The Archives of Metallurgy and Materials is a quarterly journal of the Polish Academy of Sciences and the Institute of Metallurgy and Materials Science of the Polish Academy of Sciences, which has been publishing original scientific and review papers in the field of metallurgy and materials science since 1954. The journal website is being gradually updated as part of the migration from journals.pan.pl. The information on this page is current.
Institute of Metallurgy and Materials Science of Polish Academy of Sciences, Committee of Materials Engineering and Metallurgy of Polish Academy of Sciences
Mechanical and Conductive Properties of Silicone Filled Graphene Electrically Conductive Adhesive (ECA)
Electrically conductive adhesives (ECAs) are promising alternatives to traditional solders for flexible and lightweight electronic packaging. However, achieving high conductivity while maintaining good mechanical flexibility remains challenging. This study aims to develop a silicone-based graphene ECA modified with polyethylene glycol (PEG-600) to improve electrical and mechanical performance. Silicone/graphene ECAs were fabricated with varying graphene contents (0–9 wt.%) through controlled sonication and curing. The samples were characterized using tensile testing, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Electrochemical Impedance Spectroscopy (EIS). FTIR spectra confirmed successful graphene incorporation through the presence of –OH, CH, C=C, and C=O functional groups, with the –OH peak shifting to higher intensity at 7% loading. Electrical conductivity reached an optimum of 4.87×10–6 S/cm at 9% graphene, attributed to the formation of continuous electron pathways within the polymer matrix. Mechanical tests revealed maximum tensile strength (0.305 MPa) and Young’s modulus (146.523 MPa) at 7% graphene before decreasing due to filler agglomeration. SEM analysis supported these findings with uniform filler dispersion at optimum loading. The synergistic addition of graphene and PEG-600 effectively enhanced conductivity and mechanical stiffness, demonstrating strong potential for flexible electronic applications.
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Eco-Dying on ZnO Nanoparticles using Tamarindus Indica L. Seed Coat Tannin
This study aims to explore the potential of Tamarindus indica L. seed coat tannin as a natural dye sensitiser for zinc oxide nanoparticles. The tannin extract was prepared by mixing ground seeds with de-ionised water and utilised as a natural dye to sensitise ZnO nanoparticles, enhancing their optical absorption properties in the visible region. ZnO nanoparticles were synthesised in the presence of varying concentrations of Tamarindus indica L. seed coat tannin to investigate its impact on their growth and optical behaviour. Results demonstrated that the Tamarindus indica L. seed coat extract contained abundant polyphenolic compounds with characteristic hydroxyl groups, confirming its suitability as a natural sensitiser, while Fourier-transform infrared spectroscopy indicated strong chemical interactions between tannin molecules and zinc oxide through Zn–O bonding. Ultraviolet-visible analysis revealed that tannin incorporation extended the optical absorption edge of zinc oxide nanoparticles from 400 to 800 nanometres, shifting it into the visible spectrum. X-ray diffraction confirmed a hexagonal wurtzite structure with an average crystallite size of approximately 17 nanometres, supported by transmission electron microscopy observations. These findings demonstrate that Tamarindus indica L. seed coat tannin effectively enhances the light-harvesting capability of zinc oxide nanoparticles, offering a sustainable, low-cost approach for improving the optical performance of zinc oxide-based materials in dye-sensitised solar cells and other optoelectronic applications.
Investigation of Rod Pump Wear During Changes in Load Dynamics and the Design Trajectory of the Rod
The article is the first to investigate the mechanism of wear of the oil production pump couplings as a result of a violation of the design trajectory of kinematic connections from a given axis of symmetry. The critical values of the acting moments and stresses in case of inefficient load redistribution across the cylinder at different positions of the worn plunger are substantiated and presented. Using the Cauchy parameter model, an indirect assessment of the effect of dynamic loads on the actual capacity of the pumping unit is given, taking into account the wear of kinematic connections. It was possible to improve the Lame equation by describing the law of reciprocating motion of a plunger with uneven wear, as the equation of longitudinal elastic vibrations of the rod, taking into account the distributed specific external load acting on the rods, distorting the design trajectory of the kinematic pairs. The process of interaction of the elements of the rod-plunger-cylinder system of an oil production pump with uneven axial moments is investigated. The authors proposed a new term for the deviation of the design trajectory (Δλ) of the rod and plunger relative to the axis of symmetry of the cylinder. The mathematical model of pump capacity (Qa) and its resource life has been improved when changing the maximum allowable gap δt = f(i) in the plunger-cylinder system of a rod pump and leaks (qt) due to violations of the design trajectory (ΔλΣ) of kinematic pairs due to uneven distribution of dynamic loads. A dynamogram has been developed to determine the dependence of the load distribution on the movement of a worn plunger during basic contact stress cycles.
Impact on Low Concentration of f-MWCNTs/Fe3O4 Hybrid Filler on Electromagnetic Interference (EMI) Shielding Polymer at X-band
Preventing electromagnetic interference (EMI) signals from interfering with sensitive electronic devices can help protect it from damage. A lightweight, flexible, and thin EMI shielding polymer provides an alternative to the conventional rigid and heavy metal gasket. In this work, the f-MWCNTs/Fe3O4 hybrid filler was synthesised using the co-precipitation method and used as filler for the EMI shielding polymer. Low-concentration filler of less than 1% was seen as the solution to reduce production costs. Thus, this work used only 0.1 w/v% and 0.5 w/v% of filler concentration of the f-MWCNTs/Fe3O4 hybrid filler. Raman’s spectroscopy study confirmed the presence of carbon and Fe3O4 at 1200 to 1600 cm–1 and 686 cm–1 in the fillers, respectively. Examining the sample’s morphology indicates the filler’s length, diameter, and dispersion throughout the polymer. Electrical properties were studied using impedance spectroscopy, and EMI shielding effectiveness was measured using two-port methods. Results show that shielding polymer with 0.5 w/v% of f-MWCNTs/Fe3O4 hybrid filler results in 3.81×10–5 Scm–1 of electrical conductivity and 5.02 dB total shielding efficiency equivalent to 68.5% EM energy reduction. The total shielding efficiency increased to 8.32 dB (85.34% EM power shield) when the polymer thickness increased to 0.442 mm.
SEM and EDX Study of Zinc-Magnesium Phosphate Coatings on Mild Steel Surfaces
The work presents results of the formation, composition, structure and corrosion resistance of phosphate coatings on mild steel surfaces, obtained in zinc-magnesium phosphating solutions. The mass/thickness of the coating has been measured by means of gravimetric technique under the following conditions: concentration of the working solutions 5, 10, 15 and 20 vol.%; duration of the process 5, 10, 15 and 20 min; temperature 20, 40, 60 and 80°C. The elements that make up the coatings are determined by EDX analysis. The morphology and topography of the coatings are investigated by scanning electron microscopy (SEM). Potentiodynamic polarization measurement was used to determine the corrosion resistance and protective ability of the coatings.
Thermal Resilience of Eco-Binary Mortar: an Experimental Study of High-Temperature Exposure
Mortar exposed to high temperatures can experience significant degradation in strength and durability. One potential solution is replacing cement with alternative pozzolanic materials, such as Rice Husk Ash (RHA), which has a high silica content when processed under controlled burning conditions. This study investigates the use of RHA as a partial replacement in mortar, with additions ranging from 5 to 20 wt.%. As the amount of RHA increased, the mortar color darkened to a grayish shade. Surprisingly, the inclusion of 5 wt.% RHA resulted in almost double the compressive strength compared to conventional mortar, while 10 and 15 wt.% additions also showed improved performance. However, the addition of 20 wt.% RHA led to a decrease in compressive strength to 12.49 MPa, below that of standard mortar. High-temperature exposure (up to 1,093°C) affected the moisture content of the cement paste, changing its appearance to a whitish-gray color and impacting its mechanical properties. The relative strength values for all samples ranged between 0.35 and 0.16. Thermal analysis showed that free water evaporated between 82 to 140°C, followed by the decomposition of Ca(OH)2 at 445 to 454°C. The results suggest that 5 wt.% RHA provides optimal properties compared to other mixtures. This study highlights that RHA, as a low-cost agricultural waste, can be effectively utilized in the mortar industry, offering an environmentally friendly solution to both waste disposal and sustainability issues.
Corrosion Behavior of Mild Steel in Aqueous Solutions of Ammonium Nitrate
The aqueous ammonium nitrate solutions exhibiting a strong general or local corrosion attack to mild and low alloy steels. The corrosion aggressiveness is higher than nitrate solutions of alkali and alkaline earth metals to the same steels, mainly due to lower pH and complexing properties of NH4+-ions, which facilitates the passage of Fe2+-ions in the medium. Corrosion of iron and mild steel in NH4NO3 solutions have been studied by conventional methods and without providing information about the corrosion products and the probable reactions which control the corrosion processes. In the presented work, using electrochemical, physical, analytical and metallographic methods has been investigated the corrosion-electrochemical behavior of low-carbon mild steel (0.17% С) in aqueous solutions of ammonium nitrate. The corrosion-electrochemical parameters of the steel have been determined depending on the concentration, temperature and pH of the medium, as well the effects of thermal treatments – quenching and tempering at temperatures in the range of 200÷600°С. Under these conditions, the steel shows susceptibility or resistance to stress corrosion cracking (SCC). The corrosion products were determined by a Mössbauer analysis to correlate them with the corrosion behaviors of tested steels.
Substrate Patterning Effect on the Wetting Behaviour and Intermetallic Formation of SnCu Alloy
This paper explains the effect of a micro-patterned substrate fabricated via photolithography on soldering applications. The dimple micro-pattern was fabricated on the copper substrate with a 100–500 μm diameter with a fixed depth of 25±2 μm. The dimple micro-pattern substrate was metallurgically joined with Sn-0.7Cu lead-free solder in the reflow process. The dimple micro-pattern was examined using an optical microscope (OM) to observe all the critical parameters of the photolithography. The depth of the dimple(s) was observed and measured using a 3D surface profiler. The solder joints of the dimple micro-patterned substrate and the Sn-0.7Cu solder alloy were analysed in terms of their solderability, wettability, formation of intermetallic compounds (IMCs), and microstructures to determine the influence of dimple micro-patterning on the performance of the Sn-0.7Cu solder alloy. It was observed that a fixed depth of 25±2 μm was achieved for all dimple diameters at an etching time of 45 minutes. In terms of the performance of Sn-0.7Cu solder alloy on a micro-patterned substrate, it can be seen that as the diameter of the dimples increases, the flow rate and spreading area increase. At the same time, the IMC thickness decreased as the dimple’s diameter increased. The dimple micro-pattern substrate enhances copper diffusion, which reduces the β-Sn area and promotes Cu-Sn intermetallic formation, resulting in a rich, fine eutectic area of solder compared to its non-patterned counterpart.
Synergistic Effects of Hybrid Montmorillonite and Graphene Nanoplatelets on the Mechanical, Thermal, and Structural Properties of Epoxidized Palm Oil/Epoxy Composites
Vegetable oils (VOs) are increasingly recognized as promising renewable alternatives to traditional epoxy resins. However, their relatively modest mechanical and thermal properties often hinder broader application. To overcome these limitations, this study focused on enhancing the performance of epoxy/epoxidized palm oil (EEPO) through a synergistic reinforcement strategy involving hybrid nanofillers. The hybrid filler systems were developed by combining a fixed amount of graphene nanoplatelets (GNP) at 0.5 phr with varying loadings of montmorillonite (MMT) at 1.0, 1.5, and 2.0 phr. The hybrid fillers were incorporated into the developed resin system to evaluate their synergistic effects on the overall performance of the composite. Comprehensive characterization, including X-ray diffraction (XRD), scanning electron microscopy (SEM), flexural testing, and thermal analyses such as differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), was conducted to examine the structural, mechanical, and thermal behavior of the resulting composites. The hybrid composite containing EEPO/GNP-MMT (0.5:1.0) achieved the highest performance, with a 37.7% increase in flexural strength (86.31 MPa), a 9.5% increase in flexural modulus (2.87 GPa), and a 20.6% increase in glass transition temperature (67.79°C). TGA results revealed improved thermal stability due to the enhanced barrier effects and the filler-matrix interfacial bonding. These results highlight the synergistic role of hybrid MMT and GNP fillers in producing sustainable, high-performance epoxy composites for structural applications, protective coatings, and bio-based panels.
Experimental Investigations on the Durability and Performance of Industrialized Products used in the Wood Industry
The woodworking industry uses a wide range of industrial items, which are subjected to severe mechanical and tribological stresses. This paper presents experimental research that examined the behavior of various essential industrial parts used in the woodworking industry, with a focus on durability, friction coefficient and wear. The performance characteristics of the materials used were determined by friction and abrasion tests, combined with microstructural analysis and mechanical measurements. The results are useful for optimizing materials and component design, which increases the efficiency and durability of industrial equipment in this field.
Microstructure and Mechanical Properties of AA6061 Layered Sheet Fabricated by Four-Layer Stack Cold Roll-Bonding
Four-layer stack cold roll-bonding (4L-CRB) process is applied to enhance the mechanical properties of AA6061 sheet. Commercial AA6061 sheets having thickness of 1 mm, width 0f 40 mm and length of 300 mm were stacked to four layers, and roll-bonded by two-pass cold rolling. The as roll-bonded Al sheet was then annealed for 1h at temperatures from 200 to 500℃. The conventional rolling (CR) was also proceeded at ambient temperature for AA6061 sheet for comparison. For both CR and 4L-CRB, the as roll-bonded Al sheets showed a typical deformation structure, where the grains are elongated in the rolling direction. However, they exhibited different recrystallization behaviors between the CR and the 4L-CRB. The grain diameter of the specimens annealed at higher temperatures than 350℃ was smaller and more homogeneous in 4L-CRB than in CR. In addition, the mechanical properties of the specimens processed by 4L-CRB were more superior, comparing with those of the CR. The microstructures and mechanical properties of the specimens by 4L-CRB are compared with those by the CR in detail.
Properties of Cement-Solidified Soils for the Process Control Program
The performance of cement-solidified soil waste was evaluated following Process Control Program (PCP) guidelines. Illite-based soils were used as surrogate for radioactive soil waste. The optimal mixing ratio of water, cement, and waste was determined from compression strength and workability; the solidified block at a mixing ratio of 25 wt.% water, 50 wt.% soil, and 25 wt.% cement exhibited 12.7 MPa of compression strength with good workability. Cement-solidified soil blocks in PCP size (diameter: 100 mm; height: 200 mm) were fabricated at the determined mixing ratio. Compression, immersion, thermal cycling, and irradiation tests were performed on the solidified blocks. The cement-solidified blocks passed the acceptance KORAD criteria for disposal, satisfying a compression strength above 3.44 MPa after all tests. Leaching tests were performed by piking radioactive natural soils (39.36 Bq/g), showing no radioactivity. These results suggest that radioactive soil waste can be solidified with cement by following PCP guidelines.
UV Pulse Sequence-Dependent Properties of Al2O3 Films Via UV-Assisted Atomic Layer Deposition
Uniform thin-film deposition on temperature-sensitive or particulate substrates remains challenging at low temperatures. Energy-enhanced atomic layer deposition offers an effective approach to activate surface reactions by supplying external energy such as plasma, mechanical input, or photon irradiation. In this work, Al2O3 thin films were deposited at a low temperature of 85°C by UV-assisted atomic layer deposition, and the effects of UV irradiation conditions on film properties were investigated. Under UV irradiation, the growth rate increased, while surface roughness and residual carbon content decreased, accompanied by an increase in the Al–O bonding fraction. These results demonstrate that UV-assisted atomic layer deposition enables high-quality Al2O3 coatings even under low-temperature conditions and suggest its potential applicability to powder surface modification processes.
Effect of Washing Process on the Magnetic Property of Sm2Fe17 Nanopowder Prepared by Modified Reduction-Diffusion Process
This study investigates the influence of an improved washing process on the magnetic properties of Sm2Fe17 nanopowders synthesized via modified reduction-diffusion (MRD) process. In particular, hydrazine (N2H4) was used to reduce dissolved oxygen in deionized (DI) water, aiming to minimize oxidation during the removal of byproduct CaO. Compared to conventional DI water washing, the N2H4-treated process significantly reduced the oxygen content in the nanopowder from 2.53 wt.% to 0.85 wt.%, while also lowering residual Ca from 0.56 wt.% to 0.32 wt.%. As a result, the saturation magnetization (Mₛ) increased significantly from 73.9 emu/g to 127 emu/g, and coercivity (Hc) remained stable around 1150 Oe. These results highlight the critical role of wash water chemistry in preserving the intrinsic magnetic performance of Sm2Fe17 nanopowders and optimizing their suitability for permanent magnet applications.
Evaluation of Valuable Metal Recycling Behavior using Nickel Sulfate Waste Solution and Pre-Treatment by-Products Recovered from Waste Lithium-Ion Batteries
In this study, high-crystallinity nickel metal powder was synthesized from a nickel sulfate solution recovered from Lithium-Ion Batteries (LIBs) waste via a continuous precipitation-liquid phase reduction process. The effects of hydroxide precipitation conditions and reducing agent concentration on phase formation, crystallinity, and particle morphology were systematically investigated. Nickel hydroxide was first prepared as an intermediate product by controlling the [OH]/[Ni] molar ratio using sodium hydroxide as a precipitant, followed by liquid-phase reduction with hydrazine to produce metallic nickel powder. Single-phase nickel metal powder was obtained under [OH]/[Ni] = 7–14 conditions, with average particles sizes ranging from 4.05 to 4.35 μm.
Thermochemical Decontamination of Paper Wiper Wastes through Combined Carbonization and Chlorination
Chlorination has been used for the thermochemical decontamination of radioactive waste to address the significant amount of waste in nuclear facilities. Control of chlorination conditions is essential to optimize decontamination efficiency, as these conditions significantly influence chemical and physical evolution of target waste. In this study, the feasibility of thermochemical decontamination for reducing the radioactivity of paper wiper waste was investigated. A two-step thermochemical process, comprising low-temperature carbonization and high-temperature chlorination, was suggested to improve the decontamination efficiency. Simulated paper wiper waste contaminated with Cs and Co was treated in a closed system filled with air at 250°C for carbonization as a pretreatment. Subsequently, the partial carbonization product was chlorinated at 700–900°C to remove Cs and Co. Decontamination efficiencies of more than 99% were obtained after the two-step thermochemical process.
Microstructure Evolution of Nickel Strike Plating Layer by Electrochemical Deposition and Heat Treatment
Nickel strike layers were electrodeposited on stainless steel from a NiCl2-HCl bath, and the effects of applied potential, deposition time, and post-plating heat treatment were investigated. Chronoamperometry showed that cathodic current density increased and current fluctuations became more pronounced at more negative potentials, indicating intensified hydrogen evolution. Surface images revealed needle-like morphology at less negative potentials, whereas non-uniform deposition with incomplete coating regions appeared at –1.8 V due to competition from hydrogen evolution. Heat treatment transformed the surface into polygonal grains and promoted grain coarsening. Texture analyses indicated increased average grain size and decreased local misorientation, suggesting microstructural recovery and relaxation of residual/internal stress.
Performance Enhancement of LCM-Based Additively Manufactured Magnetic Composites via Spark Plasma Sintering
This study explores spark plasma sintering (SPS) to improve the microstructural integrity and magnetic performance of NdFeB composite parts produced by lithography-based composites manufacturing (LCM). The composites, containing 84 wt.% NdFeB in a photosensitive polymer matrix, were magnetically aligned during printing using an in-situ field. SPS, applying pulsed current and uniaxial pressure under vacuum, was used to achieve densification while limiting grain growth. Samples were sintered at various temperatures with or without a magnetic field. Microstructure was examined via electron backscatter diffraction (EBSD) and X-ray diffraction (XRD), and magnetic properties were measured by Vibrating Sample Magnetometer (VSM). Optimized moderate-temperature, field-assisted sintering enhanced densification and magnetic anisotropy, whereas excessive sintering caused degradation. The combined use of in-situ magnetic alignment and SPS enables dense, anisotropic additively manufactured NdFeB composites with improved performance.
Non-Isothermal Reduction Behavior and Microstructural Characteristics of MoO3 Powder in Pure Hydrogen Atmosphere
The reduction behavior and microstructure of both raw and ball-milled MoO3 powders have been investigated. The raw powder consisted of coarse plate-shaped particles, whereas the powder ball-milled for 5 h showed agglomerates composed of fine equiaxed particles. XRD analysis of the hydrogen-reduced powders indicated that only the diffraction lines for Mo are observed. In contrast, the milled powder exhibited the main peak of Mo and carbides peak as minor phases. The reduction kinetics of MoO3 powders were evaluated by analyzing the extent of peak shift at various heating rates using thermogravimetric analysis. The activation energies for the raw powder were determined to range from 97.5 to 104.4 kJ/mol, which are approximately consistent with the values reported for the isothermal reduction of MoO3 in a hydrogen atmosphere. For the ball-milled powders, the activation energy was measured to be 148.8–167.1 kJ/mol, which was interpreted to be related to the carbides formed by the reaction of Fe and C impurities with Mo.
Effect of Pb Addition on the Solidification Microstructure and Precipitation Behavior of Al–10Si–0.4Mg–0.4Cu Alloy Fa bricated by High-Pressure Die Casting
We studied the effect of Pb addition on the solidification microstructure and precipitation behavior of an Al–10Si–0.4Mg–0.4Cu alloy fabricated by high-pressure die casting (HPDC) using thermodynamic calculations and scanning and transmission electron microscopy analyses. Pb addition induced the formation of Pb phase along the grain boundaries of Al and Al/Si eutectic during solidification. Aging at 160°C induced the formation of spherical or needle-like Si nanoprecipitates and embedded β'' nanoprecipitates in both Pb-free and Pb-added alloys. Strong Pb segregation was observed at the interface of Si nanoprecipitates, which inhibits precipitate growth during aging. Si refinement due to Pb segregation and newly formed Pb nanoprecipitates slightly enhanced the age hardening reaction after T5 heat treatment. This study can provide insights into the strategies to control the microstructure of recycled HPDC Al alloys containing Pb.
Microstructure and Mechanical Properties of P-Modified Al–25Mg2Si–6Mg–11Cu–11Zn Alloy
We study the microstructure and precipitation behavior of P-modified Al–25Mg2Si alloy with excess Mg, Cu, and Zn. The addition of P significantly refines the primary Mg2Si phase from 165 to 43 μm due to enhanced heterogeneous nucleation at the Mg3P2 phase. This refinement leads to improvements in compressive strength from 440 to 585 MPa and fracture strain from 3.0 to 3.6%. The solution-treated alloy containing partially spheroidized and smoothed secondary phases exhibits significant age hardening at both 25°C and 120°C. Transmission electron microscopy (TEM) and small-angle neutron scattering (SANS) analyses confirm the formation of Guinier-Preston (GP) zones, η', and η nanoprecipitates during aging at 120°C. Solution and subsequent peak-aging enhance the compressive strength from 585 to 722 MPa and fracture strain from 3.6 to 4.0% of the alloy.
Effect of Complexing Agent in Nickel Displacement Deposition on the Exothermic Reactivity of Aluminum Powder
Aluminum powder is a representative energetic material with high heat release during oxidation. However, its performance is limited by its native oxide film. In this study, nickel displacement plating is applied to enhance the heat generation behavior of aluminum powder by utilizing the potential difference between aluminum and nickel. Citric acid, ammonium citrate, and malic acid were employed as complexing agents to control the plating behavior, and their effects on the nickel displacement plating morphology and exothermic characteristics were systematically compared. The enhanced heat generation is attributed to a self-propagating high-temperature synthesis reaction associated with the formation of Al-Ni intermetallic compounds. These results demonstrate that the choice of complexing agent is a critical factor in tailoring the reactivity of nickel-coated aluminum powder for energetic applications.
Effects of Dry and Wet Ball Milling on the Structural and Optical Properties of ZnO Powder
Zinc oxide is a promising material for optoelectronic and UV-protection applications due to its biocompatibility, wide bandgap, and excellent optical properties. Since these properties are highly dependent on the microstructure, precise process control is essential for optimization. However, research on the high-value-added applications for ZnO recovered from industrial byproducts remains limited. In this study, the particle size and morphology of ZnO powder synthesized from waste zinc dust were controlled via dry and wet ball milling processes. The correlation between microstructural changes driven by milling conditions such as rotational speed and process method, and the resulting optical properties, including UV transmittance and photoluminescence, was systematically investigated. The results showed that the microstructure and UV transmittance of the ZnO powders changed distinctly depending on the milling parameters. Notably, the wet ball milling condition at 600 rpm achieved a minimum transmittance of 10.0%, demonstrating superior UV-shielding performance. This study demonstrates that the structural and optical properties of waste-derived ZnO powder can be effectively tuned through ball milling, suggesting the potential for utilizing industrial byproducts as functional UV-shielding materials.
Microstructural Characterization of a Cr–Mo–W–Co Hot-Work Die Steel After Tempering
The microstructural characteristics of a Cr–Mo–W–Co hot-work die steel subjected to tempering were systematically investigated using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). All analyses were conducted under a unified tempering condition of 580°C for 6 h in order to establish a coherent interpretation of the stabilized microstructural state. SEM observations revealed the presence of micrometer-scale bright particles whose size and distribution remained unchanged after tempering, indicating that they are pre-existing carbides rather than tempering-induced precipitates. EBSD analysis showed a pronounced change in local crystallographic substructure after tempering, as evidenced by an increase in kernel average misorientation, suggesting sub-grain scale rearrangement within the matrix. TEM and selected area electron diffraction confirmed the formation of crystalline precipitates with well-defined interfaces, which could not be resolved by SEM. STEM-EDS analysis further demonstrated that these precipitates are Mo–W-rich complex alloy carbides incorporating multiple alloying elements.
Effect of Ceramic Crucible (Al2O3 or MgO) on Y Pre-Alloyed Ferritic Steel Fabricated by Vacuum Induction Melting
In this study, yttrium (Y) pre-alloyed ferritic steel was produced by vacuum induction melting casting. During casting, two types of ceramic crucible, Al2O3 and MgO, were used. The initial Y content was set to 1.2 wt.% in Fe-14.6Cr (in wt.%) ferritic steel. Inductively coupled plasma-atomic emission spectroscopy revealed that the remaining Y content was 0.04 wt.% in ferritic steel using an Al2O3 crucible, compared with 1.06 wt.% in steel using an MgO crucible. Energy dispersive X-ray spectroscopy analysis confirmed the formation of Y-Al-O oxides in ferritic steel (Al2O3), while X-ray diffraction detected the Fe5Y phase in ferritic steel (MgO). According to reported Y2O3-Al2O3 and Y2O3-MgO phase diagrams, Y2O3 is insoluble in Al2O3 but soluble in MgO. These results indicate that the MgO crucible is more suitable for preventing Y loss during vacuum induction melting.
Enhanced Plastic Deformation Behavior of Zr62Al8Ni13Cu17 Bulk Metallic Glass Matrix Composites Reinforced with SiC Particles
Zr62Al8Ni13Cu17 bulk metallic glass matrix composites reinforced with SiC particles were fabricated by spark plasma sintering using gas-atomized amorphous powders. The effects of SiC volume fraction on the microstructure and mechanical behavior were investigated. Dense microstructures with uniformly distributed SiC particles were obtained while preserving the amorphous matrix without crystallization. Compression tests demonstrated that the addition of SiC significantly enhanced both strength and plastic deformability. The composite containing 15 vol.% SiC exhibited a compressive strength of 1670 MPa and a total strain of 4.1%. The improved plasticity is attributed to the formation of multiple shear bands, suppression of shear band propagation, and enhanced interfacial stability associated with the viscous flow of the amorphous matrix.
Effect of Temperature on Microstructure and Texture Development in A7075 Aluminum Alloy Subjected to Biaxial Alternate Forging
In this study, the microstructural evolution of an A7075 aluminum alloy subjected to severe deformation by biaxial alternate forging (BAF) was investigated at room temperature (RT) and 300°C. SEM-BSE observations revealed no significant differences in the morphology or distribution of second-phase particles between the two conditions, indicating that deformation temperature did not markedly affect particle fragmentation at the applied strain level. However, SEM-EDS analysis of the matrix showed a noticeable reduction in Zn content after deformation at 300°C compared to RT, suggesting enhanced solute redistribution during high-temperature deformation. EBSD analyses demonstrated clear differences in deformation microstructures depending on both temperature and strain localization. At RT, the high-deformation region exhibited pronounced lattice distortion and heterogeneous orientation gradients, whereas deformation at 300°C resulted in more uniform IQ contrast and reduced intragranular misorientation, indicative of active recovery. Texture analysis based on ODF sections and pole figures showed moderate development of shear and rolling texture components, with more continuous and stabilized texture features at 300°C. These results indicate that elevated-temperature BAF promotes solute redistribution and recovery-assisted plastic flow without significant alteration of second-phase characteristics.
White-Light Emission from Single-Material ZnSe-Based Quantum Dots Synthesized under Aqueous Conditions
Quantum dots (QDs) are promising luminescent materials due to their tunable bandgaps and high color purity. White-light emission was achieved using ZnSe-based QDs synthesized under low-temperature aqueous conditions. ZnSe/ZnS, Cu-doped ZnSe/ZnS, and Mn-doped ZnSe/ZnS QDs prepared in deionized water at 90°C exhibited blue, green, and orange emissions, respectively. A ZnS shell enhanced optical stability, and white light was realized by physically mixing single-family QDs with different dopant centers. Optimized mixing of peaks at ~370, ~514, and ~578 nm produced a broad spectrum (~350–580 nm), and a 1:5:6 mixture yielded chromaticity coordinates near the CIE D65 white point. This study demonstrates a simple and effective approach for white-light generation using aqueous-synthesized ZnSe-based QDs.
Effect of Compositional Design in Ag-Cu-Based Brazing Alloys on Microstructure and Cu-STS Joining Characteristics
In this study, a copper-silver-phosphorus-tin brazing filler metal with reduced silver content was designed to facilitate oxide removal and enable fluxless brazing. Based on thermodynamic phase diagram analysis, the silver and tin contents were fixed, and the influence of phosphorus content on microstructure and joint strength was investigated. Increased phosphorus content resulted in a higher fraction of copper-phosphorus intermetallic phases. The filler metal containing 65 wt.% copper, 10 wt.% silver, 5 wt.% phosphorus, and 20 wt.% tin exhibited excellent wettability and a stable interfacial microstructure at 900°C. In addition, it achieved superior joint strength compared with a commercial copper-phosphorus filler metal and showed performance comparable to that of a conventional silver-based filler metal. These results demonstrate the potential of the developed filler metal as a cost-effective solution for copper-stainless steel cooling pipe applications.
Effect of Surface Roughness on the Sheet Resistance of CP Titanium Foils
In this study, we investigated the effect of physical surface roughness on the sheet resistance (Rs) of commercially pure titanium (CP-Ti, Grades 1, 2, and 4) foils with varying impurity compositions. Microstructural observations revealed that the grain sizes of Grades 1 and 2 were 24 and 20 μm, respectively, whereas Grade 4 exhibited a very fine microstructure with indistinct grain boundaries. The surface roughness of the as-received CP-Ti foils was approximately 0.05–0.06 μm, showing no significant difference among the grades. However, the sheet resistance was determined to be 4.05, 4.60, and 4.82 mΩ/□, respectively, indicating an increase with higher impurity content. In contrast, when the surface roughness was mechanically controlled, the sheet resistance of all specimens increased with increasing surface roughness for all grades, confirming a linear correlation between surface roughness and sheet resistance.
Enhancing Filtration Performance of Sintered Metal Filters Through Pore Structure Modification using Fine Flake-Shaped Particles
Sintered metal gas filters commonly suffer from a trade-off between filtration efficiency and gas permeability due to limited control over pore structure. In this study, fine flake-shaped stainless steel 316L powders were introduced into a sintered filter matrix to modify pore geometry without significantly reducing porosity. Microstructural and pore analyses showed that flake addition subdivided interparticle voids, leading to reduced pore size while maintaining high open porosity at low flake contents. Notably, the filter containing 1 wt.% flake-shaped powder exhibited a clear improvement in filtration efficiency without a pronounced increase in pressure drop. At higher flake contents, further gains in filtration efficiency were accompanied by a rapid increase in flow resistance. This work demonstrates that the controlled incorporation of fine flake-shaped powders provides a simple and scalable approach to pore-structure engineering for high-performance metal gas filters.
Magnetic Pulsed Compaction and Pressureless Sintering of Aluminum Matrix Composite Reinforced by TiC Particles
This study investigated the effects of magnetic pulsed compaction pressure and pressureless sintering conditions on the microstructure and mechanical properties of aluminum matrix composites. Al-10 vol.% TiC composites were fabricated using magnetic pulsed compaction under two different pressures (1.5 GPa and 3 GPa), followed by pressureless sintering under three conditions: 500°C for 2 h, 600°C for 1 h, and 600°C for 2 h. Phase analysis, density, microstructural characterization, and hardness measurements were conducted to evaluate and compare the properties of the fabricated specimens. The results showed that no new phases were formed during the sintering process in any of the specimens, and no significant differences in microstructure were observed. Specimens compacted at 3 GPa exhibited higher green density than those compacted at 1.5 GPa, and the relative density increased with higher sintering temperature and longer holding time. The hardness of the specimens showed a trend similar to that of density, with the specimen compacted at 3 GPa and sintered at 600°C for 2 h exhibiting the highest density and hardness.
Optimization of Cementitious Wasteform for Immobilizing C-14 in CaCO3 Radioactive Waste
This study examines the feasibility of immobilizing dispersive CaCO3 radioactive waste containing C-14 carbonate based on ordinary Portland cement (OPC) hydration. Cementitious wasteforms were fabricated by incorporating CaCO3 of waste loadings ranging from 20 to 60 wt.% by a conventional cement paste method. The performance of wasteform was evaluated in terms of mechanical and chemical durability specified in the waste acceptance criteria (WAC) for low- and intermediate-level radioactive waste disposal in the Republic of Korea. The compressive strength was evaluated under open and sealed curing conditions at curing periods of 7 and 28 days. As CaCO3 content increased, the compressive strength was generally reduced, however, maximum value was obtained under 30 wt.% CaCO3 with all curing conditions. Chemical durability was evaluated according to the ANSI/ANS-16.1 method. Linear cumulative leaching behavior of carbon was shown for all compositions. The leaching indices was derived with ranging of 12.0-12.7, corresponding to extremely low effective diffusion coefficients. Therefore, it was shown that OPC-based hydration provides an effective and acceptable immobilization strategy for dispersive CaCO3 radioactive waste.
Enhancement of Mechanical Properties, wear resistance and EDM performance of Biodegradable Magnesium alloy MMC
In this study the mechanical, wear, and electrical discharge machining (EDM) performance of biodegradable WE43 magnesium alloy was enhanced by adding ceramic reinforcement like silicon carbide, aluminium oxide, and boron carbide. Two hybrid composite specimens were fabricated in this investigation with WE43 MMC 1 is reinforced with 6 wt.% reinforcement (2% SiC, 2% Al2O3, and 2% B₄C) and WE43 MMC 2 with 10 wt.% reinforcement (3.5% SiC, 3.5% Al2O3, and 3% B4C). The weight % of ceramic reinforcement content is increased, the yield strength is enhanced from 158.69 MPa to 211.47 MPa, ultimate tensile strength is improved from 241.25 MPa to 285.36 MPa, and hardness from 65.8 to 89.4. However, there was a drop-in ductility, with elongation falling from 6.52% to 3.25%, showing that there is a trade-off between strength and plasticity. The hard-ceramic content made the material more resistant to wear and are expected to make EDM easier by reducing electrode wear and improving surface quality because they are more thermally stable. SEM and EDS analysis are carried out in this study to evaluate the microstructural and surface topography of WE43 MMC. The result of this study demonstrates that the WE43 MMC 2 are promising candidates for high-performance applications in biomedical and aerospace sectors requiring lightweight materials with superior mechanical and EDM-compatible properties.
Crystallization behaviour of Zr50Cu40Al10 metallic glass with different relaxed state
Zr50Cu40Al10 glass-forming alloy was synthesized at different cooling rates conditions, ranging from 101 to 107 K s–1, to investigate how structural relaxation affects crystallization behaviour and processing stability. XRD confirmed that rapid solidification suppresses crystallization, while DSC revealed supercooled liquid regions. Activation energies obtained by Kissinger and Ozawa analyses increased with cooling rate, reflecting the dominant role of structural disorder induced by high cooling rate delays nucleation via increasing atomic rearrangement cost. These findings clarify the kinetic-thermodynamic balance controlling crystallization and provide guidelines for tailoring Zr-based metallic glasses for thermoplastic forming and controlled nanocrystallization applications.
FE Analysis of Roll Wear during Railwa y Rail Rolling Process
The article presents the development of new roll pass designs for rolling of the MAV48, P50 and 50E2 railway rails under the production conditions of the D-815 rolling mill at ArcelorMittal Poland S.A. The aim of the study was to design, using computer simulations, a roll pass geometry ensuring the required dimensional accuracy of the final product while minimizing roll wear and ensuring stable rolling conditions. The roll pass design was developed using a CAD computer program, which enabled precise modeling of pass geometry and their arrangement in the rolling mill. The developed solutions were verified using numerical simulations, and then implemented in industrial conditions for production. The obtained results confirmed the correctness of the design assumptions and indicated the possibility of implementing the developed roll pass system in industrial practice.
Microstructural Analysis of Corrosion Mechanisms in Rotary Rings of Calcining Furnaces Used in Soda Ash Production
Severe surface corrosion of riding rings in rotary steam calcining furnaces commonly occurs during soda ash production, threatening operational stability and increasing maintenance costs. In this study, forged 35CrMo steel riding rings were investigated to clarify their corrosion behaviour and mechanisms. Environmental media analysis combined with hardness testing, metallographic observation, chemical composition analysis, and SEM-EDS characterisation was employed to examine microstructural evolution, corrosion morphology, and mechanical degradation. The results demonstrate that the corrosion is governed by the synergistic action of electrochemical corrosion in an alkaline dust environment, hydraulic shock caused by lubricant entrapment, and alternating compressive stresses during operation. Pronounced iron oxide formation, severe surface damage, and significant hardness reduction were observed in corroded regions. This study elucidates the coupled corrosion mechanisms of riding rings and provides guidance for lubrication optimisation and service life extension of critical components.
A Study of Al 7075 Alloy’s Strengthening and Wear Resistance with SiC and Graphite Hybrid Reinforcement
The hybrid reinforcement of SiC and graphite was used to study the mechanical and tribological properties of Al 7075 alloy. Five weight percent Gr and ten weight percent SiC were added to Al 7075, which has a very high strength-to-weight ratio. The testing included hardness, wear resistance, tensile strength, and coefficient of friction. The hybrid composite performed better than the unreinforced alloy in all respects. Hardness increased from 130–135 BHN to 170–180 BHN, and tensile strength increased from 510–540 MPa to 600–630 MPa. The wear rate decreased from 8.5 × 10⁻⁴ to 3.5 × 10⁻⁴ mm³/N·m, and coefficient of friction reduced to 0.30–0.32. SEM studies revealed good distribution of reinforcement with less porosity. The main advantage of this hybrid composite is SiC bearing the load, whereas graphite provides good lubrication.
Comparative Study on Welding Efficiency, Macrostructural/Microstructural Characteristics, and Mechanical Properties for Seven-wire Rotating Arc Electrogas Welding and Single-wire Electrogas Welding
The Use of Segmented Dies for Plastic Forming the Heads of Bolts on Forging Machines
Fasteners such as bolts constitute an important group of products in the metal industry. Owing to their wide industrial use, methods ensuring dimensional accuracy, process repeatability, and low manufacturing costs are crucial. Bolt heads are most commonly formed by cold forging. The aim of the article is to analyze the application of segmented dies for forming bolt heads with a concave–convex lateral surface in the cold forging process. The authors seek to demonstrate that the use of such tooling enables high dimensional accuracy to be achieved without the need for additional machining. The obtained results indicate that, the modular design of the dies makes it possible to obtain the required geometry within a five-operation process, which shortens the production cycle, reduces tool wear, and lowers manufacturing costs, while improving overall process efficiency. The shape of the head can be effectively controlled through strategic modifications of die geometry, careful sequencing of dies, and the implementation of supplementary radius smoothing during rolling. The presented approach constitutes a significant contribution to the development of cold forging technology, offering more economical and efficient methods for manufacturing fasteners with complex geometries.
Microwave static calcination for removal of high chlorine from hot-dip galvanizing ash for preparing ceramic glaze-grade zinc oxide
Microstructure, microhardness and wear behavior of TiN-based surface layers formed on commercially pure titanium Grades 2 and 4 by laser processing