To enhance the mechanical bonding performance of solderable polymer composites (SPCs) containing low-melting-point solder (LMS) and high-melting-point solder (HMS) fillers (LH-SPCs), a novel Cu-reinforced LH-SPC (Cu-LH-SPC) bonding system was developed by incorporating Cu particles as reinforcing fillers. To evaluate the effect of Cu particle incorporation on the mechanical bonding performance of LH-SPC joints, two types of SPCs were prepared: a conventional LH-SPC without Cu particles and a Cu-LH-SPC containing 3 vol% Cu particles. The mechanical bonding properties of the resulting joints were assessed and compared using ball shear and microhardness tests. The results demonstrated that both LH-SPC systems produced solder balls with uniform and suitable morphologies through effective conduction-path formation by the molten solder fillers, irrespective of the presence of Cu particles. Moreover, the Cu-LH-SPC joints exhibited superior mechanical bonding performance compared with the conventional LH-SPC joints. This improvement was attributed to the combined strengthening effect of the LMS/HMS fillers and the reinforcing action of the uniformly distributed Cu particles within the joint.

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Since the properties of electrogalvanized steel sheets depend on the crystal orientation of the deposited Zn, the effects of current density and substrate characteristics on the orientation relationship between Zn and Fe were investigated. Chemically polished Al-killed steel sheets, IF steel sheets, and high-purity electrolytic Fe were used as substrates. The crystal orientation relationships between Zn and Fe were analyzed by electron backscatter diffraction. On Al-killed steel sheets, Zn grew epitaxially at 1500 to 9000 A·m⁻² according to the Burgers orientation relationship, {101}Fe // {0001}Zn. In contrast, at 15000 A·m⁻², the orientation relationship {111}Fe // {0001}Zn was observed. On IF steel sheets, Zn was predominantly oriented with its {0001} planes over the entire current density range, and the orientation relationship {111}Fe // {0001}Zn was maintained. On high-purity electrolytic Fe, the orientation relationship {111}Fe // {0001}Zn was observed at 1500 A·m⁻², whereas it changed to {101}Fe // {0001}Zn at 15000 A·m⁻². These results indicate that the Zn/Fe orientation relationship and the crystal orientation of Zn are determined by the competition between epitaxial growth and electrodeposition overpotential, and that the manifestation of these effects depends on the grain size of the substrate.

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Heusler alloys (X₂YZ) are a group of ternary intermetallic compounds. From various possible sets of X, Y, and Z, we previously discovered the Co₂FeGe catalyst with excellent selectivity for selective hydrogenation of alkynes. To obtain further insights into the reaction mechanism, in this study, we compared the catalytic activity of different surfaces using epitaxial thin films and conducted deuteration of C₂H₄. The catalytic tests indicated that the (110) surface mainly provides the active sites; the deuteration experiment showed that alkene molecules can adsorb on Co₂FeGe, suggesting that the high alkene selectivity is probably due to a high energy barrier for further hydrogenation to alkanes.

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TSV technology is a key enabler for high-density 3D semiconductor packaging, providing high-density vertical interconnections between different layers and chips by filling deep and narrow vias with conductive materials such as copper. The quality of TSV filling directly affects the electrical performance and reliability of the packaging, and achieving a stable and uniform filling process remains a critical challenge in 3D packaging technologies. In this study, we successfully achieved void-free filling of through-silicon vias (TSVs) with an aspect ratio of 1:5 (5 μm in diameter and 25 μm in depth) through a copper electroplating process using thioflavin T and gelatin as organic additives. In addition, we investigated the relationship between the cross-sectional images of the filled TSV and the electrochemical behavior of the additives using a Linear Sweep Voltammetry (LSV) technique.

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To promote the recycling of lithium-ion batteries, it is essential to develop pretreatment technologies that can efficiently delaminate and recover electrode layers containing active materials. In this study, we investigated the applicability of an underwater ultrasonic delamination technique, proposed by the authors, to used cells and commercial batteries. Ni–Co–Mn (NCM) ternary oxide cathodes were used to compare delamination behavior before and after charge/discharge cycles. After cycling, delamination was facilitated by the formation of aluminum fluoride (AlF3) at the interface between the aluminum (Al) current collector and the cathode material. Furthermore, underwater ultrasonic treatment was applied to cathodes from four types of commercial cylindrical cells. While some electrodes were difficult to delaminate by ultrasonic treatment alone, delamination rates exceeding 95% were achieved when combined with a preheating step at 200–400 °C. Analysis of the polyvinylidene fluoride (PVdF) binder content and cutting strength of the cathode material revealed that preheating reduced binder adhesion strength. Under these conditions, cavitation impacts generated during ultrasonic treatment effectively acted on both the internal structure of the cathode material and the cathode material/Al foil interface, thereby promoting separation and delamination. Overall, these results demonstrate that underwater ultrasonic treatment, when combined with appropriate pretreatment conditions, can be applied to various commercial spent electrodes with different structures, materials, and degradation states. The technique is expected to offer high adaptability in actual recycling processes, contributing to the expansion of applicability and improved efficiency of the overall recycling workflow.

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The effects of Cl⁻, gelatin and Sb(III) additions on the current efficiency and crystal morphology of Zn electrodeposition from the electrowinning solutions were investigated. When Cl⁻ (300 mg/L), gelatin (1 mg/L) and Sb (5 μg/L) were added individually, the current efficiency increased by 1–1.5% compared with the additive-free case. When two of these additives were used in combination, the current efficiency also increased compared with the additive-free condition, with the largest improvement observed for the combination of Cl⁻ and gelatin. This is attributed to the complementary effects of Cl⁻, which promotes Zn deposition, and gelatin, which suppresses hydrogen evolution. When Cl⁻ coexisted with either gelatin or Sb, the grain size of the deposited Zn became larger than in the cases where gelatin or Sb was added alone. Since the addition of Cl⁻ reduces the overpotential for Zn deposition, it is considered that the nucleation rate decreases, leading to an increase in grain size. The number of bubble marks on the deposited Zn increased with the addition of Cl⁻, but decreased when gelatin or Sb was present together with Cl⁻. These results suggest that an increase in the nucleation rate of Zn reduces the formation of bubble marks.

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Li₁₀GeP₂S₁₂ solid electrolytes, which exhibit ionic conductivity comparable to that of organic electrolytes, have attracted attention. An excess sulfur solution method for short-time synthesis of Li₁₀GeP₂S₁₂ has been proposed, and it has been revealed that the heat treatment process using a titanium boat improves ionic conductivity compared to other combustion boats, such as quartz boats. To elucidate the mechanism, analysis including X-ray diffraction and Raman spectroscopy were conducted, and they revealed the formation of lattice distortion related to the enhanced ionic conductivity. Furthermore, applying a Ge-rich composition precursor successfully achieved the liquid-phase synthesis of Li₁₀GeP₂S₁₂ solid electrolyte with high ionic conductivity.

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The effect of silver overlayer thickness on the power-generation and cooling characteristics of bismuth telluride-based thermoelectric modules containing a nickel-phosphorus interlayer was investigated. An electroless nickel-phosphorus layer was formed on n-type and p-type thermoelectric elements, followed by silver electrodeposition with thicknesses of 1, 2 and 6 μm. Cross-sectional scanning electron microscopy confirmed the formation of a multilayer metallization structure consisting of a nickel-phosphorus interlayer and an outer silver layer on the bismuth telluride substrate. Under a temperature difference of 100 K, the module containing a 6 μm-thick silver layer exhibited the highest measured output power among the investigated specimens. In cooling operation, silver-coated modules showed markedly lower cold-side temperatures than the uncoated and nickel-phosphorus-coated modules. In particular, the 6 μm-thick silver layer was advantageous under high-current operation, whereas the 2 μm-thick layer showed favorable steady-state cooling behavior at 3 A. These results demonstrate that controlling silver thickness on a nickel-phosphorus interlayer is important for tailoring the electrical and thermal responses of bismuth telluride-based thermoelectric modules.

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This study investigates microstructural evolution during powder-bed fusion by comparing a conventional two-particle model with a powder-bed model of titanium nanoparticles under low- and high-speed thermal cycles using molecular-dynamics simulations. The comparison reveals that both models exhibit similar surface-melting behavior under low-speed thermal cycling conditions. However, a distinct discrepancy emerges under high-speed conditions. In the two-particle model, surface relaxation is limited by the viscous relaxation time, enabling nanoscale surface irregularities to persist above the melting point. Crucially, the powder-bed model captures a unique structural instability, in which the retained surface irregularities initiate a pronounced loss of symmetry during molten-region expansion. Sensitivity analyses involving subtle spatial shifts of the heating region reveal that this asymmetry is highly sensitive to local boundary conditions, indicating that minute geometric fluctuations in the initial powder arrangement can be amplified into a macroscopic localized morphology through a surface-tension-driven mechanism. Furthermore, the virial stress analysis indicates that this asymmetric melt expansion generates lateral tensile stresses on adjacent unmolten particles. These stresses promote twinning deformation and subsequently induce anisotropic crystallization owing to the Poisson effect. These findings successfully clarify the fundamental limitations of simplified two particle approximations and highlight the critical role of the collective powder topology in determining the melting-front dynamics and localized defect formation in high-rate metal additive manufacturing.

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The time-dependent variation of effects of thiourea addition on Cu electrodeposition, and the electrochemical oxidation behavior of thiourea, were investigated by impedance measurements and cyclic voltammetry. In an aqueous sulfuric acid solution containing thiourea, an oxidation current of thiourea was observed at approximately 0.15–0.20 V on a Cu electrode and at approximately 0.7 V on a Pt electrode. The addition of thiourea or formamidine disulfide (FDS) decreased the charge transfer resistance of Cu deposition, thereby promoting Cu deposition. The FDS-added solution exhibited a lower charge transfer resistance than the thiourea-added solution. In the thiourea-containing solution, the charge transfer resistance further decreased with time from initial stage. Thereafter, it increased, and the additive effect gradually diminished. In the FDS-containing solution, the charge transfer resistance increased with time from the initial stage, and the additive effect gradually diminished. The loss of the additive effect occurred more rapidly under electrolysis conditions. This may be due to the acceleration of FDS decomposition induced by electrolysis. The enhancing effect of thiourea at initial stage is attributed to its conversion into FDS via electrochemical or chemical oxidation, which promotes the deposition reaction via a Cu[FDS]⁺ complex. In contrast, FDS may undergo hydrolysis, ultimately leading to the loss of its additive effect.

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In this study, the ballistic limit velocity and energy absorption of four composite laminates (B3-16, H3-16, H3B3, and H3K3 with various stacking sequences were compared under high-velocity impacts using numerical simulations. The results obtained from the user-defined subroutine (VUMAT) validated the reliability of the model. The analysis revealed new insights into three-dimensional and two-dimensional damage patterns, including delamination, fiber and matrix failures, and back-face deformation behavior. Damage started at the contact surfaces and propagated until the final ply failure, with significant energy absorption attributed to backside deformation of the laminate. The front face of the spherical impactor flattened and mushroomed post-impact. We employed the Yen criteria to model intralaminar failure and utilize cohesive interactions between plies to elucidate progressive interlaminar damage. Notably, the B3-16 laminate exhibited higher ballistic velocity and energy absorption than H3-16, H3B3, and H3K3. Overall, basalt fiber hybridization offers advantages, such as cost savings, enhanced radiation resistance, increased compression strength, and recyclability, since basalt fibers are considerably less expensive than Kevlar fibers.

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Multi-phase lightweight AlTiCrV_0.5Fe_0.5 high-entropy alloy (HEA) fabricated by spark plasma sintering (SPS) was heat-treated at 750, 900, and 1050 °C to control its microstructure and wear performance. The microstructures consisted of a C14 Laves-phase matrix containing fine BCC1 precipitates, along with locally distributed Ti-rich BCC2 regions and Cr-rich σ segregation regions, all of which evolved as a function of heat-treatment temperature. The average coefficient of friction (COF) was lowest at 900 °C (0.13), whereas the specific wear rate was lowest at 750 °C (20 × 10⁻⁵ mm³/N·m). This phenomenon arises because the COF reflects contact stability during sliding, whereas wear loss is more strongly influenced by subsurface damage and delamination. Wear-track and wear-debris analyses revealed predominantly abrasive wear with limited delamination at 750 °C, while increased oxidative wear and delamination in the as-sintered and 1050 °C led to greater friction fluctuations and wear loss. Overall, these results demonstrate that heat-treatment-induced microstructural evolution can optimize friction stability and wear resistance without compositional modification.

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In this study, an Al_0.75VCrZrNb refractory high-entropy alloy was prepared via mechanical alloying, spark plasma sintering, and subsequent heat treatment. The oxidation behavior was investigated at 900 °C. Differences in mutual solubility led to the formation of multiple phases. Zr, which has low solubility with the other elements, precipitated and oxidized. After oxidation, oxides with high thermodynamic driving forces formed selectively in each microstructure, followed by the formation of complex oxides. Consequently, surface and internal cracks formed due to differences in thermal expansion coefficients between oxides and stresses induced by oxide formation. Surface oxidation and internal diffusion occurred simultaneously due to crack formation, exhibiting a power-law exponent of 1.23 and an oxidation rate of 9.86 × 10^-1 mg/cm²·h during the initial oxidation stage. In the later stage, the oxidation rate markedly decreased, with a power-law exponent of 4.73 and an oxidation rate of 2.27 × 10^-1 mg⁴/cm⁸·h. This study indicates that the multi-phase governs selective oxidation and complex oxide formation, which critically influence crack development and oxidation degradation in refractory high-entropy alloys.

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The effect of nitrogen doping in tantalum capacitors was investigated. Numerous studies have shown that nitrogen doping of tantalum improves the leakage current by suppressing the interdiffusion of tantalum and oxygen atom at the tantalum/tantalum-pentoxide interface. However, these findings were previously demonstrated only indirectly by electrical performance. In this paper, direct observation of interdiffusion was carried out using Scanning Electron Microscopy and Transmission Electron Microscopy, Fast Fourie Transformation, and line analysis with leakage current evaluation by wet electrical test. The results confirmed that nitrogen-doped samples exhibited higher resistance to interdiffusion with an applied heat treatment. Nitrogen doping provides lower leakage current on capacitors at room temperature and after heat treatment.

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While selective laser melting (SLM) is useful for fabricating Ti-6Al-4V ELI implants with complex geometries, the rapid and repeated melting–solidification cycles produce pores, unmelted powders, and martensitic microstructures, which strongly affect mechanical response. In this study, Ti-6Al-4V ELI (Grade 23, UNS R56401) specimens were fabricated along two orientations via SLM at scan speeds of 625, 520, 450, 390, and 350 mm/s. Their microstructural evolution was examined through optical microscopy and field-emission scanning electron microscopy, while their hardness and compressive properties were evaluated by micro-Vickers indentation and compression testing. The pore fraction varied non-monotonically with the scan speed. Lack-of-fusion type defects and unmelted powders were noted at relatively high scan speeds, whereas irregular molten boundaries were observed at excessively low scan speed. The lowest pore fraction was obtained near 390 mm/s, where the melt-pool stability was improved. The corresponding microstructure mainly comprised α–matrix and acicular α′–martensite while the hardness varied with both the pore fraction and martensitic morphology. Compression testing showed that the mechanical response was affected by not only the scan speed but also the building orientation. The vertically built specimens generally exhibited higher fracture absorption energies than the horizontally built specimens, which indicates that the loading direction relative to the building orientation is important for compressive reliability. Based on these results, the SLM processing window for Ti-6Al-4V ELI should be determined by considering pore formation, martensitic microstructure, and orientation-dependent compressive behavior simultaneously.

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Ultra-lightweight high-entropy alloys (HEAs) based on the FeMnAlTiSiMg system were fabricated via powder metallurgy to clarify the effects of magnesium addition on phase stability and specific strength. Elemental powders were mechanically alloyed and consolidated through spark plasma sintering, with the magnesium content varied from 0 to 1.0 molar ratio. Phase constitution and microstructural evolution were examined using X-ray diffraction and electron microscopy, while density and mechanical properties were assessed through compression testing. Alloys containing up to 0.5 mol of magnesium were found to predominantly exhibit body-centered cubic (BCC) or BCC/B2 solid-solution phases, whereas higher magnesium contents demonstrated phase separation accompanied by secondary phase formation. The alloy density decreased monotonically with increasing magnesium content, reaching values below 5.0 g/cm³. Among the compositions investigated, FeMnAlTiSiMg_0.25 displayed the highest compressive yield strength and specific yield strength. Further magnesium addition resulted in reduced strength and ductility. These results demonstrate that controlled magnesium addition combined with powder-metallurgy processing constitutes an effective approach for developing FeMnAlTiSiMg_x ultra-lightweight HEAs with a balanced combination of phase stability and specific strength.

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Single-phase lightweight high-entropy alloys (HEAs) often provide limited tunability of macroscopic properties. This study aimed to induce multi-phase formation in AlTiVCr-based lightweight HEAs by controlling the mixing enthalpy via elemental additions, as well as correlate the resulting phase evolution with the compressive properties. The HEAs were fabricated through high-energy ball milling, followed by spark plasma sintering. All compositions exhibited body-centered cubic and Laves phases with minor residuals, suggested by CALPHAD-assisted thermodynamic screening. Especially, AlTiV_0.5CrFe_0.5, which exhibited the fewest intermetallic compounds and a tendency toward a homogeneously mixed main phase, displayed the highest compressive fracture strength (1,994 MPa). Conversely, AlTiV_0.5CrSn_0.5, which exhibited a relatively strong tendency toward phase separation and intermetallic compound formation, demonstrated a low compressive fracture strength (1,528 MPa). Compared with representative HEAs reported in the literature, the enhanced compressive strengths of the AlTiVCr-based HEAs indicate that the formation of multi-phase improved their compressive properties. These findings suggest that mixing enthalpy-guided design, coupled with CALPHAD screening and powder metallurgy, can be leveraged to engineer multi-phase lightweight HEAs with tunable properties for lightweight structural applications.

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Colored coatings produced by electrodeposition can significantly enhance the value of materials. The polarization curves for composite deposition from a Zn–Ni plating solution were measured, and the deposition potential region in which color appeared was investigated. In addition, the structure of the colored deposited films was analyzed by transmission electron microscopy. Colored deposited films were obtained at potentials close to the equilibrium potential for Zn deposition. TEM observations and EDX analysis revealed that the colored films consisted of a composite structure with ZnO and ZnS as the matrix phases, in which fine metallic Ni nanoparticles with diameters of 3–5 nm were uniformly dispersed.

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Rotary aluminum sputtering targets require durable inner surfaces to withstand long-term exposure to flowing coolant, which can induce corrosion, wear, and thermal degradation. In this study, the effect of inner-surface treatment on the durability of cylindrical aluminum sputtering targets was systematically investigated by comparing untreated aluminum, chromium-plated aluminum, and anodized aluminum surfaces with different oxide thicknesses. Chromium plating increased surface hardness and improved wear resistance compared to untreated aluminum; however, interfacial delamination and a noticeable reduction in thermal conductivity were observed. Anodized aluminum surfaces exhibited enhanced corrosion resistance without forming discrete interfacial layers, while the Anodized Al–Thin condition showed a marked increase in surface hardness. While excessively thick anodic oxide layers showed brittle wear behavior, the Anodized Al–Thin condition provided stable friction behavior, low wear volume, and minimal thermal penalty. Thin film deposition experiments confirmed that inner-surface anodizing does not adversely affect aluminum film thickness or electrical resistivity after annealing. These results suggest that anodized aluminum with a controlled oxide thickness offers a promising inner-surface protection strategy for rotary sputtering targets, providing improved corrosion and wear resistance without compromising thermal management or thin film performance.

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The energetic performance of micrometer-sized aluminum powder is intrinsically limited by its native amorphous Al₂O₃ layer, which acts as a diffusion barrier and prevents a sufficient fraction of the aluminum core from participating in oxidation. In this study, the native oxide layer of aluminum powder (average particle size ≈ 7 μm) was removed using an aqueous hydrofluoric acid solution, and a thiol-based self-assembled monolayer (SAM) was subsequently formed on the activated surface using two thiol compounds of different alkyl-chain lengths, 1-octadecanethiol (ODT) and 1-dodecanethiol (DDT). The formation and chemical characteristics of the SAM were confirmed by FT-IR and XPS, and the thermal oxidation and heat-release behavior were evaluated by TGA–DSC under an air atmosphere. The effect of SAM formation and alkyl-chain length on the exothermic behavior of the powder is discussed in terms of pre-heating surface protection and high-temperature oxidation enhancement.

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Electrodeposition of Zn–V composite films was performed from non-suspension solutions containing VO²⁺ ions, and the effects of electrolytic factors such as current density, additive, solution temperature and agitation on the codeposition behavior of V compounds and the microstructure of the deposited films were investigated. The critical current density for Zn deposition from a Zn-V solution decreased with decreasing solution temperature and without agitation. The addition of polyethylene glycol (PEG) slightly decreased the current efficiency of Zn, and slightly increased the V content in the deposited films. The curve showing the relationship between current density and current efficiency of Zn shifted toward lower current densities with decreasing temperature, whereas it shifted toward higher current densities with agitation. The curve showing the relationship between current density and V content in the deposited films shifted toward lower current densities with decreasing temperature and toward higher current densities with agitation. V compounds were uniformly codeposited in the deposited films with decreasing solution temperature and the addition of PEG. A decrease in solution temperature and the addition of PEG increased the overpotential for deposition, resulting in smaller Zn platelet crystals. V compounds are co-deposited in the gaps between Zn platelet crystals, and it is thought that as the size of the platelet crystals decreases, the gaps between the crystals become smaller and their number increases, leading to the co-deposition of V compounds being dispersed. Furthermore, in electrolysis from a solution containing PEG, the number of hydrogen generation sites increases, which is expected to increase the number of hydrolysis sites for VO²⁺, and is thought to be the factors of the uniform co-deposition of V compounds.

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Both high strength and high ductility were achieved by bimodal microstructure fabricated in near-α titanium alloy Ti-1100 through heat treatment alone without working. The initial microstructure was either α or α′ martensite lamellae. By holding for a short time above the β transus followed by air cooling or quenching, coarse lamellar matrix (α or tempered martensite) with interlamellar fine α or α′ martensite was obtained, resulting in an α-based bimodal microstructure. The high strength was largely imparted by the fine grains, while the high ductility was provided by the coarse lamellae. The high ductility despite the high strength was attributed to the increased strain hardening rate derived from the bimodal microstructure.

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The hot shortness caused by Cu and Sn contained in steel scrap represents a significant technical challenge for promoting carbon neutrality in the steel industry. Hot shortness induced by Cu is considered to occur when liquid Cu, formed at the oxide scale/substrate interface during steel oxidation, penetrates the grain boundaries; however, the detailed mechanism of this penetration remains unclear. In this study, Fe–0.08C–0.3Si–2Mn–0.3Cu–0.01Sn–0.04Ni–0.2Cr steel was heat-treated under conditions that induce hot shortness, and the Cu concentration distribution at the grain boundaries of the substrate was analyzed in detail using Electron Probe Micro Analyzer (EPMA), Scanning Electron Microscope (SEM) equipped with Energy Dispersive X-ray Spectroscopy (EDS), and Transmission Electron Microscope (TEM) equipped with EDS. Furthermore, molecular dynamics simulations were performed to evaluate the penetration behavior when liquid Cu contacts random grain boundaries of Fe. The results revealed that, in the early stage, Cu does not penetrate the grain boundaries as a liquid phase but diffuses along the grain boundaries in the solid phase beyond its solubility limit. After this solid-state grain boundary diffusion of Cu, it is inferred that liquid Cu subsequently forms or infiltrates along the grain boundaries. These findings suggest that controlling the grain boundary diffusion of Cu is essential for mitigating hot shortness.

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High-entropy alloys (HEAs) are promising for advanced structural applications because they can achieve a unique combination of strength, damage tolerance, and environmental resistance. In powder-metallurgy processing routes, mechanical alloying (MA) may introduce carbon contamination, which significantly influences phase evolution and microstructural development. Carbon uptake, phase evolution, and mechanical response in a CoCrFeNiTi HEAs processed by mechanical alloying followed by spark plasma sintering were found to be strongly dependent on MA time. The carbon content in milled powders was quantified by combustion analysis. Phase constitution and lattice parameters were analyzed using X-ray diffraction (XRD), with lattice constants determined by Nelson–Riley extrapolation and crystallite size and lattice strain evaluated by Williamson–Hall analysis. Dislocation density was estimated using a Burgers-vector-based formulation. The sintered compacts were characterized by XRD, scanning electron microscopy with energy-dispersive spectroscopy (SEM–EDS), electron probe microanalysis (EPMA), and electron backscatter diffraction (EBSD). Mechanical properties were evaluated using micro-Vickers hardness and nanoindentation, from which the performance indices H/E and H³/E² were derived. Carbon uptake increased monotonically with MA time and tended to saturate at longer milling durations. The milled powders formed a predominantly BCC solid solution after MA, accompanied by crystallite refinement and increased lattice strain/dislocation density. After SPS, the microstructure evolved into an FCC-dominant matrix with TiC-related regions and Cr-rich phases. Grain refinement and increased Geometrically Necessary Dislocations (GND) were observed with longer MA time. Mechanical properties showed a hardness drop at short MA time followed by recovery and stabilization at longer MA time, while nanoindentation-based performance indices suggested an optimal intermediate MA-time window. These results demonstrate that MA time controls not only alloying/defect states but also carbon-mediated precipitation and phase balance, providing a practical guideline for optimizing MA–SPS processing of Ti-containing HEAs.

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Announcement Concerning Article Retraction
The following paper has been withdrawn from the database of Mater. Trans., because a description based on a misinterpretation of the experimental results was found by the authors in advance of publication after acceptance.
Mater.Trans. 52(2011) Advance view.
Improvement in Fatigue Strength of Biomedical β-Type Ti-Nb-Ta-Zr Alloy while Maintaining Low Young’s Modulus through Optimizing ω-Phase Precipitation

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