Search Results (2,426)

This study investigates the effect of sinusoidal arc oscillation frequency on bead geometry accuracy in Cold Metal Transfer-based Wire Arc Additive Manufacturing (CMT-WAAM) of the Al-4043 alloy. Single-pass depositions were performed at frequencies of 0–4 Hz (1.0 mm amplitude) and 0–5 Hz (1.5 mm amplitude), followed by multi-pass, multi-layer builds using optimal parameters. Cross-sectional analysis revealed that a 3–4 Hz frequency window minimizes wetting angle asymmetry and maximizes bead width-to-height ratio. At 4 Hz with 1.5 mm amplitude, the arc oscillation yielded a symmetric wetting angle deviation of only 1.22°. Multi-layer builds indicated that oscillation improved the effective cross-sectional area ratio from 75% (non-oscillating) to 82%, suggesting superior geometric efficiency and reduced material waste in post-machining. Full article

The increasing use of electric vehicles has led to a growing demand for rare-earth elements, particularly neodymium (Nd), which is a critical component of Nd–Fe–B permanent magnets used in traction motors. End-of-life electric vehicle motors are therefore considered promising secondary resources for Nd recovery. In this study, a pyrometallurgical process using non-ferrous smelting slag as a flux was proposed for recovering Nd from Nd–Fe–B magnets contained in waste electric vehicle motors. Steel and magnet fractions obtained from a dismantled motor were melted at approximately 1600 °C under an air atmosphere, and Fe₂O₃ was added as an oxidizing agent to promote the selective oxidation of Nd. The oxidized Nd was subsequently partitioned into the slag phase as Nd₂O₃ through metal–slag separation. The effects of the slag flux addition ratio, Fe₂O₃ content, slag flux type, and crucible material on Nd recovery behavior were systematically investigated. Increasing the fayalite-based slag flux addition enhanced Nd transfer into the slag phase, and the highest Nd recovery of approximately 80% was obtained at a slag flux addition ratio of 30 wt%. The addition of 2 wt% Fe₂O₃ was found to be suitable for promoting stable Nd oxidation and efficient slag–metal separation. The non-ferrous smelting slag exhibited chemical and phase characteristics comparable to those of synthetic fayalite slag flux, resulting in similar Nd recovery performance. In addition, the crucible material significantly affected the process stability and Nd recovery behavior. Although a carbon crucible showed relatively high Nd recovery, severe slag foaming and crucible erosion occurred during melting. In contrast, alumina and MgO crucibles provided stable process conditions with comparable Nd recovery behavior, whereas zirconia crucibles caused relatively higher Nd loss. These results demonstrate that non-ferrous smelting slag can be effectively used as a flux for the pyrometallurgical recovery of Nd from end-of-life electric vehicle motors, offering a potential route for sustainable rare-earth recycling. Full article

To reveal the effect of vanadium content on the viscous flow behavior of vanadium-containing hot metal, viscosity measurements and molecular dynamics simulations were conducted. The viscosity and melting characteristic temperature were measured. The local structures of Fe, V, and C atoms were analyzed using radial distribution functions, average coordination numbers, mean square displacements, and cluster evolution. Both viscosity and melting characteristic temperature increased with vanadium content. At 1300 °C, the viscosity increased from 11.8 to 19.9 mPa·s as the vanadium content increased from 0.20 to 0.30 wt%. The melting characteristic temperature increased from 1242 to 1323 °C. Structural analysis showed that increasing vanadium content promoted the redistribution of C atoms. The average coordination number of V–C increased from 7.780 to 8.218. In contrast, the coordination numbers of C–Fe and Fe–C decreased. The mean square displacements of Fe and C atoms also decreased, indicating that atomic diffusion was suppressed. Cluster evolution further showed that V–C structures could dissociate and recombine with Fe–C and Fe–V units. Therefore, increasing vanadium content reduced the fluidity of hot metal by increasing the melting characteristic temperature, strengthening V–C local coordination, and promoting complex cluster formation. Full article

Selective laser melting (SLM) and electron beam melting (EBM) enable the fabrication of commercially pure titanium, but the effects of the fabrication method and build orientation on surface characteristics and bonding remain unclear. This study evaluated the surface roughness, wettability, and shear bond strength of titanium fabricated by SLM and EBM at build orientations of 0°, 45°, and 90°, with titanium ingots intended for dental casting serving as reference specimens. The surfaces were wet-ground, air-abraded with 50 µm alumina particles, and treated with a 10-methacryloyloxydecyl dihydrogen phosphate-containing metal primer. Surface roughness (Sa), static water contact angles before and after primer application, and shear bond strength to a resin luting agent after 24 h of water storage were evaluated (n = 15/group). The EBM specimens fabricated at 90° exhibited significantly greater Sa values than the other groups (p < 0.05). Primer application significantly increased the water contact angle in all groups (p < 0.05), although group-dependent differences were observed. No significant differences in shear bond strength were detected among the fabrication conditions (p > 0.05). Thus, under the tested surface treatment conditions, differences in surface roughness and wettability were not accompanied by corresponding differences in the initial bond strength of commercially pure titanium. Full article

Energy-intensive foundries require methods to explore trade-offs among delivery performance, production horizon, electricity use, and cost when industrial data are incomplete. This paper presents an offline, process-level digital twin case study for the melting and casting area of a Danish cast-iron foundry. A multi-agent simulation represents production orders, enterprise resource planning and manufacturing execution system functions, induction furnaces, holding furnaces, crane-based transfer of molten metal, vertical moulding lines, the operating calendar, and electricity cost accounting for the induction furnaces. The model is assessed through boundary definition, assumption registration, implementation checks, material flow plausibility, a diagnostic comparison of furnace temperature, controlled scenario experiments, and local sensitivity analysis. These activities support internal consistency and bounded interpretation but do not constitute independent operational validation of the full production system. In the simulated 200-order monthly case, First-Come-First-Served and Earliest Deadline First complete the same 288,620 pieces and 5482.00 t. Earliest Deadline First increases the simulated on-time completion rate from 87.5% to 100%, while makespan, model-estimated electricity use by induction furnaces, and model-estimated electricity cost increase by 7.52%, 0.58%, and 3.42%, respectively. The case indicates that deadline-oriented sequencing may improve delivery performance but lead to a longer production horizon and higher energy use and cost within the defined model boundary. The contribution is an auditable foundry-specific modelling workflow that links heterogeneous data conditions to modelling choices, supporting evidence, and interpretation limits. The model is therefore intended for preliminary offline scenario exploration rather than validated operational decision support. Full article

Effects of varying lanthanum (La) content on the melting characteristics, spreadability, mechanical properties of brazed joints, and microstructure of low-silver BAg5CuZn brazing filler metal were investigated. The results indicate that the addition of La has little effect on the solidus and liquidus temperatures of the filler metal, while an excessive amount of La slightly raises its liquidus temperature. An appropriate amount of La enhances the spreadability of the filler metal on both copper and stainless steel plates and simultaneously inhibits grain growth, refining the microstructure of the BAg5CuZn-xLa filler metal. When the La content in the filler metal reaches 0.3%, the shear strength of the 304 stainless steel/304 stainless steel joint brazed with BAg5CuZn-xLa filler metal reaches 492 MPa, which is 17.7% higher than that of the brazed joint without the La addition. Full article

CO₂ methanation is a promising power-to-gas technology that enables the conversion of carbon dioxide into methane. However, the development of efficient catalysts based on naturally abundant and inexpensive support remains an important challenge. In this work, metakaolin from natural kaolin was investigated as a novel support for high-loading (30 wt.%) Ni catalysts prepared using a melt infiltration method. The influence of CeO₂ and alkaline earth metal oxides (MgO, CaO) on the physicochemical properties and catalytic performance was systematically evaluated. It was evidenced that CeO₂ improved NiO reducibility, whereas MgO and CaO promoted Ni⁰ dispersion and modified textural and surface properties. In particular, Mg addition increased the S_BET from 23 to 39 m²/g and the total pore volume from 0.06 to 0.17 cm³/g compared with the Ni-MK sample. The promoted catalysts exhibited enhanced low-temperature activity and reached approximately 80% CO₂ conversion at 400 °C, close to thermodynamic equilibrium, maintaining CH₄ selectivity above 97%. Stable catalytic performance was preserved during 24 h time-on-stream tests. The results demonstrate that metakaolin is a promising sustainable support for Ni CO₂ methanation catalysts and that melt infiltration provides a simple and effective preparation route for obtaining high nickel loading. Full article

In this work, first-principles calculations based on density functional theory were employed to investigate the structural, elastic, half-metallic, magnetic, and thermal properties of two novel quaternary Heusler alloys, FeMnLiSi and FeMnLiGe. The results revealed that ferrimagnetic FeMnLiSi and FeMnLiGe with type III structures were energetically the most stable, and possessed thermodynamic, dynamic, and mechanical stabilities. Their equilibrium lattice constants were 5.6104 Å and 5.7479 Å. At equilibrium, FeMnLiSi and FeMnLiGe exhibited brittleness, elastic anisotropy, and half-metallic ferrimagnetism, with half-metallic band gaps of 0.7935 eV and 1.0805 eV, respectively. The total magnetic moments per unit cell of FeMnLiSi and FeMnLiGe were both 2.0000 µB, which conforms to the Slater-Pauling rule. Their half-metallic ferrimagnetism remained robust over a broad range of uniform lattice strains. FeMnLiSi exhibited a higher stability, melting point, and Debye temperature, as well as a narrower half-metallic gap, than FeMnLiGe. This work systematically predicted the intrinsic structural, mechanical, magnetic, and thermal properties of FeMnLiSi and FeMnLiGe, and delivered theoretical insights for designing new Heusler-type half-metallic candidates. Full article

Glass additive manufacturing (AM) is a developing technology, particularly in comparison to metals and polymers, both of which have had their processes and applications extensively studied. Its potential lies in fabricating complex, even micrometric, geometries that are difficult or impossible to achieve via traditional molding, as well as in producing components with unique optical properties. The diversity of AM techniques, alongside the challenges associated with the high melting point, rheological control, and fragility of glass, necessitates a comprehensive analysis of current developments. Accordingly, this review presents a systematic review, conducted in accordance with the PRISMA protocol, of recent literature regarding AM technologies that fabricate glass via particle fusion to form solid components. This review explicitly excludes techniques utilizing glass fibers as reinforcement, as that constitutes a separate field of inquiry. The results demonstrate sustained growth within the field, with a predominance of technologies based on photopolymerization and ink extrusion, both of which offer high resolution and microstructural control. Ultimately, this review establishes the current state of the art, identifying critical challenges and emerging lines of research to guide future development. It is intended to serve as a foundational reference for researchers and professionals seeking to initiate or expand their work in glass AM. Full article

Rare-metal pegmatites of the Kalba–Narym belt (Eastern Kazakhstan) represent an important source of Li, Cs, Ta, Nb, Be, and associated critical metals. Despite extensive geological investigations, the relationships between granites, pegmatites, and late-stage alteration products within the Central Kalba ore district remain insufficiently constrained. This study integrates whole-rock geochemistry and muscovite trace-element data to evaluate regional fractionation trends and rare-metal enrichment within the granite–pegmatite system. The dataset comprises 29 whole-rock samples, including Phase I and Phase II granites, pegmatites, greisens, and hornfels, together with 11 muscovite separates from the Akhmetkino, Yubileynoye, Bakennoye, and Asubulak ore fields. Geochemical evolution was assessed using granite-normalized multi-element patterns and the Cs–Rb, K/Rb–Cs, Li–Rb, Li–Cs, Rb/Sr–Cs, and Ta–Cs relationships. Muscovite compositions were additionally compared with published datasets from the Totoral (Argentina) and Gatumba (Rwanda) pegmatite districts. The results reveal systematic enrichment in Li, Rb, Cs, Nb, and Ta accompanied by depletion in Sr and Ba from granites to the most evolved pegmatites. The strongest geochemical relationship is recorded by the Rb/Sr–Cs system (R² = 0.805), whereas Ta and Cs show only weak correlation (R² = 0.062). Muscovite compositions display decreasing K/Rb and K/Cs ratios and increasing Rb and Cs concentrations from Akhmetkino through Yubileynoye and Bakennoye to Asubulak, defining a regional fractionation sequence consistent with whole-rock geochemistry. The most evolved muscovites overlap compositional fields characteristic of highly fractionated LCT pegmatites. The geochemical patterns identified in both whole-rock and muscovite datasets indicate progressive melt evolution across the Central Kalba district. Late-stage alteration and volatile-rich mineral assemblages record additional fluid-related processes, although their quantitative contribution to rare-metal redistribution remains uncertain. The results identify Cs, Rb/Sr, K/Rb, and K/Cs as useful indicators of relative pegmatite evolution and provide new constraints on the development of rare-metal granite–pegmatite systems in Eastern Kazakhstan. Full article

Conventional soldered interconnects—necessarily requiring high-temperature processes to melt solder (tin)—are posing reliability challenges to crystalline silicon solar cell modules due to residual stress stemming from the mismatch of the coefficient of thermal expansion of the materials involved. On the other hand, electrically conductive adhesives (ECAs) have been shown to exhibit sufficiently promising improvements in mechanical and electrical properties to be used as silicon solar cell interconnects. However, the current ECA technology is dominated by ECAs with dispersed silver particles, which makes them costly and could cause embrittlement of the ECA at higher concentrations. This study investigates the potential application of a novel ECA, with composite metal particles, made of a nickel and Sn95Ag4Cu1 solder mixture and dispersed in a high-density polyethylene matrix for the solar cell interconnection. The test PV modules show comparable electrical and mechanical performance to that of soldered cell modules, despite the fact that the ECA application is still rather early in its learning curve. The present study suggests that the novel ECA could lead to a promising alternative to the conventional soldering process and the more costly silver-filled ECAs. Full article

The article presents the research findings on a collection of ceramic crucibles excavated at the Koksharovka-1 hillfort, known as one of the most significant archaeological sites of the Medieval epoch (7th–13th centuries) in the Russian Far East. This study represents an investigation of melting crucibles as a distinct category of metalworking ceramics discovered in the research area. The study is based on an integrated approach combining traditional archaeological analysis with physicochemical methods, including scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), X-ray fluorescence spectroscopy (XRF), Raman spectroscopy, electron probe microanalysis (EPMA), and computed microtomography (micro-CT). The research found that the morphological and technological properties of the crucibles were consistent with their function as containers for metal heat treatment. Traces of copper-based alloys as well as gold and silver processing were detected as a result of the crucible examination. For the first time, archaeological evidence of silver and gold metalworking in the Russian Far East during the Medieval epoch has been obtained. Full article

In this study, amorphous Cu₈₆P_7.5Sn_4.5Ni₂(wt.%) fillers were prepared using the melt spinning method with different rolling speeds. The wetting performance of these fillers on copper was assessed under different temperatures and holding times. The results indicated that the fillers obtained through the melt spinning technique exhibited lower melting temperatures than the as-cast filler. When processed at a rolling speed of 20 m/s, the amorphization of the filler was not sufficient. The higher rolling speed promoted the formation of the amorphous structure. The amorphous filler produced at 30 m/s exhibited the narrowest melting range and the lowest liquidus temperature (622 °C), which is approximately 100 °C lower than that of the as-cast filler (725 °C). Furthermore, the amorphous fillers also exhibited better wettability toward copper under the same conditions. Notably, the amorphous filler fabricated at 30 m/s demonstrated superior wettability at 750 °C for 90 s. Owing to the optimal wettability of the amorphized filler toward copper and the lower liquid temperature, the brazed copper joint achieved a shear strength of 223.2 MPa. The fracture of the four joints occurred in the base metal. In this study, we explored the brazing performance of amorphized Cu-based fillers, facilitating the solid bonding of copper at lower brazing temperatures. Full article

This review presents a current understanding of the relationship between the structure of multicomponent metallic melts and the processes of amorphization and nanocrystallization. Particular attention is paid to the thermal-temporal treatment (TTT) of melts as a precision method for monitoring the nonequilibrium state of the liquid phase, the relaxation kinetics of cluster associations, and liquid–liquid transitions (LLT). The mechanisms by which precrystallization melt treatment affects the homogeneity of the amorphous precursor, the size of nanograins (7–15 nm), the phase composition (Fe₃Si, Fe₂B), and the resulting magnetic characteristics of toroidal cores (μ_max > 600,000, H_c < 0.5 A/m) are investigated. Based on an analysis of structural models of metallic melts (cybotactic, quasicrystalline, and quasichemical), it is shown that critical temperatures, viscosity hysteresis, and oscillatory relaxation serve as indicators of melt equilibrium. It is noted that the optimized TTT protocols combined with controlled annealing at 542–572 °C enable the formation of Fe₃Si nanograins with exceptional magnetic softness. The results open the possibility of discussing the prospects for integrating TTT with in situ diagnostics, CALPHAD modeling, and the potential of machine learning for the design of next-generation soft magnetic nanomaterials with tailored frequency characteristics for high-frequency power electronics and their use in electromagnetic shielding. Full article

Metal/graphene composites with a metal matrix and graphene reinforcement are very promising innovative materials due to their improved mechanical and physical properties. In this paper, the possibility of fabricating a composite from a graphene network filled with nickel (Ni), copper (Cu) and aluminum (Al) nanoparticles is shown by molecular dynamics simulation. Composites are obtained by hydrostatic compression at 0.7 of the melting temperature of the metal nanoparticles. It is found that the Ni/graphene composite exhibits the highest ultimate tensile strength (89.5 GPa) and Young’s modulus (296.9 GPa) compared to 35.1 and 65.9 GPa for Cu/graphene and 36.8 and 109.1 GPa for Al/graphene, respectively. The Ni nanoparticles were uniformly distributed throughout the graphene network, providing high strength. Indentation simulations confirm this trend: the Ni/graphene composite exhibits a hardness 1.7 times higher than that of pure crumpled graphene, while Al/graphene shows a value 2.2 times lower, which directly correlates with the tensile strength. The Cu/graphene composite has the best ductility (fracture strain of 0.75 versus 0.45 for Ni/graphene and 0.47 for Al/graphene) due to the easier sliding between the Cu nanoparticles and the graphene during tensile loading. The Al/graphene composite has low strength and ductility because the Al nanoparticles tend to coagulate inside the graphene network and hardly interact with the graphene. For Cu/graphene and Al/graphene composites, fracture occurs at the metal/graphene interface. The results show that it is possible to fabricate metal/graphene composites that are much stronger than pure metal by deformation-temperature treatment. In addition, the mechanical properties can be modified by varying the type of metal. Full article