Engineering

Abstract: The interfacial reaction and shear behavior of Sn-19Bi-19In (SBI) solder joints on an electroless nick-el/electroless palladium/immersion gold (ENEPIG) surface finish were investigated during isother-mal aging at 85 °C for durations of up to 500 h and compared with those of the SBI joints on elec-troless nickel/immersion gold (ENIG) reported previously. A thin densely packed needle-like in-termetallic compound (IMC) layer formed at the interface and grew with aging time. According to scanning electron microscopy (SEM) and electron probe microanalysis (EPMA), the IMC layer is suggested to be (Ni,Pd)(Sn,In)₂, and Pd was concentrated in the upper part of the IMC layer after aging. Since the composition of the IMC layer is similar to that of the loosely stacked cuboid Ni(In_0.3Sn_0.7)₂ IMC on ENIG, the difference in morphology is likely due to the participation of Pd in the formation of the (Ni,Pd)(Sn,In)2 IMC. Transmission electron microscopy (TEM) analysis of the interface at the initial stage of the reaction suggests that Au(In,Sn)₂ and (Pd,Ni)(Sn,In)₄ IMCs form prior to the (Ni,Pd)(Sn,In)₂ IMC. In ball shear tests, the SBI/ENEPIG joints showed a gradual duc-tile-to-brittle transition with aging time, and the crack path tended to shift from the solder bulk to-ward the IMC/Ni₃P interface. The maximum shear strength of the SBI/ENEPIG joints remained at 39.5–44.2 MPa on average, whereas that of the SBI/ENIG joints decreased with aging time. This difference in the maximum shear strength can be attributed to the difference in the IMC morphology between the two surface finishes.

Abstract: The Middle Group (MG) chromitites of the Bushveld Complex host a substantial, largely untapped platinum-group element (PGE) resource, yet remain far less studied than the dominant UG2 chromitite and Merensky Reef. This review synthesises the published literature on the MG1–MG4A seams, covering stratigraphic setting, silicate and sulphide gangue mineralogy, platinum-group mineral and base-metal-sulphide relationships, and the comminution, flotation and comparative-metallurgy factors distinguishing MG processing from UG2 and Merensky practice, including the mineralogical drivers of circuit configuration and methods used to diagnose PGE losses to tailings. Four persistent gaps are identified: (i) absence of a reef-resolved PGM inventory across MG1–MG4A; (ii) limited data linking comminution and mineralogy to flotation reagent selectivity; (iii) an almost complete absence of published ore-blending studies; and (iv) a fragmented evidence base for MG-specific tailings reprocessing. Two recent, reef-resolved experimental studies from this research group are presented as a first step toward closing gaps (i) and (ii), and a three-part research agenda is set out a factorial blend-design programme, a standardised automated-mineralogy protocol, and an integrated gravity–magnetic–flotation circuit for MG tailings aimed at closing the remaining gaps and advancing Middle Group ore toward the geometallurgical maturity already achieved for UG2 and Merensky ore.

Abstract: Pipeline transportation systems (PTS) are widely used maritime and land-based means of transport across several industries, including oil and gas, valued for being reliable, economical, and fast. However, operational instability from multiple interacting variables directly affects the mechanical integrity (MI) of these systems through internal and external corrosion (C). Addressing this problem increasingly relies on microscopic analysis (MA), image processing (IP), and artificial intelligence (AI). Together, these support a horizontal approach to reducing uncertainty and subjectivity in identifying, controlling, and monitoring corrosion-related risk factors. Following the PRISMA 2020 guidelines, this work presents a systematic literature review (SLR) of corrosion-related publications in oil and gas PTS spanning 1987–2025. From 1,085 records identified across two databases, 279 studies were retained after duplicate removal and quality assessment. Of these, 141 provide openly available data. A weighted evaluation matrix scoring twenty representative works against sixteen criteria across four thematic clusters—corrosion type, microscopy, image processing, and AI—shows that the number of jointly satisfied criteria ranges from 3 to 12 (mean 5.85 of 16). This indicates that integrated, multi-technique, AI-supported corrosion assessment remains uncommon across three decades of literature. Beyond consolidating the state of the art into a reusable evaluation instrument, this review establishes the theoretical and bibliometric foundation for an applied, multi-part research line that operationalizes several of these clusters on a real pipeline case study.

Abstract: The presence of iodine has been shown to enhance chalcopyrite leaching in ferric sulfate media. Previous studies of iodine-assisted heap leaching have demonstrated improved copper extraction from chalcopyrite. This study investigated the kinetics of iodine-assisted chalcopyrite leaching in ferric sulfate media under atmospheric stirred tank conditions. Thermodynamic analysis was first conducted to evaluate the stability of iodine species as a function of the ferric-to-ferrous ratio in sulfate media under the conditions investigated. Leaching experiments were performed in an iodine-resistant, fully sealed stirred glass reactor to minimize iodine loss through volatilization and prevent corrosion of reactor materials. Two chalcopyrite samples with distinct copper grades and mineralogical characteristics were used to evaluate the performance of iodine-assisted leaching under different leaching conditions. The experimental results show that the addition of 150 mg/L total iodide to a leaching solution containing an initial Fe(III)/Fe(II) ratio of 49 and a total iron concentration of 10 g/L at 85 °C achieved 96.5% copper extraction after 48 h. This represented an approximately 60% points increase in copper extraction compared with the corresponding test without iodide addition. In contrast to heap leaching, pyrite dissolution was observed during stirred tank leaching. Chalcopyrite leaching kinetics increased with increasing initial solution potential, initial iodide concentration, and temperature, up to a certain level. In addition, high copper dissolution rates were achieved by replenishing the system with fresh oxidant and by adding chloride to the sulfate media

Abstract: Because of the increasing demand for lithium, interest has grown in developing highly efficient methods to separate lithium from non-conventional sources such as lithium clays. This study assesses electrodialysis (EDU) and capacitive deionization (CDI), as well as a combined EDU–CDI method, for recovering and purifying lithium from a chloride-containing leachate solution obtained from lithium clays. This study examined the initial stage of the EDU process. Under different conditions (voltage, treatment time, and flow rates), the removal and enrichment of lithium, as well as its recovery and selectivity, were investigated. CDI was examined as a polishing technique, with particular attention to lithium recovery and discrimination between Li⁺ and Na⁺ ions using modified carbon-based electrodes. The results show that the EDU technique can promote lithium transport and enrichment; however, Li/Na selectivity remains low because the monovalent ions are transported simultaneously. The CDI technique has demonstrated a greater degree of lithium enrichment compared to that of Na⁺ ions, which shows its potential as a selective separation step. When combined, the techniques show complementary effects: EDU performs bulk ion separation, while CDI improves the quality of the lithium-enriched solution. Furthermore, preliminary tests have indicated promising behavior of the LiMn₂O₄-based electrodes.

Abstract: Scanning precession electron diffraction in transmission electron microscopy (TEM-SPED) enables highly accurate nanoscale orientation mapping and facilitates time-resolved tracking of microstructural changes, including grain boundary migration in polycrystalline metallic materials during isothermal or isochronal heat treatments. However, achieving full predicting grain boundary migration behavior requires further advances, including the integration of experimental observations with computational simulations. In this study, we addressed this challenge by directly assimilating TEM-SPED orientation maps into a multiphase-field model using an ensemble Kalman filter, wherein simulation parameters were iteratively updated to reproduce the experimental observations. The same field of view in a 50% cold-rolled pure-aluminum foil was repeatedly observed by TEM-SPED after successive ex situ isothermal annealing at 400 °C for up to 20 min at 5 min intervals. Through the assimilation process, grain boundary mobilities that reproduced the experimentally observed microstructural evolution were identified. A simulation restarted from the initial microstructure using the inferred mobilities achieved approximately 91% agreement with the experimental observations, suggesting that the inferred mobilities were suitable for predicting the observed microstructural evolution. These results demonstrate that the direct assimilation of nanoscale TEM-SPED observations improves the prediction of complex local grain boundary migration and enables the estimation of effective grain boundary mobilities.

Abstract: Balancing strength and ductility remains a central challenge in low-alloy Mg–Al–Ca–Mn alloys. In this study, a Mg–12Al₂Y master alloy was added to Mg–1.2Al–0.8Ca–0.4Mn to obtain nominal Al₂Y contents of 0, 1, 3, and 5 wt.%. The composites were prepared by stir casting and hot extrusion. In the as-cast condition, Al₂Y particles occurred both within α-Mg grains and in interdendritic regions; the 3 wt.% Al₂Y composite had the finest structure. Extrusion produced a bimodal microstructure of fine dynamically recrystallized (DRXed) grains and coarse unrecrystallized regions, and fragmented Al₂Y and Al₂Ca particles formed stringers along the extrusion direction. The 1 wt.% Al₂Y composite showed the highest tensile yield strength (346 MPa) and ultimate tensile strength (361 MPa), with an elongation of 5.8%. At 3 wt.%, the yield strength, ultimate tensile strength, and elongation were 316 MPa, 332 MPa, and 11.8%, respectively, representing the best strength–ductility balance among the compositions examined. Increasing the Al₂Y content to 5 wt.% raised the elongation to 12.6% but reduced the strength because of particle agglomeration and microstructural coarsening. The variation in mechanical response is discussed in relation to recrystallized grain size, retained deformation, texture, and particle distribution. Within the processing window examined here, master-alloy addition offers a practical route for controlling Al₂Y reinforcement in Mg–Al–Ca–Mn composites.

Abstract: The secondary dendrite arm spacing (SDAS) is a critical microstructural parameter that directly influences the local mechanical performance of AlSi casting alloys. Although the power-law relationship between cooling rate and SDAS is widely acknowledged, the existing literature lacks a standardized framework for selecting the most appropriate solidification thermal interval for calculating this characteristic cooling rate. This study introduces an optimized methodological approach by evaluating solidification kinetics across two distinct thermal regimes: a standard non-isothermal sand mold (no chill) and an accelerated cast iron insert configuration (with chill). Cooling curves of a primary hypoeutectic AlSi7Mg0.3 alloy were continuously recorded via ten calibrated K-type thermocouples along a wedge-shaped casting profile, and the corresponding local SDAS values were quantified using light optical metallography. By mathematically evaluating six distinct thermal analysis boundaries, the results demonstrate that conventional global intervals (e.g., liquidus-to-eutectic) yield lower predictive accuracy (R² ≈ 0.75) due to the accumulation of thermal "noise" from the early fluidic stage and the final eutectic reaction. In contrast, the localized interval bounded strictly between the Dendrite Coherency Point and the Rigidity Temperature (TDCP-TRigidity) achieved excellent correlation for both the baseline slow-cooling regime (R² = 0.8509) and the accelerated regime (R² = 0.9547). This optimized window successfully isolates the exact kinetic timeframe of secondary dendritic evolution and effectively eliminates localized calculation anomalies across the entire spectrum of cooling rates. Thermodynamic analysis reveals a sharp cooling asymmetry in the wedge geometry, where the local solidification timescale collapses by a factor of 34 at the chill base. This extreme kinetic restriction limits the characteristic solute diffusion distance(L≈D.t)) by a factor of nearly six, providing a quantitative physical basis for the significantly flatter coarsening slope (-14.85) under accelerated cooling compared to the baseline regime (-32.63), while simultaneously shifting the eutectic silicon morphology from coarse acicular plates to a highly refined, fibrous structure. The proposed methodology establishes a physically grounded, highly accurate microstructural prediction tool suitable for advanced foundry engineering and casting simulations.

Abstract: The growing use of binder jetting in foundry practice creates a need for effective recovery of the fine silica sand used in additively manufactured molds. This study compares mechanical and thermal reclamation of spent furfuryl-resin sands originating from binder-jetted molds (US-1) and conventionally manufactured molds (US-2) after ductile iron casting. Mechanical reclamation was conducted at rotor speeds of 280–560 rpm for 10–30 min, whereas thermal reclamation was performed at 600–1000 °C. Reclaim quality was assessed using loss on ignition (LOI), pH, dust generation, grain morphology, and bending strength. Conventional spent sand was more susceptible to mechanical treatment, reaching a maximum reclamation efficiency index of 41.1%, compared with 31.5% for binder-jetted sand. Thermal treatment was markedly more effective, reducing LOI to 0.14% for US-1 and 0.29% for US-2 and increasing reclamation efficiency to 94.8% and 89.8%, respectively. High-temperature thermal reclamation is therefore particularly suitable for fine-grained binder-jetted sand, whereas excessive mechanical treatment may promote grain crushing and dust formation.

Abstract: Diamond-like carbon (DLC) coatings are widely used to improve corrosion resistance, but the same coating can behave very differently depending on the metal substrate. This study focuses on how the substrate affects coating performance. Titanium-doped (Ti-DLC) and tungsten-doped (W-DLC) films were deposited by magnetron sputtering using the same process. Both were deposited on two substrates: 316L stainless steel and Ti6Al4V. The coatings were characterized by SEM, EDX, water contact angle, and Raman spectroscopy. Corrosion behavior was evaluated in 3.5 wt% NaCl by poten-tiodynamic polarization and electrochemical impedance spectroscopy (EIS). Wettability shifted in opposite directions on the two substrates: 316L became more hydrophilic after coating, while Ti6Al4V became more hydrophobic. Raman spectroscopy showed that the two dopants produced a similar degree of carbon disor-der on 316L, but diverged on Ti6Al4V. Ti-DLC was the most ordered film of the four coatings and W-DLC formed a more disordered one, suggesting that titanium and tungsten promote carbon ordering differently depending on the substrate. Both films reduced the corrosion current density compared to the bare metal. By EIS, every coated specimen also showed a higher polarization resistance than its bare substrate. On each substrate, Ti-DLC outperformed W-DLC, but with different degrees of improvement. On 316L, the less corrosion-resistant one, gained more from coating in relative terms, while Ti6Al4V reached the highest corrosion resistance. This substrate dependence likely reflects differences in dopant amount and interfacial bonding.

Abstract: This study investigates the fabricability, microstructures, mechanical and corrosion behavior of multi-material structure (MMS) composed of niobium alloy (NbZr1) and titanium alloy (Ti64) using a wire-arc directed energy deposition process. The microstructure of NbZr1 alloy primarily consisted of equiaxed grains oriented in the rolling direction, while the deposited Ti64 microstructure exhibited ‘banding’ morphology and a basket weave structure composed of α phase lamellae in a β matrix. The MMS interface revealed good metallurgical bonding and was free from defects such as cracks, pores and intermetallic phases. Niobium diffusion from the NbZr1 into the Ti64 alloy resulted in formation (β-Ti + Nb) solid solution which imparted strength to the MMS. The hardness testing showed that microhardness values follow the trend: NbZr1 substrate > MMS interface > Ti64 deposit. The NbZr1–Ti64 multi-material structure developed in this study exhibited a balanced combination of ductility (22.73% elongation) and moderate tensile strength (254.18 MPa), outperforming most reported NbZr1-Ti64 MMS studies. All tensile specimens failed in ductile manner on NbZr1 side. The MMS demonstrated superior corrosion resistance, exhibiting the lowest corrosion current density and corrosion rate compared to its individual counterparts.

Abstract: The ferromanganese industry, critical for global steelmaking, faces increasing pressure to adopt sustainable practices due to its high energy consumption and carbon footprint. High-carbon ferromanganese (HCFeMn) slag, a significant by-product, represents both an environmental challenge and a valuable resource for metal recovery. This study employs a multi-metric approach to assess the technical, environmental and operational performance of aluminothermic reduction smelting of HCFeMn slag in a 200 kW DC arc furnace, with focus on energy, material, and emissions assessment. For materials, the focus was on reductant efficiency, elemental accountability, elemental recovery, elemental deportment and slag-to-metal ratio. The environmental indicators studied includes CO2-equivalent emissions per ton of product, dust and particulate emissions, NOx/SOx emissions. The consumption of electrodes and refractory was also studied. The innovative process proposed in this study also aims to valorize metallurgical residues into high-value manganese alloy products while minimizing environmental burdens. A total of 2009 kg of HCFeMn slag was smelted and reduced by recycled aluminium scrap (202 kg) over 20 taps, while fluxing with burnt lime (382 kg). The campaign recorded an average gross specific energy requirement of 0.87 kWh kg−1 of charge across 20 taps, with tap-by-tap values ranging from 0.74 to 0.98 kWh kg−1. When compared to conventional submerged-arc SiMn furnaces ( 4,000–4,500 kWh t−1), this corresponds to an approximate 79–81 % reduction in specific energy consumption. The attained aluminium reductant efficiencies ranged from 55.14 to 91.89 % (the campaign average being ∼60 %), with Mn recovery of 47–81 % and Fe recovery progressing from 33–38 % to over 90 % across successive taps. The observed high slag-to-metal ratio (SMR) (4.79–6.68 kg/kg) is attributed to the operating strategy of using slag as a feed, rather than a process deficiency. This high SMR contrasts with the 1.0–1.3 kg/kg typical of SiMn industrial operations. The emissions from the current 200 kW DC arc furnace study were approximately 1.35 t CO2-eq t−1 alloy (Eelec=1.20 t CO2-eq t−1; EAl−prod=0.15 t CO2-eq t−1), marking a decrease of 60–65 % when compared to conventional carbothermic HCFeMn production (3.0–4.0 t CO2-eq t−1) and an 80 % decrease when compared with the full cradle-to-gate SiMn benchmark (6.94 t CO2-eq t−1). Direct process CO2 emissions were negligible, owing to the absence of fossil reductants in the burden. SO2 emissions of 0.312 kg t−1 alloy and particulate emissions of 10.4 kg t−1 alloy (pre-abatement) were measured, well below industrial SiMn off-gas emission intensities, while the use of recycled scrap aluminium, which requires up to 95 % less energy than primary aluminium, underpins the low embodied-carbon contribution. The integration of aluminothermic reduction in a DC arc furnace offers a robust, efficient and environmentally sustainable alternative route for the recovery of manganese from industrial HCFeMn slag, validating the current-study process at Technology Readiness Level 6. The primary contribution of this study is the application-level demonstration of the current process at a 200 kW DC arc furnace pilot scale, and bridging the gap between laboratory concepts and industrial-scale implementation. The study further compares the Pyrosim simulation values to campaign data, slag and alloy chemical analyses and specific energy requirement.

Abstract: The high-speed steel (HSS) substrate was coated with CrC, NbC, TiC, and VC layers using the thermo-reactive diffusion (TRD) process at 900 and 1100 °C for 2 and 4 hours. The experimental design was implemented according to the Taguchi L8 orthogonal array. The coating morphology was examined by scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), while the phase composition was identified by X-ray diffraction (XRD). The effects of coating type, temperature, and time on coating thickness, microhardness, coefficient of friction, and specific wear rate were evaluated using analysis of variance (ANOVA). SEM and EDS analyses showed that coatings produced at lower temperatures and shorter times exhibited non-uniform layer thickness, localized porosity, and irregular carbide formation, whereas coatings applied at higher temperatures and longer times resulted in uniform layers, homogeneous elemental distribution, and improved surface morphology. XRD analyses confirmed that the coatings consisted of high-intensity carbide phases and that the chemical composition of the substrate influenced the resulting coating phases. Phase composition analysis revealed the presence of residual phases such as Cr₇C₃ and Cr₂₃C₆ in the coatings. Coating thickness and hardness increased with increasing temperature and time. Analysis of variance revealed that coating type (45.13%) and temperature (42.34%) were the dominant factors affecting coating thickness, whereas temperature (39.92%) and coating type (37.77%) had the greatest contributions to hardness. The friction coefficient was predominantly influenced by coating type (87.98%), whereas the specific wear rate was mainly affected by temperature (34.99%) and coating type (33.37%). NbC coatings exhibited the lowest performance among the investigated coatings across all evaluated properties.

Abstract: Laser powder bed fusion (LPBF) enables fabrication of complex bimetallic structures, such as combustion chambers, that require a thermally conductive internal channel supported with a high-strength structural jacket. Inconel625 (IN625) served as the substrate, with GRCop-42 deposited with varying laser power and laser scanning speeds to create the IN625-GRCop-42 interface. Hot isostatic pressing (HIP) was performed to evaluate defect mitigation and Vickers microhardness testing assessed the mechanical properties across the bimetallic interface. Microstructure characterization revealed porosity across the full processing window and HIP was unsuccessful in eliminating the defects, indicating that densification is primarily achieved by LPBF process optimization. Microhardness testing proved that the as-printed samples showed higher microhardness values than the as-HIPped samples due to the fine microstructure, high dislocation density and residual stresses caused by the LPBF process. As-HIPped samples showed recrystallization and grain coarsening due to the decrease in microhardness compared to the as-printed samples. These results highlight the importance of LPBF process optimization in achieving strong, thermally stable IN625-GRCop-42 bimetallic interfaces. This study aims to investigate the microstructural and mechanical behavior of the IN625 and GRCop-42 dissimilar metal interface fabricated using the LPBF process and the effects of HIP on the bimetallic microstructure.

Abstract: This study develops novel multicomponent Al–Mg–Si–Zr–Cu-based alloys for high-pressure die casting (HPDC) with improved mechanical properties and thermal sta-bility. Four compositions were designed through Zn and Cr additions, supported by thermodynamic modelling. Phase formation and microstructure were analysed by XRD and SEM/EDS, while density, electrical conductivity, hardness, and mechanical behaviour under tensile and compressive loading at room temperature and 200 °C were evaluated. Hardness increased from 166 to 214 HV3 with Zn and Cr due to the formation of complex intermetallic phases. The Al–Mg–Si–Zr–Cu alloy showed the best balance of strength and ductility under tensile loading, whereas Zn and Cr additions reduced tensile performance. In compression, Zn significantly improved strength, reaching an ultimate compressive strength of 697 MPa. Compared with the reference AlSi9Cu3 alloy, the new alloys achieved up to 30% higher yield strength, 13% higher ultimate tensile strength, and im-proved thermal stability. Among the studied compositions, Al72Mg10Si5Zr3Cu10 showed the best overall performance, while Al67Mg10Si5Zr3Cu10Zn10 was optimal for compres-sion-dominated applications.

Abstract: The empirical descriptors of high-entropy alloys and oxides, from the mixing entropy and atomic-size mismatch to the Miedema enthalpies and the Ω, Φ, and φ stability parameters, are quoted in nearly every design study, yet they are reimplemented ad hoc by individual groups, by closed web calculators, and now inside language-model agent frameworks, where fabrication of property values is a documented failure mode. The resulting numbers disagree and cannot be traced or reproduced. We present HEA-Bench, an open calculator in which every descriptor is a closed-form expression over a curated, literature-cited element-property table, with the six canonical phase-prediction rules reported alongside their thresholds and sources rather than as predictions. One calculation core is delivered as a dependency-free Python library, a zero-install browser application, an offline desktop executable, and a Model Context Protocol server that exposes it to AI agents as deterministic tools, returning every value with its unit, citation key, and version so an agent’s reasoning trace can be audited. The implementation reproduces published per-alloy and per-oxide anchor values to their printed precision and extends to high-entropy oxides in four structure families. The numerical instability of Ω near zero mixing enthalpy is quantified and exposed as a callable check.

Abstract: Neodymium (Nd) and dysprosium (Dy) are two critical rare earth elements for fabricating NdFeB permanent magnets, which have crucial applications in modern technologies. The increasing global demand for Nd and Dy emphasizes new efficient processes for their recovery and purification, which are technologically challenging due to their close physical and chemical properties. Through systematic exploration, it was found that Lewatit VP OC 1026 resin impregnated with di-(2-ethylhexyl) phosphoric acid (D2EHPA) had a strong adsorption preference for Dy³⁺ over Nd³⁺, which is highly suitable for Dy-Nd separation from their mixed solutions under optimized conditions. The loaded resin could be eluted using dilute sulfuric solutions for recycling to the adsorption process. By employing a multistage adsorption-elution process analogous to distillation, efficient Dy-Nd separation and purification were realized from their mixed solution, with a prospective purity of 99.13% and recovery of 97.45% for Dy and a prospective purity over 99.96% and recovery of above 99.90% for Nd, despite the large concentration disparity between Dy and Nd where Nd concentration is over 26 times of that of Dy. This research demonstrates that efficient recovery and purification of metals from aqueous solutions can be achieved using selective resin adsorption processes analogous to distillation, despite large concentration differences of the metals in the solutions, which presents new alternative approaches.

Abstract: Metallic powder systems containing niobium play a key role in the development of advanced materials for structural, biomedical, energy, and surface-engineering applications. The incorporation of niobium into metallic powders influences particle behavior during processing, phase stability, microstructural evolution, and the resulting mechanical and corrosion properties of consolidated materials. This review examines the scientific and technological advances related to niobium-containing metallic powders, covering powder production routes, particle characterization methods, processing techniques, and performance evaluation. Publications on powder metallurgy, additive manufacturing, thermal processing, surface modification, and corrosion-resistant materials were analyzed to identify relationships among powder characteristics, processing conditions, and material performance. The available evidence indicates that niobium contributes to grain refinement, precipitation control, microstructural stabilization, improved resistance to wear, and localized corrosion. The element also expands the applicability of metallic powders in functional coatings, biomaterials, engineered surfaces, and components manufactured from particulate feedstocks. Current challenges involve powder homogeneity, process reproducibility, economic considerations, and the prediction of long-term service behavior. The analysis highlights niobium's contribution to the design of high-performance metallic powder systems and identifies research directions for developing materials with enhanced reliability and industrial applicability.

Abstract: A study was conducted to characterize the performance of a HydroFloat® coarse particle flotation (CPF) cell using rougher tailings samples from an industrial copper mining operation. The work involved measuring internal hydrodynamic variables under a wide range of operating conditions. The effect of different operational and hydrodynamic conditions on the metallurgical performance of the HydroFloat® cell was also evaluated. Gas dispersion measurements, such as bubble size distribution, superficial gas velocity (J$_g$), superficial area flux (Sb), and residence time distribution (RTD), were recorded, enabling a detailed analysis of the cell's operation. Results show that copper recovery is strongly influenced by the superficial gas velocity (J$_g$) and the superficial liquid velocity (J$_l$). It was observed that the bubble diameter (d$_{32}$) remained relatively constant at 0.5 mm across all operating conditions, which is well below typical bubble sizes for conventional flotation cells. This suggests that contrary to what may be expected, in this kind of machine, small bubbles are able to float coarse particles. Bubble image inspection suggests that the HydroFloat{\textregistered} cell creates conditions conducive to bubble-particle aggregates, which would explain how small bubbles can float coarse particles. This study contributes to the understanding of CPF and establishes a framework for optimization in copper concentrators.

Abstract: One of the most common ways to improve the properties of aluminum casting alloys is through their modification. This study investigates the influence of titanium modification on the mechanical properties of Al-Si casting alloys. In this research, the Al-Si alloy which is widely used in the foundry industry, was selected as an object. The samples were liquefied in an induction furnace, and the liquid alloy was poured into sand-clay molds. The casting temperature was 750 °C. The titanium element was added to the liquid Al-Si foundry alloy in special packaging in the form of a powder from 0.1% to 0.3% of the charge and in the form of Al-10Ti master alloy from 0.1% to 0.2%. Then, samples were machined to prepare further investigations. During the research, mechanical properties including hardness and wear resistance analysis were conducted. Moreover, X-ray diffraction and microstructural analysis of the Ti modified Al-Si samples were carried out. Experimental results showed that the addition of titanium improved the mechanical properties of the samples. That is, the highest hardness was obtained at 0.1 wt.% Ti modified Al–10Ti master alloy, while titanium powder resulted in a more gradual increase in hardness. According to the wear resistance evaluations, addition of titanium within the range of 0.1–0.2 wt.% content was performed an optimal result. After, microstructural analysis, it is found that titanium promoted grain refinement and improved structural homogeneity, especially it is added in the form of Al-10Ti master alloy. The introduction of titanium into the aluminum alloy led to the formation of the Al₃Ti intermetallic compound, which contributed to the improvement of mechanical properties. These results demonstrate that the modification of Al–Si alloys with titanium can be reliably used to predict and improve mechanical properties based on comprehensive experimental analysis.