Russian Journal of Non-Ferrous Metals最新文献

In this work, the dependence of the change in structural characteristics and physical and mechanical properties of the Cu–0.6Cr–0.1Zr (wt %) alloy under high-pressure torsion (HPT) on the structural characteristics of the initial state—after quenching with a supersaturated solid solution and after aging with an ensemble of large micron-sized particles and a low concentration of the solid solution—was established. It is shown that, in the case of a quenched state with a supersaturated solid solution, changes in the physical and mechanical properties during the HPT process occur at the first stages of deformation (1–2 revolutions) and subsequently the values of properties stabilize. In the case of the initial state with an extremely low concentration of the solid solution and an ensemble of large particles, a nonmonotonic change in the physical and mechanical properties of the Cu–0.6Cr–0.1Zr alloy is observed, which is closely related to the initial shape, size, and distribution of particles in the material matrix.

In order to produce complex Ti65 alloy structural parts at reduced cost and shorter lead times, samples were fabricated using laser deposition manufacturing (LDM). The microstructure and mechanical properties of specimens produced under 2 kW (low power) and 5 kW (high power) laser settings were compared. Samples fabricated at higher power exhibited better tensile strength and ductility, whereas low-power samples showed a more pronounced tendency to crack. This cracking behavior is attributed to the distinctive chemical composition of Ti65 alloy and the specific laser power settings, which govern the as-deposited microstructure and, consequently, its mechanical properties. In the as-deposited Ti65 alloy, silicides precipitated along α/β interfaces and within the β phase, with larger and more numerous silicides observed in low-power samples. During the LDM process, β-stabilizing elements (W, Zr, Ta, and Nb) tended to concentrate in these silicides, with greater enrichment in the low-power samples, thus causing excessive silicide formation. This increased silicide precipitation, combined with a lower concentration of β-stabilizing elements in the α and β phases, reduced both ductility and strength in the low-power samples. In contrast, high laser power accelerated the dissolution of silicides and enhanced the β-stabilizing elements’ solid solution in the α and β phases, resulting in better formability and improved room-temperature tensile properties.

As traditional hypereutectic Al–Si alloy modifiers, P and Sr can effectively improve the comprehensive mechanical properties of alloys when the alloy is double modified, with the interaction between these composite modifiers affecting the modification effect of the alloy. Therefore, in this study, the transformation of the AlP to Sr₃P₂ phase during P and Sr composite metamorphism was predicted using first-principles calculations based on density functional theory. In addition, Al–15%Si alloys with P and Sr single and composite metamorphism were prepared by gravity casting, and the metamorphism effects were evaluated by microstructure observations and mechanical property testing. The results showed that the Sr₃P₂ phase was more stable than the AlP phase. The experimental results demonstrated that the Sr₃P₂ phase was present in the composite alloy after modification and that the modification effect of primary silicon and eutectic silicon was not ideal. The composite metamorphism improved the comprehensive mechanical properties of the alloy more obviously than single metamorphism, but it did not reach the superposition of single metamorphism mechanical properties, in which the alloy after the addition of Sr and P had the best properties, and the tensile strength, elongation, and hardness reached 301.5 MPa, 0.87%, and 127.8 HV, respectively. Therefore, this method offers an effective strategy for optimizing the modification treatment of hypereutectic Al–Si alloys.

So long as Li-ion batteries (LIBs) have their difficulties, the demand to improve “beyond-lithium” batteries goes beyond the factors of safety and sustainability. With the pressure for renewable energy resources and the enchantingly digitalized current lifestyle, the need for batteries will augment. Therefore, in this article, it has been evaluated the promising alternative alkali metals of “sodium-ion and potassium-ion” batteries. A vast study on H-capture by LiNa[GeO–SiO], LiK[GeO–SiO], LiNa[SnO–SiO], and LiK[SnO–SiO] was carried out including using “DFT” computations at the “CAM–B3LYP–D3/6-311+G(d,p)” level of theory. The hypothesis of the hydrogen adsorption phenomenon was figured out by density distributions of “charge density differences (CDD), total density of states/overlap population density of states (TDOS/OPDOS) and Localized orbital locator (LOL)” for nanoclusters of LiNa[GeO–SiO]–2H₂, LiK[GeO–SiO]–2H₂, LiNa[SnO–SiO]–2H₂, and LiK[SnO–SiO]–2H₂. The oscillation in charge density amounts displays that the electronic densities were mainly placed in the edge of “adsorbate/adsorbent” atoms during the adsorption status. As the benefits of “lithium, sodium or potassium” over “Ge, Sn/Si” possess its higher electron and “hole motion”, permitting “lithium, sodium or potassium” devices to operate at higher frequencies than “Ge, Sn/Si” devices. Among these, “sodium-ion” batteries seem to demonstrate the most agreement in terms of primary competence.

Magnesium-based biodegradable alloys are a promising material for developing self-dissolving surgical implants. Coating their surface is one way to give medical products made of magnesium alloys the necessary corrosion characteristics, as well as increase affinity for bone and accelerate the healing process, by introducing medicines and nutrients into the coating. For magnesium alloys, oxide coatings obtained by oxidizing magnesium or applying oxides of other metals, as well as metal, ceramic, and polymer coatings, are used. In this review, polymer coatings, primarily their effect on the corrosion properties of the material, as well as the features of surface preparation of magnesium alloys before their application, have been considered. Information about the properties of coatings made from various synthetic (polylactide, polycaprolactone, polydopamine) and natural (chitosan) polymers has been provided. Attention to various types of surface treatment, such as mechanical grinding, chemical etching, fluorination, and alkalization, has been paid. For a few polymer coatings, the results of in vitro (on cell cultures) and in vivo (on animals) biocompatibility studies have been presented. Surface pretreatment has been shown to affect greatly such characteristics as coating adhesion and material corrosion resistance.

Composite materials with a porous magnesium matrix and copper reinforcement are promising materials for transport engineering, aviation, energy, and construction. It is possible to form a composite material and a porous structure in a magnesium layer simultaneously in a casting mold by infiltrating liquid magnesium through a layer of granules of water-soluble salts with installed copper reinforcement. To activate the surface and form an adhesive bond when casting composite materials with a magnesium matrix and copper reinforcement, compositions of chloride and chloride-fluoride fluxes, which are widely used in soldering magnesium alloys, have been proposed. On the basis of the studies, compositions of activating fluxes that ensure the spreading of liquid magnesium MG90 and casting alloy ML5 over copper have been established. The effect of the nature of the fluxes and the process temperature on the area of magnesium spreading over the reinforcement has been shown. The adhesion strength of the composite layers when pouring liquid magnesium into a mold with copper reinforcement has been established to be no more than 8 MPa, which is due to the low strength of the Mg₂Cu + MgCu₂ eutectic formed in the transition layer of the composite.

The microstructure, properties and fracture behavior of the coaxial composite all-aluminium wire were studied. Electromagnetically cast aluminium alloys were used as initial materials: Al–0.5 wt % Fe alloy for the core and Al–1.7 wt % Fe alloy for the sleeve. Room temperature co-extrusion was used as a means of producing the composite wire. Annealing at 230°C for 1 h and at 350°C for 3 h were implemented as a matter of studying the thermal stability and obtain maximum ductility, respectively. Values of the electrical conductivity and mechanical strength for the composite wire lay between the values for the Al–0.5 wt % Fe and Al–1.7 wt % Fe alloys, with the exception for the ductility, which is the lowest among all three, especially after heat treatment. The experimental values of the composite wire properties have a good match with ones calculated using the rule of mixtures. It was demonstrated that while electrical conductivity and mechanical strength of the composite wire are determined by the Al–1.7Fe alloy sleeve, the ductility is highly influenced by the Al–0.5Fe alloy core and quality of the interface between constituents.

This study investigates the mechanical, tribological, and thermal properties of Ti6Al4V and SS316L alloys fabricated using the laser powder bed fusion (LPBF) technique. A comparative analysis is conducted, focusing on tensile strength, elongation, and yield strength, alongside microhardness, wear resistance, and the coefficient of friction under varying loading conditions. Ti6Al4V demonstrates superior mechanical performance with an ultimate tensile strength of 965.45 MPa and hardness of 291 HV, compared to SS316L with 506.96 MPa and 232 HV, respectively. However, SS316L exhibits higher elongation at break of 44.77% compared to 15.06% of Ti6Al4V, indicating better ductility. Tribological results reveal significantly lower wear (26.66 µm at 10 N) and coefficient of friction (0.3082 at 10 N) for Ti6Al4V, confirming its superior wear resistance under dry sliding conditions. Maximum wear obtained is 197.16 µm at 15 N in the SS316L sample. Surface topography analysis through optical microscopy images and characterized SEM micrographs reveals microstructural features critical for understanding material behaviour. XRD patterns confirm the phase compositions of both alloys, with distinct peaks showcasing the crystalline nature of the fabricated alloys. Thermal behaviour assessed through TGA-DTA indicates the stability of both alloys up to 1000°C. These findings provide valuable insights into the applicability of LPBF-fabricated Ti6Al4V and SS316L alloys for advanced engineering and orthopaedic applications.

In the presented paper, complex studies of microstructure and phase composition of the alloy before and after electrochemical corrosion tests in solutions of 1 M HCl, 3 M HCl, 1 M H₂SO₄, and 3 M H₂SO₄ have been carried out. The studies showed that the corrosion process in the alloy Ti_49.1Ni_50.9 in the case of electrochemical corrosion took place on all samples and in all solutions in the form of appearance of pittings, as well as with corrosion products when tested in H₂SO₄ solutions with different concentrations; in the case of 3 M HCl, corrosion products were also found on the surface of the samples. A change in character of the microstructure was found in the coarse grained state in 3 M solutions, while no such change was found in the ultrafine grained state.

The effect of heat treatment temperature and holding time on microstructure and corrosion resistance of the cold rolled complex Cu-based alloy was investigated. Increasing holding time under 500°C, the segregation in the alloy was decreased firstly and then increased. An equiaxed grain structure was formed when the temperature was increased to 600°C. When the temperature was researched to 700°C, the equiaxed grain size was further increased and increasing with the increase of the holding time. When the temperature was below 600°C, the corrosion resistant of the alloys were increased with the various of the holding time following the order: 90 > 150 > 30 min. Increasing the temperature to 700°C, the corrosion resistant was decreased with the increase of holding time. The variation of the corrosion resistant of the Cu-based alloys was mainly due to the potential difference which was induced by the variation of distribution of chemical composition and microstructure during the heat treatment.