The lithium-ion industry is experiencing a rapidly growing demand for compounds containing lithium. Spodumene is one of the primary industrial minerals used in the production of this metal. It exists in three polymorphic forms. In its natural state, it is known as α-spodumene, which possesses a high resistance to chemical attack due to its compact structure containing silicon and aluminum oxides. When subjected to microwave radiation, α-spodumene undergoes a transformation, first becoming the γ form and then transitioning to the β form. It is known that the β form can be chemically treated to extract lithium. In light of this, microwave exposure was applied to α-spodumene with the aim of decrepitation, followed by sulfuric acid decomposition of the mineral. The mineral was crushed into different sizes (1.0, 0.5, and 0.25 mm). Temperature changes, induced by both conventional and microwave heating, were analyzed. The heating process was continued for samples of various sizes until a temperature of 1200 °C was reached. Sulfation of calcined samples was carried out for 60 minutes at a temperature of 250 °C. After cooling to 22 °C, distilled water was added and mixed for 120 minutes in closed leaching vessels. To determine the recovery of valuable and associated components, leach cakes and the liquid phase were analyzed using inductively coupled plasma atomic emission spectrometry. Based on the analysis of experimental results, the feasibility of using microwave radiation for decrepitation of spodumene to extract lithium is confirmed. The influence of particle size on phase transformations and, consequently, the degree of lithium extraction from spodumene was investigated. It was found that the recovery of lithium during the microwave action and leaching process for particles smaller than 0.25 mm reached 96.82 %. Microwave heating resulted in lower recovery rates of “harmful” components, such as iron, sodium, and calcium, in the leaching process, leading to a higher purity of the resulting product.

Aluminum ranks as the fourth most conductive metal, trailing behind silver, copper, and gold in electrical conductivity. Annealed aluminum demonstrates an approximate 62 % conductivity of the International IACS compared to annealed standard copper, which registers 100 % IACS at t = 20 °C. Because to its low specific gravity, aluminum exhibits twice the conductivity per unit mass compared to copper, showcasing its potential economic advantage as a material for conducting electricity. For equal conductivity (in terms of length), an aluminum conductor exhibits a cross-sectional area 60 % larger than that of copper, while weighing only 48 % of copper's mass. However, the widespread use of aluminum as a conductor in electrical engineering is often challenging and sometimes unfeasible due to its inherent low mechanical strength. Enhancing this crucial property is achievable through the addition of dopants. However, this approach tends to elevate mechanical strength at the cost of noticeable reductions in electrical conductivity. This study investigates the impact of lithium addition on the anodic behavior of an A5 aluminum conductor alloy, specifically modified with 0.1 wt.% Ti (AlTi0.1 alloy), within a NaCl electrolyte environment. The experiments were conducted utilizing the potentiostatic method in potentiodynamic mode at a potential sweep rate of 2 mV/s. Results indicate that the introduction of lithium to the AlTi0.1 alloy leads to a shift in the potentials of free corrosion, pitting, and repassivation towards positive values. Additionally, the corrosion rate decreases by 10–20 % with the incorporation of 0.01–0.50 wt.% Li. Moreover, varying concentrations of chloride ions in the NaCl electrolyte prompt fluctuations in the corrosion rate of the alloys and a shift in electrochemical potentials towards the negative range.

Cyanide-refractory ores constitute 30 % of the world’s gold mineral resource base. With the global decrease in the availability of high-grade and free-milling ores, low-quality ores, including those rich in sulfur and arsenic, are increasingly being processed. The authors have conducted an assessment of the primary factors complicating the leaching process of refractory gold. These factors include the influence of gold distribution within the ore, the presence of preg-robbing effects, and the impact of cyanicidal minerals, notably pyrrhotite, on the leaching process. Sulfide minerals significantly affect the kinetics of gold leaching and associated reagent costs. The behavior of Fe₅S₆ is elucidated through the concept of “chemical depression”. Under cyanide leaching conditions, pyrrhotite actively and directly reacts with NaCN/KCN, undergoing surface oxidation by dissolved oxygen in the pulp. This leads to the formation of ferrocyanide complexes and rhodanides, which are unable to leach gold. Presently, there are two approaches to enhance the process parameters of refractory ore processing technology. The first approach involves the inclusion of preparation operations for cyanidation, aimed at liberating gold from the sulfide matrix (including hydrometallurgical and pyrometallurgical oxidation technologies and mechanical activation). An alternative approach is to use alternative reagents as leaching agents (notably thiourea, sodium and ammonium thiosulfates, and halides). The article explores means of modifying the technological process for gold extraction when ores contain substantial amounts of pyrrhotite or concentrates.

Through the optimization of processing parameters, including pressure, temperature, and deformation degree, a high pressure torsion (HPT) regime was identified. This regime allows for the creation of a unique microstructure in the biodegradable Zn–1%Li–2%Mg alloy, which exhibits exceptional physical and mechanical properties. Following 10 revolutions of HPT treatment (resulting in an accumulated deformation degree, γ = 571) at the temperature of 150 °C and an applied pressure of 6 GPa, the Zn–1%Li–2%Mg alloy displayed notable mechanical characteristics, including a high yield strength (~385 MPa), ultimate tensile strength (~490 MPa), and ductility (44 %) during tensile tests. To elucidate the underlying reasons for these remarkable mechanical properties, an examination of the alloy’s microstructure was conducted employing electron microscopy and X-ray phase analysis (XPA). The study revealed the formation of a distinct microstructure characterized by alternating bands of the α-phase Zn, a mixture of Zn and ~LiZn₃ phases, as well as the α-phase Zn containing Mg₂Zn₁₁ particles, as a consequence of HPT treatment. Additionally, it was observed that HPT treatment induced a dynamic strain aging process, leading to the precipitation of Zn particles in the LiZn₃ phase and the precipitation of Mg₂Zn₁₁ and β-LiZn₄ particles in the Zn phase. These precipitated particles exhibited a nearly spherical shape. The application of the XPA method helped to confirm that the Zn phase becomes the predominant phase during HPT treatment, and microscopy data showed the formation of an ultra-fine grained (UFG) structure within this phase. A comprehensive analysis of the hardening mechanisms, based on the newly acquired microstructural insights, revealed that enhanced strength and ductility of the Zn–1%Li–2%Mg UFG alloy can be attributed primarily to the effects of dispersion, grain boundary, and heterodeformation-induced hardening, including dislocation strengthening.

This article presents the results of a study focused on the formation of structural characteristics and properties of welded joints in the EP718 alloy with a 13 mm thickness (accounting for a 3 mm technological substrate). The study explores variations in electron beam welding parameters, such as beam current and the speed of its movement across the specimen’s surface, to determine the optimal welding mode for this alloy. This alloy is crucial in the production of high-pressure stators for aircraft engines, as the component operates under low-cycle loads at high stress levels, making its performance critical. Specimens that were welded with a beam speed (ν) of 0.0042 m/s and a beam current (i) of 85 mA exhibited a minimum tensile strength of 1160 MPa. On the other hand, specimens welded with ν = 0.006 m/s and i = 65 mA demonstrated a maximum tensile strength of 1270 MPa. However, it’s noteworthy that specimens welded at 0.006 m/s with beam currents of 120 mA and 75 mA experienced fracture along the weld, while specimens welded at 0.006 m/s with a beam current of 65 mA and at 0.0042 m/s with a beam current of 85 mA exhibited fracture in the heat-affected zone at a distance of 0.5–3.0 mm from the weld. Examination of the structure of specimens welded at ν = 0.006 and 0.0042 m/s and i = 120 mA, 75 mA, and 85 mA revealed expanded grain boundaries in the heat-affected zone. Consequently, the optimal welding mode was identified as having a beam speed of 0.006 m/s and a beam current of 65 mA. In this mode, no thickened grain boundaries were detected, and a maximum tensile strength of 1270 MPa was achieved.

This paper investigates the influence of partial substitution of titanium by its hydride on the microstructure and mechanical properties of TNM-B1 alloy obtained by powder metallurgy technology. The impact of the Ti:TiH₂ ratio in the reaction mixture and heat treatment modes on the microstructure and mechanical properties of TNM-B1+1%Y₂O₃ alloy, obtained using high-energy ball milling (HEBM), selfpropagating high-temperature synthesis (SHS), and hot isostatic pressing (HIP) methods, has been examined. It was observed that a 10 % substitution of titanium with its hydride in the reaction mixtures reduces the oxygen content in SHS products from 1 % to 0.8 % due to the generation of a reducing atmosphere during the decomposition of TiH₂ in the combustion wave. When the Ti : TiH₂ ratio is 90 : 10, highest mechanical properties of TNM-B1+1%Y₂O₃ alloy were achieved: a compressive strength (σ_u) of 1200±15 MPa and a yield strength (YS) of 1030±25 MPa. An increase in the proportion of TiH₂ results in a higher content of oxygen impurity, leading to the formation of Al₂O₃, which reduces the strength and ductility of the material. With additional heat treatment of TNM-B1+1%Y₂O₃ alloy, the globular structure transforms into a partially lamellar one, leading to an increase in σ_u by 50–300 MPa, depending on the TiH₂ content. This attributed to a decrease in the average grain size and a reduction in dislocation mobility during deformation.

An innovative technology has been developed and implemented for the restoration and manufacturing of new mold copper plates for continuous casting machines (CCMs) using wear-resistant composite coatings. These copper plates significantly surpass the service life of imported copper plates featuring galvanic coatings, sometimes by up to 20 times. However, the pressing challenge of restoring the copper plates of molds once they have reached the minimum permissible thickness remains unresolved. This study aimed to explore the feasibility of restoring a plate composed of precipitation-hardening Cr–Zr bronze with the same material by employing friction stir lap welding (FSLW). The objectives were to examine the structure, quality, and hardness of the welded joint, alongside investigating the impact of heat treatment (quenching and aging). By utilizing multi-pass FSLW method with a rotating tool crafted from a heat-resistant alloy and overlapping (partially overlapping) successive passes, a welded joint with a thickness of ~5 mm was achieved, devoid of critical continuity flaws (cracks or voids). Within the bronze layer restored through FSW, a softening effect ranging from 85–105 HV1 was observed compared to the initial hardness of the bronze in its hardened and aged state while in service (116–126 HV1). This is attributed to recrystallization and overaging, specifically the coarsening of chromium particles within the Cr–Zr bronze due to the heating of the weld nugget (stir zone) to 600–700 °C. The observed softening effect during FSW can be effectively rectified through heat treatment involving dissolution of the hardening phases followed by aging, resulting in a hardness increase to approximately 120–150 HV1. The process of restoring copper plates to their original thickness via the progressive and environmentally friendly FSW method, followed be the subsequent application of wear-resistant composite coatings, presents the opportunity for an almost infinite operational cycle of molds. This advancement could potentially eradicate the necessity for Russia to rely on importing such molds copper plates.