phase state on various properties. Currently, tantalum coatings are widely used in microelectronics, medicine, and for corrosion protection. The wide range of information presented in this article enables the prediction of the properties and modelling of the processes of obtaining tantalum coatings with the required characteristics. This, in turn, will make it possible to expand the field of applications of tantalum coatings and deepen knowledge on the relationship between properties.

Alloys based on Ti, Zr, Nb and Ta are the main metal biomedical materials. The proper selection of compositions based on these elements provides the necessary biocompatibility and mechanical compatibility with bone and other tissues of a living organism, as well as high strength with sufficient corrosion resistance in acid and alkaline environments, which are the key criteria in the manufacture of medical implants. The advantages of producing biomedical alloys using powder technology, in comparison with conventional techniques (such as vacuum casting and hot deformation), are discussed. The use of hydrogen as a temporary alloying element in powder technologies of these metals, and the positive effect of hydrogen on reducing residual porosity in the formation of alloys with an enhanced complex of physical and mechanical properties, are considered.

The deformation behaviour of titanium-based alloys and their composites during quasi-static and high-strain-rate compressions is analysed based on the earlier method developed by V.F. Moiseev and his colleagues to analyse stress–strain curves obtained under tension. The present overview approach is employed for the treatment and subsequent analysis of numerous compression curves obtained from quasi-static and high-strain-rate experiments with titanium-based alloys and their composites with varying compositions and initial microstructures. As shown convincingly, the Moiseev’s method can also be successfully applied to analyse the behaviour of alloys under compression. A comparison of the obtained data with structural studies made it possible, in most cases, to identify the mechanisms of deformation and strengthening of titanium alloys in a wide range of compression rates. As found, depending on the type and morphology of the initial structure, deformation and strengthening under compression can be controlled by either α- or β-phase, or both phases simultaneously. The influence of the level of alloying with β-stabilizers and the introduction of strengthening dispersed high-modulus particles into the titanium matrix are considered. As revealed, the strengthening mechanism is often different under quasi-static and dynamic compressions. Moreover, in the case of high-strain-rate compression, the deformation behaviour can differ between the first stage and subsequent stages, which exhibit an oscillating nature. A physical explanation is proposed for the effects discovered during quasi-static and dynamic compressions of the considered titanium materials.

The method of describing the energy spectrum, free energy, and electrical conductivity of disordered crystals based on the use of the Hamiltonian of electrons and phonons is reviewed, analysed, and developed. The electron states of a system are described through the tight-binding model. A simple procedure for calculating the matrix elements of the Hamiltonian within the Wannier’s representation is proposed. Expressions for the Green’s functions, free energy, and electrical conductivity are derived using the diagram method. Using this procedure, the vertex parts of the mass operators of the electron–electron and electron–phonon interactions are renormalized. A set of exact equations is obtained for the spectrum of elementary excitations in a crystal. This enables the performance of numerical calculations on the energy spectrum and the prediction of system properties with predetermined accuracy. Expressions are obtained for the static waves of concentrations, charge and spin densities, which determine the phase state of a disordered crystal. In contrast to other approaches, which account for electron correlations only within the limiting cases of infinitely large and infinitesimal electron densities, this method describes electron correlations in the general case of an arbitrary density. In addition to the theory, the results of a numerical calculation of the energy spectrum of a graphene layer with adsorbed potassium (K) atoms are presented. As established, at the K-atoms’ concentration such that the unit cell includes two carbon (C) atoms and one K atom, the latter being located (adsorbed) on the graphene layer surface 0.286 nm above the C atom, the energy gap is ≅ 0.25 eV. The location of the Fermi level (εF) in the energy spectrum depends on the potassium-atoms’ concentration and is in the energy interval −0.36 Ry ≤ εF ≤ −0.23 Ry.