Abstract: Since its introduction, focused ion beam (FIB) technology has expanded from micro/nanofabrication in the semiconductor industry into the field of multimodal characterization of metallic material microstructures. This article systematically reviews the latest research advances of FIB-SEM technology in the field of metallic materials science. The fundamental principles and system functions of FIB-SEM are introduced, with emphasis on its key applications in two-dimensional and three-dimensional morphological characterization, as well as specimen preparation for transmission electron microscopy (TEM) and atom probe tomography (APT). The combined strategies of FIB-SEM with electron backscatter diffraction (EBSD), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and other characterization techniques are also discussed. Current developments indicate that FIB-SEM technology is advancing toward multi-ion-source synergy and multimodal integration. In the future, combined with artificial intelligence and big data analysis, it is expected to enable high-throughput, correlative measurements of multidimensional properties at the micro-scale, providing important technical support for "materials genome" research in metallic materials.

Abstract: Copper anodic slime is a valuable secondary resource for precious and critical elements such as gold, silver, selenium, and tellurium. In certain industrial flowsheets, copper anodic slime is smelted together with lead to facilitate silver and gold recovery, generating a fine lead‑rich fly ash as a secondary residue. This dust contains considerable amounts of selenium and tellurium and poses significant environmental and occupational health risks due to its high lead content and sub‑micron particle size. The present study investigates sodium carbonate (Na₂CO₃) leaching as an environmentally benign pre‑treatment approach aimed at partial removal of selenium and tellurium while simultaneously stabilizing lead through carbonate formation. Rather than targeting maximum metal recovery, the process is evaluated from a detoxification‑oriented perspective suitable for safer disposal or downstream recycling of hazardous metallurgical dusts. The effects of sodium carbonate concentration, temperature, solid‑to‑liquid ratio, and leaching time on selenium and tellurium recovery were investigated using a central composite design (CCD) implemented in Design‑Expert software. Under the investigated conditions, selenium recovery reached a maximum of 53.9%, while tellurium recovery remained generally below 15%, with a maximum observed value of approximately 33.9% in a specific experimental run. Scanning electron microscopy revealed that the dust consists primarily of semi‑spherical and elongated particles, with lead carbonate precipitation occurring preferentially on particle surfaces during leaching. Energy‑dispersive spectroscopy confirmed the conversion of lead sulfate phases to lead carbonate, which progressively limited further selenium and tellurium dissolution. A brief kinetic analysis indicated that selenium dissolution follows a mixed control regime involving surface chemical reaction and diffusion through product layers, whereas tellurium leaching did not exhibit consistent kinetic behavior across the studied conditions. The results demonstrate that sodium carbonate leaching can effectively reduce the mobility of selenium and tellurium while stabilizing lead, supporting its application as a detoxification‑oriented pre‑treatment for lead‑rich metallurgical dusts rather than a conventional high‑recovery extraction process. Furthermore, thermodynamic analysis confirmed the environmental detoxification of the residue through the stable immobilization of lead as cerussite (PbCO3). The macroscopic dissolution behavior was successfully described using an apparent Shrinking Core Model (SCM), revealing the interactive effects of leaching parameters on the kinetic bottlenecks.

Abstract: Resistance spot welding of dissimilar steels is a key Linkage process in the manufacturing of rail passenger car bodies. However, there are problems such as core deviation caused by material physical property differences in the welding of dissimilar steels (stainless steel/low-carbon steel). This study improves the weldability of stainless steel and low-carbon steel by adding a nickel intermediate layer between them. The results show that adding a nickel intermediate layer can Valid compensate for heat Loss, suppress the deviation of the weld nucleus, optimize the size of the weld nucleus, and improve the Stability of the welding quality.

Abstract: Machine learning interatomic potentials (MLIPs) are typically constructed for homogeneous crystalline systems that exhibit only minimal local deviations from equilibrium configurations. However, substitutional alloying elements in multicomponent engineering alloys are often distributed in a locally heterogeneous form. To address this, we develop a fine tuned MLIP based on the MACE foundation model, specifically tailored for Mo based dilute alloys containing one or two out of 20 substitutional elements: Cr, Fe, Mn, Nb, Re, Ta, Ti, V, W, Y, Zr, Al, Zn, Cu, Ag, Au, Hg, Co, Ni, and Hf. The model is trained on more than 7,000 non equilibrium structures derived from first principles density functional theory (DFT) calculations. The optimized large scale fine tuned model attains state of the art accuracy, with mean absolute error (MAE) and root mean square error (RMSE) of 2.27 meV/atom and 3.79 meV/atom for energy predictions, and 13.83 meV/Å and 24.26 meV/Å for force predictions, respectively. Systematic evaluation of model transferability to unseen alloying elements under different data splitting protocols demonstrates that incorporating even a modest set of new element DFT data during refinement reduces the energy MAE below ~20 meV/atom. The fine tuned models reduce the MAE by approximately 7–10 times compared to models trained from scratch, and by 10–20 times relative to zero shot foundation models. This performance gain remains consistent across varying dataset sizes (equilibrium vs. non equilibrium structures) and model scales. Our work illustrates the efficacy of transfer learning from globally homogeneous systems to locally heterogeneous multi element alloy environments, delivering a robust MLIP tool for the accelerated design of multicomponent alloys.

Abstract: This paper investigates the formation mechanism and key influencing factors of freckle defects that arise during the directional solidification of a novel third-generation nickel-based single crystal superalloy turbine blade. A combined experimental and multi-physics numerical simulation approach was adopted. The results reveal that freckle formation primarily results from the coupling effect of solute segregation and thermo-solutal convection during solidification, leading to dendrite fragmentation and subsequent aggregation of equiaxed grains. The resultant density inversion drives upward interdendritic flow, which plays a dual role: it promotes remelting and fragmentation of secondary dendrite arms, while simultaneously opening solute-enriched preferential flow channels that eventually develop into freckle defects. The severity of freckling is closely dependent on both the casting's position within the furnace and its local geometric characteristics. Castings located in regions with poorer heating conditions experience lower temperature gradients and slower solidification rates, significantly increasing their susceptibility to freckle formation. Similarly, on a given casting, the side subjected to less favorable heating is more prone to freckle initiation. This work provides a crucial theoretical foundation for understanding freckle formation in nickel-based single crystal superalloys and offers practical guidance for optimizing blade manufacturing processes, reducing solidification defects, and enhancing blade quality and service performance.

Abstract:

This study systematically investigates the effects of the final annealing temperature on the microstructural evolution and mechanical properties of an Al-Fe-Si alloy aluminum foil. Scanning electron microscopy (SEM) characterization and tensile tests are employed for analysis. As the annealing temperature is elevated from 240°C to 360°C, the average grain size increases monotonically from 5.2 μm to 9.6 μm. Continuous recrystallization is identified as the predominant grain growth mechanism.Tensile deformation exhibits the homogeneous-plastic behavior without localized necking. The tensile strength decreases significantly in the range of 240–300°C and subsequently undergoes a recovery stage at 300–360°C. The Pronounced elongation anisotropy is observed. The maximum elongation reaches 30–34% along the 45° direction relative to the rolling direction (RD), which is approximately 1.5 times that along the RD (0°).Comparative analysis of the anisotropy indices demonstrates that the aluminum foil annealed at 240°C achieves the minimal tensile strength anisotropy (13.0 MPa) and elongation anisotropy (−4.2%). This indicates optimal comprehensive mechanical performance.These findings provide a theoretical rationale for the industrial optimization of the annealing processes for Al-Fe-Si alloy foils. They are particularly valuable for balancing microstructural regulation and mechanical property enhancement in lithium-ion battery soft-packaging applications.

Abstract: This study systematically investigates the influence of annealing time on the microstructure and mechanical properties of a (CoCrNi)₉₃.₅Al₃Ti₃C₀.₅ medium-entropy alloy. Following hot rolling, the alloy was subjected to annealing treatments at 900°C for 10 min (HA900-10) and 60 min (HA900-60). Microstructural characterization revealed that both alloys contained three types of precipitates: intergranular M₂₃C₆ and MC-type carbides, as well as γ′ phase. The HA900-10 specimen exhibited a low degree of recrystallization, whereas prolonged annealing promoted partial recrystallization, leading to the formation of a slightly heterogeneous structure (HA900-60). Additionally, the extended annealing facilitated the intragranular precipitation of nanoscale γ′ phase. Room-temperature tensile tests demonstrated the HA900-10 and HA900-60 specimens achieving yield strengths of 1276 MPa and 1202 MPa, with total elongations reaching 26% and 28%, respectively. Quantitative strengthening analysis indicated that the strength of HA900-10 primarily originated from dislocation and grain boundary strengthening. For HA900-60, an additional significant contribution arose from the dislocation shearing mechanism induced by the intragranular γ′ precipitates. Analysis of the deformation mechanisms revealed that planar slip, assisted by the formation of stacking faults, dominated the room-temperature deformation, thereby ensuring sustained work-hardening capacity. This research provides a theoretical foundation for tailoring the microstructure and properties of multi-phase medium-entropy alloys through annealing process control.

Abstract: A Ti6Al4V alloy fabrication via laser powder bed fusion (L-PBF) leads to the formation of coarse columnar β grains that give rise to anisotropic mechanical properties and inadequate strength. Incorporating the rare earth oxide, yttrium oxide (Y₂O₃), has proven an effective strategy in enhancing the mechanical performance of Ti6Al4V al-loys. This study systematically investigates the effects of various Y₂O₃ contents on the microstructure and mechanical properties of Ti6Al4V alloys fabricated via L-PBF. The results demonstrate that a Y₂O₃ addition of 0.2 wt.% produces β grains and α phases with average sizes of 61.6 and 7.6 μm, respectively. Transmission electron microscopy observations reveal that Y₂O₃ nanoparticles, together with elemental Y nanoparticles formed by reduction, are distributed both within the α-Ti matrix and along phase boundaries. This distribution effectively reinforces grain boundaries and promotes heterogeneous nucleation, thereby refining the microstructure. Mechanical property tests indicate that the alloy strength significantly improves as the Y₂O₃ content in-creases. Specifically, the alloy with 0.2 wt.%Y₂O₃ exhibits a tensile strength of 1106 MPa, a yield strength of 1074 MPa, and an elongation of 10.0%. This study proposes an in-novative rare earth strengthening method for refining the microstructure of L-PBF-fabricated titanium alloys and comprehensively enhancing their mechanical properties.

Abstract:

Hydrometallurgical pretreatment of pyrite-bearing concentrates and tailings by hydrothermal interaction with Cu(II) solutions is a promising route for chemical beneficiation and mitigation of acid mine drainage but is limited by passivation caused by elemental sulfur and secondary copper sulfides. Here, the effect of sodium lignosulfonate (SLS) on the hydrothermal reaction between natural pyrite and CuSO₄ in H₂SO₄ media at 180–220 °C was studied at [H₂SO₄]₀ = 10–30 g/dm³, [Cu]₀ = 6–24 g/dm³ and [SLS]₀ = 0–1.0 g/dm³. Process efficiency was evaluated by Fe extraction into solution and Cu precipitation on the solid phase, and products were characterized by XRD and SEM/EDS. SLS markedly intensified pyrite conversion: at 200 °C and 120 min Fe extraction increased from 14 to 26 % and Cu precipitation from 5 to 23 %, while at 220 °C Fe extraction reached 33.4 % and Cu precipitation 26.8 %. XRD confirmed the sequential transformation CuS → Cu_1.8S. SEM/EDS showed that SLS converts localized nucleation of Cu_xS on defect sites into the formation of a fine, loosely packed and well-dispersed copper sulfide phase. The results demonstrate that lignosulfonate surfactants efficiently suppress passivation and enhance mass transfer, providing a basis for intensifying hydrothermal pretreatment of pyrite-bearing industrial materials.

Abstract: Owing to the superior reduction kinetics of limonite and goethite relative to silicates, coupled with the poor beneficiation performance of saprolite-type laterite, the direct carbothermal reduction of saprolite-type laterite exhibits limited nickel selectivity. This study leverages the selective oxidation effect of CO-CO2 atmosphere on metallic iron and its suppression of Fe2+ reduction to promote iron migration from oxides into the silicate phase, achieving homogenization and thereby negating its kinetic advantage in reduction. Parameter optimization experiments revealed that treating pre-reduced minerals with a 30 vol% CO atmosphere at 1200 °C for 20 minutes achieves complete iron homogenization within the silicate phase. Compared with the nickel-iron alloy (containing less than 10 wt% Ni) obtained via RKEF process, the combination of pre-reduction, CO-CO2 treatment, and melting reduction process yielded nickel-iron alloys with nickel contents of 52.1 wt% (FeNi50 alloy) and 64.2 wt% at carbon consumptions of 4.0 wt% and 3.83 wt%, respectively, accompanied by nickel recovery rates of 95.5% and 91.2%. Furthermore, the enrichment of Fe2+ in the slag significantly reduces its melting point to approximately 1450 °C, enabling complete slag-metal separation after smelting at 1550 °C for 10 minutes.

Abstract: The paper focuses on materials characterization and «in vivo» biocompatibility tests of Ti6Al7Nb alloys microdoped by 0.3 wt. % of rareearth elements (REE) to use it as perspective materials to produce personalized medical implants. All Ti6Al7Nb0.3REE alloys (REE Y, Ce, La) were produced by electric arc melting method and characterized by scanning electron microscopy (SEM), optical microscopy (OM), energy-dispersive Xray spectroscopy analysis (EDX), helium pycnometer as well as reducing/oxidation melting methods. The measured true densities increased in the order: Ti−6Al−7Nb−0.3Y (4.4563 ± 0.1075 g/cm³) < Ti−6Al−7Nb−0.3Ce (4.7255 ± 0.2853 g/cm³) < Ti−6Al−7Nb−0.3La (4.8019 ± 0.0111 g/cm³). Diffraction analysis was performed to indicate phases composition and calculate crystallites sizes, crystal orientation and lattice parameters that confirmed REEmicrodoping due to increase of lattice volume. The single-phase Ti6Al7Nb0.3Y alloy had the finest αTi crystallites (22.32 nm), the larger αTi crystallites in the dualphase Ti6Al7Nb0.3Ce and Ti6Al7Nb0.3La (30.77 nm and 29.83 nm, respectively) suggest that the presence of the βTi phase. Hardness (H) and elastic modulus (E) were indicated by nanoindentation and increased in the order: Ti−6Al−7Nb−0.3La (4.01 GPa and 17.7 GPa respectively) < Ti−6Al−7Nb−0.3Y (4.39 GPa and 137 GPa respectively ) < Ti−6Al−7Nb−0.3Ce (4,67 GPa and 146 GPa respectively). In vivo tests showed that Ti6Al7Nb0.3La alloy had statistically significant increase of local inflammation at the one-week mark needed to further research and explanation as well, that could be indicator of toxicity in comparison with other studied alloys.

Abstract: Al–Zn–Ca alloys are good candidates for industrial electronics and electric vehicles due to their high thermal conductivity, castability, and corrosion resistance, but their strength requires improvement. This study investigates how Sc and Zr additions affect the microstructure, thermal, mechanical, and corrosion properties of an Al–3wt%Zn–3wt%Ca base alloy. Microstructural analysis showed that substituting Sc with Zr did not drastically alter the phase composition but changed the elemental distribution: Sc was uniform, while Zr segregated to dendritic cores. Zr addition also refined the grain size from 488 to 338 μm. An optimal aging treatment at 300 °C for 3 hours was established, which enhanced hardness for all alloys via precipitation of Al3Sc/Al3(Sc,Zr) particles. However, this Zr substitution reduced thermal conductivity (from 184.7 to 168.0 W/mK) and ultimate tensile strength (from 269 to 206 MPa), though it improved elongation at fracture (from 4.6 to 7.1%). All aged alloys exhibited high corrosion resistance in 5.7% NaCl + 0.3% H2O2 solution, with Zr-containing variants showing a lower corrosion rate and better pitting resistance. The study confirms the potential of tuning Sc/Zr ratios in Al–Zn–Ca alloys to achieve a favorable balance of strength, ductility, thermal conductivity, and corrosion resistance.

Abstract: To reveal its influence on quasicrystal structure analysis, multiple diffraction (MD) effects in a basic Co-rich decagonal Al-Co-Ni quasicrystal have been investigated in-house and with synchrotron radiation. Two weak reflections were chosen as the main reflections (P) in the in-house measurements and 40° ψ-scans of one main reflection have been performed with synchrotron radiation. As well known for periodic crystals and the i-quasicrystal, it is also observed for this d-quasicrystal that the intensity of the main reflection may significantly increase if the simultaneous (H) and the coupling (P-H) reflections are both strong. The occurrence of MD events during collection of a full data set as well as the ψ-scans measurements have been studied based on an average structure model and the kinematical MD theory.

Abstract: The tracer diffusion of aluminium in the CuCr1Zr alloy was investigated, a material widely employed as an electrode in resistance spot welding. As a tracer layer, an alloy of Cu – 8.8 at.% Al was used, which was deposited by ion-beam sputtering. Isothermal diffusion annealing experiments were carried out between 500 and 700 °C, at temperatures relevant for industrial welding conditions. Al depth profile analysis was done by Secondary Ion Mass Spectrometry. The results revealed that aluminium exhibits a temperature-dependent diffusion behaviour. The diffusivities can be fitted together with literature data on Al diffusion in pure Cu obtained at higher temperatures according to the Arrhenius law. An activation enthalpy of 2 eV is obtained. The influence of a surficial oxide layer on the diffusion process is discussed.

Abstract: This study presents the first metallurgical analysis of twenty-five votive statuettes of Hercules from the National Archaeological Museum of Campobasso, Molise, Italy. These artifacts, which have previously been unexamined from a metallurgical perspective in the region, were analyzed to understand their composition, manufacturing techniques, and current state of preservation. All the samples were first analyzed in situ using X-ray fluorescence (XRF) and then were sampled to conduct microstructural analyses on polished cross-sections by optical and scanning electron microscopy. The statuettes revealed a ternary Cu-Sn-Pb alloy, consistent with historical alloying practices and manufacturing techniques typical of the period. The study highlights a homogeneous biphasic microstructure with dispersed lead nodules within the bronze matrix. The corrosion products on the surface have peculiar colors and textures due to both the finishing process and the alteration accord over centuries of abandonment, aiding the understanding of the material's behavior over time. The compositional results confirm the usage of materials and techniques in line with other coeval artifacts. Additionally, corrosion studies using Raman spectroscopy and the reproduction of the statuettes through casting will be conducted to develop a conservation protocol, to create inclusive displays for museum audiences.

Abstract: The paper presents the detailed comparisons of solute macro-segregation pictures predicted by different meso-macroscopic simulations, based on the single domain enthalpy-porosity approach coupled with distinct models of flow resistance in the two-phase zone. In the first, the whole zone is treated as a Darcy's porous medium (EP model); in the other two, the columnar and equiaxed grain structures are distinguished using either the coherency point (EP-CP model) approach or by tracking a virtual surface of columnar dendrite tips (EP-FT model). The simplified 2D model of a solidifying cast in a centrifuge is proposed, and calculations are performed for the Pb-48%wt Sn cast at various hyper-gravity levels and rotation angles. It is shown that the predicted macro-segregation strongly depends on the mesoscopic model used, and the EP-FT simulation (validated with the AFRODITE benchmark) provides the most realistic solute inhomogeneity pictures. The EP-FT model is further used to investigate the impact of the hyper-gravity level and the cooling direction on the compositional nonuniformity developing in centrifuge casting. The hyper-gravity level visibly impacts the macrosegregation extent. The region of almost uniform solute distribution in the slurry zone rises with the increased effective gravity, though the solute channeling is more severe for higher gravity and rotation angles. A-channeling and V-channeling were observed for angles between the gravity vector and cooling direction lower than 120° and higher than 120°, respectively.

Abstract: This work examines how rolling speed, feeding rate, and pass schedule—with a constant total reduction—affect the stress–strain fields, rolling force, and texture evolution of Al–Cu–Sc alloy sheets. A coupled finite element (FEM) and viscoplastic self-consistent (VPSC) framework is employed and compared with EBSD measurements to connect macroscopic fields with microscale texture changes. Results indicate that increasing rolling speed raises the effective strain rate and deformation heating, which lowers peak rolling force and improves in-plane stress homogenization on the RD–ND plane, while enhancing surface–core incompatibility and residual-stress gradients along the ND–TD direction. A higher feeding rate mainly intensifies work hardening, slightly elevates rolling force, and promotes near-surface stress/strain localization; in contrast, multi-pass schedules redistribute deformation between passes and reduce macroscopic stress concentration. Texture analyses show a speed-induced rotation from 〈001〉 toward 〈111〉 orientations, strengthening shear-related components; KAM maps suggest increased local orientation gradients consistent with higher stored energy. The simulations capture the principal experimental trends across conditions, supporting the use of the combined framework for trend-level process guidance. Overall, the findings clarify parameter–microstructure relationships and provide a basis for designing rolling routes that balance force reduction, stress uniformity, and texture control in Al–Cu–Sc sheets.

Abstract:

The adoption of advanced high-strength steels (AHSS) in the automotive industry have significantly increased in recent years driven by weight reduction and enhanced crashworthiness. Hot dip galvanised sacrificial coatings are regularly applied to these steels for corrosion protection. In this investigation, the scanning vibrating electrode technique (SVET) demonstrated that hydrogen evolution on the steel substrate is taking place when these sacrificial coatings are damaged during service, increasing the risk of hydrogen embrittlement. The hydrogen embrittlement susceptibility of a new generation of nano-precipitate ferritic, FNP, AHSS have been studied and compared against conventional dual phase ferritic-martensitic, FM, AHSS at equivalent strength levels. Hydrogen permeation tests have shown that FNP AHSS have lower effective diffusion coefficients, Deff, than FM AHSS at equivalent strength levels. At 800 MPa strength level D_eff were 1.68×10^-7 cm²/s and 1.87×10^-7 cm²/s for FNP800 and FM800 respectively. At higher strength levels, 1000 MPa, D_eff were 7.45×10^-8 cm²/s and 1.45×10^-7 cm²/s for the FNP1000 and FM1000, respectively. Slow strain rate tests (SSRT) showed that FNP AHSS displayed over 35% higher resistance to hydrogen embrittlement than conventional FM AHSS. Quantitative fractographic analyses confirmed that the new ferritic nano-precipitate microstructure retains much more ductile behaviour than conventional martensitic-ferritic even under the most severe hydrogen charging conditions tested.

Abstract: This study investigates the effects of Ti addition on the microstructures, melting temperature ranges, thermal expansion behavior, high temperature creep and oxidation resistances of an equimolar CoNiFeCr alloy of a foundry origin. 1.5 wt.% Ti added did not really change the single–phased state of the reference quaternary alloy but induces a significant decrease of the melting start and melting end temperatures. The thermal expansion coefficient is slightly lowered only while the creep resistance at 1100°C is significantly enhanced. The oxidation at 1200°C is controlled by species diffusion through a continuous chromia layer and the parabolic constant is higher than for the quaternary alloy, due to external and internal Ti oxidation. The presence of a thin layer of titanium oxide covering the chromia scale is suspected to limit chromia volatilization and scale spallation at cooling. Globally Ti demonstrated a globally beneficial influence of the high temperature properties of the alloy.

Abstract: The transition from regular to anomalous eutectic structures critically impacts the mechanical properties of eutectic alloys. This study investigated the non-equilibrium solidification behavior of Ni-Sn alloys using Bridgman directional solidification coupled with Cellular Automaton (CA) simulations. Unlike deep undercooling methods, this approach can offer a solution by decoupling temperature gradient and growth velocity during the solidification process, revealing that anomalous eutectic formation occurs specifically at growth velocity transition zones, not during steady-state growth (0.1–2000 μm/s). CA simulations confirmed that velocity jumps destabilize regular lamellae, the Ni3Sn phase epitaxially grows along the substrate in a cellular manner, triggering independent α-Ni nucleation followed by Ni₃Sn encapsulation. This work identifies a distinct process window for anomalous eutectic formation and elucidates its decoupled nucleation mechanism, advancing non-equilibrium solidification theory.