Metals

12 pages, 970 KB

Open AccessArticle

Influence of Ga Content and Pre-Treatment on the Mechanical Properties of High-Mg-Content Al-Mg-Zn-Ga Alloys

by Boyu Xue, Qilong Liu, Wei Xiao, Xiwu Li, Guanjun Gao, Hongwei Yan, Kai Wen, Xiaowu Li, Yongan Zhang, Ligen Wang and Baiqing Xiong

Metals 2026, 16(2), 196; https://doi.org/10.3390/met16020196 - 6 Feb 2026

Abstract

Al-Mg-Zn crossover alloys are promising lightweight structural materials. This study systematically investigates the effects of Ga content (0–0.8 wt.%) and pre-treated aging (PA) on the mechanical properties and microstructure in high-Mg-content Al-Mg-Zn crossover alloys. The results show that, under two-step aging (90 °C/24 [...] Read more.

Al-Mg-Zn crossover alloys are promising lightweight structural materials. This study systematically investigates the effects of Ga content (0–0.8 wt.%) and pre-treated aging (PA) on the mechanical properties and microstructure in high-Mg-content Al-Mg-Zn crossover alloys. The results show that, under two-step aging (90 °C/24 h + 140 °C/24 h), increasing the Ga content from 0 to 0.8 wt.% leads to a significant enhancement in mechanical strength. The hardness, ultimate tensile strength (UTS) and yield strength (YS) increased from 102.8 HV to 169.2 HV, from 457.7 MPa to 592.0 MPa, and from 288.0 MPa to 505.7 MPa, respectively, while maintaining an elongation (EL) of 15.8%. This enhancement is attributed to increased Ga content, which promotes precipitation refinement and a morphology transition from rod-like to fine spherical precipitates. Furthermore, in the alloy containing 0.4 wt.% Ga, the application of PA treatment enhanced the UTS and YS from 527.3 MPa to 569.3 MPa, and from 413.7 MPa to 483.7 MPa, respectively. This work demonstrates that the appropriate addition of Ga and PA treatment effectively enhances the precipitation behavior and tensile properties of Al-Mg-Zn alloys, providing valuable guidance for the development of high-performance, lightweight structural materials. Full article

(This article belongs to the Section Metal Casting, Forming and Heat Treatment)

22 pages, 4964 KB

Open AccessArticle

Microstructure and Toughness of CGHAZ in Low-Carbon Nb-Ti-La Steel Under High Heat Input Welding Thermal Cycles

by Qiuming Wang, Shibiao Wang, Qingfeng Wang and Riping Liu

Metals 2026, 16(2), 195; https://doi.org/10.3390/met16020195 - 6 Feb 2026

Abstract

This study employed a Gleeble-3800TM thermal simulator to conduct thermal cycle experiments on the coarse-grained heat-affected zone (CGHAZ) of Nb-Ti-La microalloyed steel under welding heat inputs of 50, 80, 100, and 120 kJ/cm. A systematic analysis was carried out to investigate the influence [...] Read more.

This study employed a Gleeble-3800TM thermal simulator to conduct thermal cycle experiments on the coarse-grained heat-affected zone (CGHAZ) of Nb-Ti-La microalloyed steel under welding heat inputs of 50, 80, 100, and 120 kJ/cm. A systematic analysis was carried out to investigate the influence of heat input on the microstructure and impact toughness of the CGHAZ. The results indicate that the microstructure of the CGHAZ across different heat inputs consists of acicular ferrite (AF), granular bainite ferrite (GBF), polygonal ferrite (PF), as well as hard phases such as M/A constituents and degenerated pearlite (DP). With increasing heat input, the content of GBF decreases monotonically, while the content of PF increases monotonically, and the amount of hard phases rises continuously. In contrast, the content of AF initially increases and then decreases, reaching its peak at 100 kJ/cm. The microstructural changes induced by higher heat input lead to increased inhomogeneity in the local microstrain, thereby causing a monotonic reduction in crack initiation energy. Regarding crack propagation energy, the optimal performance is achieved at 100 kJ/cm due to the formation of a high proportion of AF, which heterogeneously nucleates on La-rich inclusions. This structure provides a high density of high-angle grain boundaries that effectively hinder crack propagation. Consequently, under the combined influence of crack initiation and propagation behaviors, the CGHAZ exhibits the best impact toughness at a heat input of 100 kJ/cm. Full article

(This article belongs to the Special Issue Recent Advances in High-Performance Steel (2nd Edition))

13 pages, 2022 KB

Open AccessArticle

The Parametrization of Thermoelastic Martensite Phase Transformations at Constant Stress in Shape Memory Alloys Using a Sigmoidal Boltzmann Function

by Maxim A. Orlov, Matvey G. Fedin, Vladimir S. Kalashnikov, Victor V. Koledov, Kirill D. Aksenov, Anton V. Nesolenov, Gulbarshin K. Shambilova, Georgy I. Makarov and Ivan S. Levin

Metals 2026, 16(2), 194; https://doi.org/10.3390/met16020194 - 6 Feb 2026

Abstract

The parametrization of the thermomechanical behavior of shape memory alloys (SMAs) under constant load is described in terms of their functional properties. The deformation–temperature–stress behavior of SMAs from various alloy systems—such as Ni-Ti, Ni-Ti-Cu, and Ni-Mn-Ga—was parametrized using a sigmoidal function. This approach [...] Read more.

The parametrization of the thermomechanical behavior of shape memory alloys (SMAs) under constant load is described in terms of their functional properties. The deformation–temperature–stress behavior of SMAs from various alloy systems—such as Ni-Ti, Ni-Ti-Cu, and Ni-Mn-Ga—was parametrized using a sigmoidal function. This approach enables the characterization of phase transformation parameters, including transformation temperatures, kinetic parameters, and the relationship between recoverable deformation and applied stress. It is shown that the sigmoid function can serve as a universal descriptor of thermoelastic phase transformations across different alloy systems and transformation types, such as B2–R–B19′–R–B2 (Ni-Ti-Cu), B2–R–B19′–B2 (Ni-Ti), and B2 (L2₁)–B19′ (L2₀)–B2 (L2₁). A correlation coefficient of approximately 0.99 was achieved. The present work extends the theoretical framework of diffuse martensitic transitions in SMAs, for which the sigmoid function has been theoretically derived to describe phase fractions. The article’s novelty lies in shifting from pure mathematical approximation (curve fitting) to physical parametrization of SMA behavior specifically under constant stress (actuator mode). Full article

(This article belongs to the Special Issue Advances in Shape Memory Alloys: Theory, Experiment and Calculation)

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20 pages, 6521 KB

Open AccessArticle

Ductility Control in Laser Powder Bed Fusion (LPBF) AlSi10Mg via Silicon Precipitation and Coarsening During Heat Treatment

by Ning Zhang, Yao Wang, Chuanhui Huang, Bin Yang, Yan Chen and Jinguo Ge

Metals 2026, 16(2), 193; https://doi.org/10.3390/met16020193 - 6 Feb 2026

Abstract

Laser powder bed fusion (LPBF) was adopted to manufacture AlSi10Mg, and two post-processing schedules, T4 (510 °C/2 h + water quench) and T6 (T4 + 180 °C/6 h), were applied to elucidate how Si precipitation size controls ductility. The as-built alloy consisted of [...] Read more.

Laser powder bed fusion (LPBF) was adopted to manufacture AlSi10Mg, and two post-processing schedules, T4 (510 °C/2 h + water quench) and T6 (T4 + 180 °C/6 h), were applied to elucidate how Si precipitation size controls ductility. The as-built alloy consisted of an α-Al matrix with a grid-like eutectic Si network and achieved UTS > 480 MPa but exhibited build-direction-dependent tensile anisotropy. Heat treatment promoted Si precipitation from the supersaturated α-Al matrix and transformed the eutectic network via fragmentation, spheroidization, and Ostwald ripening, leading to pronounced softening and improved elongation. After T4, the yield strength and UTS decreased by >50%, while elongation increased from 10.9% to 22.27%; T6 provided a slight strength recovery accompanied by a marginal ductility reduction. Mechanistically, a high number density of fine Si precipitates enhances dislocation storage and delays damage accumulation, whereas coarse, non-shearable Si particles intensify local strain gradients, facilitate void nucleation at the matrix/particle interface, and accelerate fracture. Overall, tailoring Si precipitation/coarsening offers an effective route to improve ductility and mitigate anisotropy in LPBF AlSi10Mg. Full article

(This article belongs to the Special Issue Advances in 3D Printing Technologies of Metals—3rd Edition)

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22 pages, 40293 KB

Open AccessArticle

Maritime Applications as Motivation for Analytical Calculation of Thermal History in Low-Carbon Mild Steel WAAM Cylinders

by Eleftherios Lampros and Anna D. Zervaki

Metals 2026, 16(2), 192; https://doi.org/10.3390/met16020192 - 5 Feb 2026

Abstract

This study reviews the application of wire arc additive manufacturing (WAAM) technology in maritime engineering and investigates an experimentally driven analytical approach for prediction of thermal distributions based on the Rosenthal solution. Two ER70S-6 low-carbon steel WAAM cylinders were fabricated using gas metal [...] Read more.

This study reviews the application of wire arc additive manufacturing (WAAM) technology in maritime engineering and investigates an experimentally driven analytical approach for prediction of thermal distributions based on the Rosenthal solution. Two ER70S-6 low-carbon steel WAAM cylinders were fabricated using gas metal arc welding (GMAW) and plasma arc welding (PAW) processes, with interlayer temperatures of 453 °C and 250 °C, respectively. Accurately measuring the temperature field to tailor the microstructure has long been a challenge. The results indicated a significant deviation between the analytical predictions and the experimental data. To address this discrepancy, a hybrid approach combining analytical and experimental results was implemented. Time intervals between layers, extracted from the experimental data, were incorporated into the Rosenthal equation to improve the accuracy of temperature field predictions. The microstructure at the bottom, middle, and top regions of the WAAM components was examined using optical microscopy. Tensile testing and Vickers microhardness measurements were conducted to evaluate mechanical properties. Scanning electron microscopy (SEM) was used to analyze fracture surfaces and identify fracture modes. The results were consistent with those reported for other ER70S-6 cylindrical WAAM components. This work highlights limitations of the Rosenthal solution and emphasizes the need for thermal models in WAAM applications. Full article

(This article belongs to the Special Issue Advanced Additive Manufacturing of Metallic Materials)

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15 pages, 7646 KB

Open AccessArticle

A Study on the Influence of Nitrogen Content on the Structural Performance and Stress Corrosion Resistance of 700 MPa Ultra-High-Strength Steel Bars

by Xiaomin Zhao, Zhiyi Wang, Xuemin Wang, Xuedong Li, Xiaochen Zhang, Xuequn Cheng and Chao Liu

Metals 2026, 16(2), 191; https://doi.org/10.3390/met16020191 - 5 Feb 2026

Abstract

This study investigates the influence of vanadium–nitrogen (V-N) microalloying design on the microstructure and mechanical properties of 700 MPa grade ultra-high-strength steel bars. Through the control of the V/N ratio and cooling rate, a yield strength exceeding 700 MPa was achieved in a [...] Read more.

This study investigates the influence of vanadium–nitrogen (V-N) microalloying design on the microstructure and mechanical properties of 700 MPa grade ultra-high-strength steel bars. Through the control of the V/N ratio and cooling rate, a yield strength exceeding 700 MPa was achieved in a steel with a pearlite–ferrite matrix. Microstructural characterization via optical microscopy (OM) and scanning electron microscopy (SEM) revealed that a V/N ratio of approximately 1:10 combined with a rolling cooling rate of 1–3 °C/s resulted in the steel bar exhibiting a yield strength of 774.21 MPa and a tensile strength of 971.13 MPa. The primary microstructure of the steel consisted of ferrite and pearlite. The steel featured fine grains and favorable crystallographic orientations, which contributed to its high yield strength and good ductility. Transmission electron microscopy (TEM) analysis indicated that under hot-rolling conditions, vanadium precipitated predominantly as nano-scale V(C,N) particles. These precipitates were distributed in both the pearlite and ferrite phases, thereby enhancing the tensile and yield strength. Furthermore, the steel with an optimal nitrogen content (0.0166 wt.%) and the finest grain structure (average grain size ≈ 2.618 μm) showed the lowest stress corrosion cracking (SCC) susceptibility, characterized by an elongation loss rate (I_δ) of 12.51%, demonstrating excellent SCC resistance. Full article

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15 pages, 4387 KB

Open AccessArticle

Effects of PZT Reinforcement on the Properties of Fe-Based Composites Fabricated by Powder Metallurgy

by Yousef Alshammari, Jafarali Parol, Fei Yang and Leandro Bolzoni

Metals 2026, 16(2), 190; https://doi.org/10.3390/met16020190 - 5 Feb 2026

Abstract

Fe composites are highly valued for their unique mechanical and magnetic properties, making them essential in various industrial applications. This study represents the first reported attempt to combine PZT into an Fe matrix, aiming to develop novel Fe-PZT composites. The primary objective was [...] Read more.

Fe composites are highly valued for their unique mechanical and magnetic properties, making them essential in various industrial applications. This study represents the first reported attempt to combine PZT into an Fe matrix, aiming to develop novel Fe-PZT composites. The primary objective was to assess how the concentration of PZT influences the properties of these composites. The results show that increasing the PZT content in Fe-xPZT composites (where x = 1, 5, and 10 wt.%) reduces the relative sintered density. Microstructural analysis reveals that the composites with higher PZT levels contained numerous large, irregularly shaped pores due to a pronounced Kirkendall effect and limited densification. Furthermore, the evaporation of the volatile PbO compound was observed to affect the thermal stability of the PZT system, leading to reduced composite homogeneity. SEM analysis showed the formation of intermetallic compounds corresponding to Fe₂Ti, FeTi, and FeZr₂. Finally, an increase in PZT content tends to degrade the tensile and mechanical properties of the Fe-xPZT composites, though they still do not fail catastrophically. These preliminary findings prove the concept of the feasibility of producing Fe-PZT composites and set the basis for the optimization of their manufacturing process. This should eventually unlock the possibility of producing multifunctional materials. Full article

(This article belongs to the Special Issue Heat Treatment and Mechanical Behavior of Steels and Alloys)

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18 pages, 5351 KB

Open AccessArticle

Evolution of Microstructure, Mechanical Properties and Residual Stress Prediction of Al₂O₃ Ceramic/TC4 Alloy Diffusion Bonded Joint

by Yangfan Fu, Dalong Cong, Tao Hu, Guangjie Feng, Zhongsheng Li, Dajun Chen, Zaijun Yi, Guangyu Yu, Wei Cong, Yifeng Wang and Dean Deng

Metals 2026, 16(2), 189; https://doi.org/10.3390/met16020189 - 5 Feb 2026

Abstract

This study systematically investigates the microstructure evolution, mechanical properties, and residual stress distribution in diffusion-bonded joints between Al₂O₃ ceramic and TC4 alloy. Motivated by the need for reliable high-temperature joints in advanced applications, this work addresses the challenges posed by [...] Read more.

This study systematically investigates the microstructure evolution, mechanical properties, and residual stress distribution in diffusion-bonded joints between Al₂O₃ ceramic and TC4 alloy. Motivated by the need for reliable high-temperature joints in advanced applications, this work addresses the challenges posed by the materials’ physicochemical differences. Joints were fabricated at temperatures ranging from 800 °C to 950 °C under a pressure of 3 MPa for 2 h. Microstructural characterization revealed the formation of a multi-layered interfacial structure, dominated by a Ti₃Al reaction layer, whose thickness increased with bonding temperature. The highest shear strength of 54 MPa was achieved at 850 °C, representing a key quantitative outcome of this parameter optimization. Beyond this temperature, excessive growth of the brittle Ti₃Al layer and associated residual stresses led to strength degradation and interfacial cracking. A three-dimensional finite element model was developed to simulate residual stress distributions, highlighting significant tensile stresses within the Ti₃Al layer and compressive stresses in the Al₂O₃ near the interface. The model further identified critical tensile stress concentrations along the vertical edges of the ceramic, which contribute to failure during shear testing. Full article

(This article belongs to the Section Welding and Joining)

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15 pages, 5144 KB

Open AccessArticle

Simulation on the Influence of Inclusion–Matrix Interaction on Crack Initiation and Growth in Hypo-Peritectic Steel

by Yanan Zeng, Xiangkan Miao, Junguo Li, Yukang Yuan, Bingbing Ge, Yitong Wang and Yajun Wang

Metals 2026, 16(2), 188; https://doi.org/10.3390/met16020188 - 5 Feb 2026

Abstract

Hypo-peritectic steels are susceptible to interfacial cracking during thin-slab continuous casting, in which non-metallic inclusions play a critical role. This study systematically investigates the effects of inclusion type and morphology on interface cracking behavior in the steel matrix, with the aim of improving [...] Read more.

Hypo-peritectic steels are susceptible to interfacial cracking during thin-slab continuous casting, in which non-metallic inclusions play a critical role. This study systematically investigates the effects of inclusion type and morphology on interface cracking behavior in the steel matrix, with the aim of improving billet shell quality. Hot tensile experiments were conducted using a Gleeble 3800 thermal simulator, and a finite element–based cohesive zone model was developed to simulate inclusion-induced crack nucleation and propagation. The results demonstrate that inclusions markedly influence interfacial stress distribution and damage evolution. The maximum interfacial stresses associated with MnS, Al₂O₃, and composite inclusions are 20.7, 23.4, and 30.5 MPa, respectively. Owing to severe stress concentration at sharp corners, composite inclusions exhibit the earliest crack nucleation at an applied stress of 11.3 MPa and the highest energy dissipation. In all cases, cracks initially nucleate at the location of maximum tensile stress (α = 90°), propagate along the interface, and subsequently penetrate into the matrix, ultimately leading to failure. The strong agreement between numerical simulations and experimental results confirms that angular inclusions accelerate damage by disrupting matrix continuity. These findings provide theoretical guidance for improving hypo-peritectic steel quality through inclusion morphology control during continuous casting. Full article

(This article belongs to the Special Issue Advances in Failure Analysis of Metallic Materials: Characterization and Modeling)

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25 pages, 10013 KB

Open AccessArticle

pH-Dependent Long-Term Degradation and Mechanical Integrity of LPBF-Fabricated Porous Ti-6Al-4V in Hank’s Solutions with Different pH Values

by Wei-Gang Lv, Zi-Meng Xiao, Ze-Xin Wang, Sheng Lu, Dubovyy Oleksandr and Liang-Yu Chen

Metals 2026, 16(2), 187; https://doi.org/10.3390/met16020187 - 4 Feb 2026

Abstract

Titanium alloys are widely used as bone graft materials due to their excellent corrosion resistance and biocompatibility. Implant failure can result from long-term exposure to body fluids and inflammation-induced pH decreases, both of which compromise the material’s corrosion resistance and mechanical stability. To [...] Read more.

Titanium alloys are widely used as bone graft materials due to their excellent corrosion resistance and biocompatibility. Implant failure can result from long-term exposure to body fluids and inflammation-induced pH decreases, both of which compromise the material’s corrosion resistance and mechanical stability. To address this issue, porous Ti-6Al-4V alloy was selected in this work. Immersion tests were conducted in Hank’s solution with different pH values (3, 5, and 7) for 90 days to simulate the in vivo microenvironment under various physiological conditions. The degradation behavior of porous Ti-6Al-4V alloy during the 90-day immersion period was systematically investigated using a combination of characterization techniques. The results indicated that TiO₂, Ca₃(PO₄)₂, and Ca(H₂PO₄)₂ phases were formed on the surface of the after 90 days of immersion. Massive dissolution of TiO₂ was observed in solutions with high H⁺ concentration (low pH). Ion release tests revealed that the concentration of titanium ions released was significantly higher in acidic solutions, suggesting that the passive film formed on porous Ti-6Al-4V alloy was unstable and prone to dissolution under acidic conditions. Consequently, a large amount of corrosion products accumulated on the specimen surfaces immersed in acidic solutions for a long duration. Moreover, the compression properties of the samples deteriorated after immersion. Specifically, the compressive strength decreased by 12.68 MPa, 11.67 MPa, and 5.84 MPa for sample immersed in solutions with pH = 3, 5, and 7, respectively. The significant reduction in compressive performance of the alloy in high H⁺ concentration solutions was attributed to the decreased compactness caused by ion release. The fracture mode of the porous Ti-6Al-4V alloy after immersion was identified as a mixed mode of ductile and brittle fracture. Full article

(This article belongs to the Special Issue Application of Biomedical Alloys)

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17 pages, 10354 KB

Open AccessArticle

Surface Nanocrystallization and Strengthening Mechanisms of SLM 316L Stainless Steel Induced by Shot Peening

by Hongfeng Luo and Yuxuan Wang

Metals 2026, 16(2), 186; https://doi.org/10.3390/met16020186 - 4 Feb 2026

Abstract

To address surface defects and enhance the wear resistance of 316L stainless steel parts fabricated by Selective Laser Melting (SLM), this study applied shot peening (SP) surface treatment to the SLM-processed samples. Ball-on-disk tribological tests were systematically conducted under water-lubricated conditions to investigate [...] Read more.

To address surface defects and enhance the wear resistance of 316L stainless steel parts fabricated by Selective Laser Melting (SLM), this study applied shot peening (SP) surface treatment to the SLM-processed samples. Ball-on-disk tribological tests were systematically conducted under water-lubricated conditions to investigate the evolution of surface morphology, microstructure, microhardness, and tribological performance before and after SP. The results indicate that SP induced severe plastic deformation in the surface layer, effectively refining the coarse columnar crystals and melt pool structures characteristic of SLM, and forming a crystalline hardened layer with a depth of 70–80 μm. Consequently, the surface microhardness increased by 21.97% compared to the un-peened samples. Under loads of 20 N and 30 N, the coefficient of friction (COF) of the SP-treated samples decreased by 16.36% and 12.4%, while the wear rate was reduced by 17.09% and 14.9%, respectively. In this load range, the samples primarily exhibited uniform plowing and localized adhesive wear, demonstrating significantly improved resistance to plastic deformation and crack initiation. However, when the load increased to 40 N, intense stress and thermal effects diminished the strengthening benefits of SP, resulting in no significant difference in tribological performance between the SP-treated and untreated samples. At this stage, the dominant wear mechanism transitioned to severe plastic deformation, extensive delamination, and thermally induced adhesion. Full article

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23 pages, 2375 KB

Open AccessArticle

Transformer-Based Dynamic Flame Image Analysis for Real-Time Carbon Content Prediction in BOF Steelmaking

by Hao Yang, Meixia Fu, Wei Li, Lei Sun, Qu Wang, Na Chen, Ronghui Zhang, Zhenqian Wang, Yifan Lu, Zhangchao Ma and Jianquan Wang

Metals 2026, 16(2), 185; https://doi.org/10.3390/met16020185 - 4 Feb 2026

Abstract

Accurately predicting molten steel carbon content plays a crucial role in improving productivity and energy efficiency during the Basic Oxygen Furnace (BOF) steelmaking process. However, current data-driven methods primarily focus on endpoint carbon content prediction, while lacking sufficient investigation into real-time curve forecasting [...] Read more.

Accurately predicting molten steel carbon content plays a crucial role in improving productivity and energy efficiency during the Basic Oxygen Furnace (BOF) steelmaking process. However, current data-driven methods primarily focus on endpoint carbon content prediction, while lacking sufficient investigation into real-time curve forecasting during the blowing process, which hinders real-time closed-loop BOF control. In this article, a novel Transformer-based framework is presented for real-time carbon content prediction. The contributions include three main aspects. First, the prediction paradigm is reconstructed by converting the regression task into a sequence classification task, which demonstrates superior robustness and accuracy compared to traditional regression methods. Second, the focus is shifted from traditional endpoint-only forecasting to long-term prediction by introducing a Transformer-based model for continuous, real-time prediction of carbon content. Last, spatial–temporal feature representation is enhanced by integrating an optical flow channel with the original RGB channels, and the resulting four-channel input tensor effectively captures the dynamic characteristics of the converter mouth flame. Experimental results on an independent test dataset demonstrate favorable performance of the proposed framework in predicting carbon content trajectories. The model achieves high accuracy, reaching 84% during the critical decarburization endpoint phase where carbon content decreases from 0.0829 to 0.0440, and delivers predictions with approximately 75% of errors within ±0.05. Such performance demonstrates the practical potential for supporting intelligent BOF steelmaking. Full article

(This article belongs to the Special Issue Advanced Simulation and Modeling Technologies of Metallurgical Processes—2nd Edition)

21 pages, 3012 KB

Open AccessArticle

Sustainable Production of Chromium–Manganese Ligatures from Low-Grade Iron–Manganese Ore and Ferrosilicochrome Dust: Thermodynamic Modeling and Experimental Verification

by Yerbolat Makhambetov, Sultan Kabylkanov, Saule Abdulina, Armat Zhakan, Azamat Burumbayev, Zhadiger Sadyk, Amankeldy Akhmetov and Alok Sarkar

Metals 2026, 16(2), 184; https://doi.org/10.3390/met16020184 - 4 Feb 2026

Abstract

This study investigates the thermodynamic and experimental aspects of producing a chromium–manganese ligature under high-temperature smelting conditions using low-grade iron–manganese ore and ferrosilicochrome (FeSiCr) dust as both a reducing agent and a chromium source. Thermodynamic modeling of the multicomponent Fe–Cr–Mn–Si–Al–Ca–Mg–O system was carried [...] Read more.

This study investigates the thermodynamic and experimental aspects of producing a chromium–manganese ligature under high-temperature smelting conditions using low-grade iron–manganese ore and ferrosilicochrome (FeSiCr) dust as both a reducing agent and a chromium source. Thermodynamic modeling of the multicomponent Fe–Cr–Mn–Si–Al–Ca–Mg–O system was carried out using the HSC Chemistry 10 and FactSage 8.4 software packages to substantiate the temperature regime, reducing agent consumption, and conditions for the formation of a stable metal–slag system. The calculations indicated that efficient reduction of manganese oxides and formation of the metallic phase are achieved at a smelting temperature of 1600 °C with a reducing agent consumption of approximately 50 kg. Experimental smelting trials conducted in a laboratory Tammann furnace under the calculated parameters confirmed the validity of the thermodynamic predictions and demonstrated the feasibility of obtaining a concentrated chromium–manganese ligature. The resulting metallic product exhibited a high total content of alloying elements and had the following chemical composition (wt.%): Fe 35.41, Cr 41.10, Mn 8.15, and Si 4.31. SEM–EDS microstructural analysis revealed a uniform distribution of chromium and manganese within the metallic matrix, indicating stable reduction behavior and favorable melt crystallization conditions. The obtained results demonstrate the effectiveness of an integrated thermodynamic–experimental approach for producing chromium–manganese ligatures from low-grade mineral raw materials and industrial by-products and confirm the potential applicability of the proposed process for complex steel alloying. Full article

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13 pages, 2615 KB

Open AccessArticle

The Effect of Post-Heat Treatments on Microstructure and Mechanical Properties of a L-PBF CoCrNi–AlTi Medium-Entropy Alloy

by Xiaojing Xiong, Xiaodong Nong, Libin Yu, Xianzhao Meng, Chunjia Mo, Yunjie Bi and Hui Ding

Metals 2026, 16(2), 183; https://doi.org/10.3390/met16020183 - 3 Feb 2026

Abstract

A CoCrNi-AlTi medium-entropy alloy was fabricated via laser powder bed fusion (L-PBF), and its microstructural evolution and mechanical response during aging at 500–900 °C for 1 h were systematically investigated. The as-built alloy exhibits a hierarchical microstructure consisting of elongated columnar grains and [...] Read more.

A CoCrNi-AlTi medium-entropy alloy was fabricated via laser powder bed fusion (L-PBF), and its microstructural evolution and mechanical response during aging at 500–900 °C for 1 h were systematically investigated. The as-built alloy exhibits a hierarchical microstructure consisting of elongated columnar grains and dislocation-rich cellular substructures, which is associated with an excellent strength–ductility combination (YS: 848 MPa, UTS: 1136 MPa, EF: 32.6%). Upon aging, a pronounced precipitation-hardening response is observed, with a peak hardness of 501 ± 7 HV and an ultimate tensile strength of 1429 MPa achieved at 800 °C. TEM and STEM-EDS analyses indicate that Ti preferentially segregates along dislocation networks and grain boundaries at early aging stages, promoting the heterogeneous nucleation of nanoscale Ni–Al–Ti–rich precipitates that effectively impede dislocation motion. At elevated aging temperatures, additional Cr-enriched regions with diffuse compositional partitioning are observed within the FCC matrix, occurring concurrently with the peak mechanical performance. Further aging at 900 °C leads to strength degradation, which is attributed to precipitate coarsening and recovery-induced dislocation annihilation. These results highlight the critical role of L-PBF-induced defect structures in governing precipitation behavior and the resulting strength–ductility trade-off during post-build heat treatment of CoCrNi-AlTi medium-entropy alloys. Full article

(This article belongs to the Special Issue Additive Manufacturing of Metallic Materials)

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1 pages, 469 KB

Open AccessCorrection

Correction: Ma et al. Enhanced Generative Adversarial Networks for Isa Furnace Matte Grade Prediction Under Limited Data. Metals 2024, 14, 916

by Huaibo Ma, Zhuorui Li, Bo Shu, Bin Yu and Jun Ma

Metals 2026, 16(2), 182; https://doi.org/10.3390/met16020182 - 3 Feb 2026

Abstract

In the original publication [...] Full article

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17 pages, 3093 KB

Open AccessArticle

Different Effects of Varying Cryogenic Temperatures on Different Properties of a Biocompatible Mg-10Se Alloy

by Jiaqi Chen, Michael Johanes and Manoj Gupta

Metals 2026, 16(2), 181; https://doi.org/10.3390/met16020181 - 3 Feb 2026

Abstract

Mg has high potential as a base metal for biocompatible metallic implants due to its light weight, biocompatibility, and mechanical properties that are similar to bone. In the present study, Mg-10Se was synthesized via a powder metallurgy method followed by cryogenic treatment (CT). [...] Read more.

Mg has high potential as a base metal for biocompatible metallic implants due to its light weight, biocompatibility, and mechanical properties that are similar to bone. In the present study, Mg-10Se was synthesized via a powder metallurgy method followed by cryogenic treatment (CT). It was found that cryogenic exposure to −20 °C (RF20) resulted in the best combination of damping properties (38.5% and 12.1% gains in attenuation coefficient and damping capacity, respectively) and compressive yield strength (16.7%), while liquid nitrogen (LN) treatment (−196 °C) resulted in the best ultimate compressive strength (10% increase to 260 MPa), energy absorbed during compressive testing (17.5% increase to 40 MJ/m³), and optimal corrosion rate (reduction of 59.7% to 0.273 mm/year). This study clearly highlights the role and importance of not just compositional control in improving properties but that of cryogenic treatment temperature to selectively enhance the individual properties of metallic materials to best meet end application requirements. Full article

(This article belongs to the Special Issue Biodegradable and Biobased Metallic Materials: Design, Processing, Applications)

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23 pages, 19417 KB

Open AccessArticle

The Role of the Magnetic Field Orientation and Strength on the Electrodeposition of Ni-Fe Bifunctional Electrocatalyst for Hydrogen Evolution Reaction and Oxygen Evolution Reaction

by Safya Elsharkawy, Mateusz M. Marzec and Piotr Żabiński

Metals 2026, 16(2), 180; https://doi.org/10.3390/met16020180 - 3 Feb 2026

Abstract

Ni–Fe alloys were prepared via electrodeposition from a citrate electrolyte under different magnetic field (MF) strengths (0.1 T, 0.3 T, and 0.5 T) and configurations parallel (B_‖) and perpendicular (B_⊥) to the electrode surface. The magnetohydrodynamics (MHD) induced by [...] Read more.

Ni–Fe alloys were prepared via electrodeposition from a citrate electrolyte under different magnetic field (MF) strengths (0.1 T, 0.3 T, and 0.5 T) and configurations parallel (B_‖) and perpendicular (B_⊥) to the electrode surface. The magnetohydrodynamics (MHD) induced by the magnetic field influences their structural, compositional, and electrocatalytic properties. The application of an external homogeneous magnetic field significantly altered the alloy morphology, composition, and crystallinity, which we investigated. Scanning electron microscopy (SEM) and X-ray fluorescence (XRF) studies reflected that moderate MF intensity (0.3 T) led to modest variation in Fe incorporation and produced smoother, denser, and more homogeneous Ni–Fe films, particularly under (B_⊥), while high field strength (0.5 T) resulted in surface roughening and compositional nonuniformity. X-ray diffraction (XRD) confirmed that the perpendicular MF enhanced crystallinity and favored (111) and (200) texture growth, while parallel orientation led to weaker and broader diffraction peaks, providing less-ordered growth. Furthermore, slight variations in Fe content were observed with changes in magnetic field strength and direction. Electrochemical measurements demonstrated that the deposited Ni-Fe under various magnetic field conditions modulated both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in 1 M NaOH. For HER, the lowest overpotential (η₁₀ = −227 mV at 10 mA cm⁻²) and Tafel slope (120 mV·dec⁻¹) were obtained for the deposited Ni-Fe under (B_‖) at 0.1 T, while for OER, the best catalytic performance occurred for fabricated Ni-Fe alloy under (B_⊥) at 0.3 T with an overpotential value of (η₁₀ = 320 mV, Tafel = 202 mV·dec⁻¹). The deposited Ni-Fe alloys under both orientations exhibited reasonable stability and durability during a prolonged operation process. Overall, the findings demonstrate that controlling magnetic field orientation and intensity during electrodeposition provides a versatile route to tailor the microstructure and optimize the bifunctional electrocatalytic performance of Ni–Fe alloys for the water-splitting reaction in an alkaline medium. Full article

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27 pages, 4367 KB

Open AccessArticle

MTFE-Net: A Deep Learning Vision Model for Surface Roughness Extraction Based on the Combination of Texture Features and Deep Learning Features

by Qiancheng Jin, Wangzhe Du, Huaxin Liu, Xuwei Li, Xiaomiao Niu, Yaxing Liu, Jiang Ji, Mingjun Qiu and Yuanming Liu

Metals 2026, 16(2), 179; https://doi.org/10.3390/met16020179 - 2 Feb 2026

Abstract

Surface roughness, critically measured by the Arithmetical Mean Roughness (Ra), is a vital determinant of workpiece functional performance. Traditional contact-based measurement methods are inefficient and unsuitable for online inspection. While machine vision offers a promising alternative, existing approaches lack robustness, and pure deep [...] Read more.

Surface roughness, critically measured by the Arithmetical Mean Roughness (Ra), is a vital determinant of workpiece functional performance. Traditional contact-based measurement methods are inefficient and unsuitable for online inspection. While machine vision offers a promising alternative, existing approaches lack robustness, and pure deep learning models suffer from poor interpretability. Therefore, MTFE-Net is proposed, which is a novel deep learning framework for surface roughness classification. The key innovation of MTFE-Net lies in its effective integration of traditional texture feature analysis with deep learning within a dual-branch architecture. The MTFE (Multi-dimensional Texture Feature Extraction) branch innovatively combines a comprehensive suite of texture descriptors including Gray-Level Co-occurrence Matrix (GLCM), gray-level difference statistic, first-order statistic, Tamura texture features, wavelet transform, and Local Binary Pattern (LBP). This multi-scale, multi-perspective feature extraction strategy overcomes the limitations of methods that focus on only specific texture aspects. These texture features are then refined using Multi-Head Self-Attention (MHA) mechanism and Mamba model. Experiments on a dataset of Q235 steel surfaces show that MTFE-Net achieves state-of-the-art performance with 95.23% accuracy, 94.89% precision, 94.67% recall and 94.74% F1-score, significantly outperforming comparable models. The results validate that the fusion strategy effectively enhances accuracy and robustness, providing a powerful solution for industrial non-contact roughness inspection. Full article

(This article belongs to the Section Computation and Simulation on Metals)

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17 pages, 2423 KB

Open AccessArticle

Assessing the Potential of Heterotrophic Bioleaching to Extract Metals from Mafic Tailings

by Kamalpreet Kaur Brar, Avi Du Preez and Nancy N. Perreault

Metals 2026, 16(2), 178; https://doi.org/10.3390/met16020178 - 2 Feb 2026

Abstract

Mafic mine tailings are highly resistant to bioleaching due to their silicate-rich composition, low sulfide content, and strong buffering capacity. This study aimed to assess the potential use of heterotrophic bioleaching to promote the release of metals from mafic tailings by evaluating the [...] Read more.

Mafic mine tailings are highly resistant to bioleaching due to their silicate-rich composition, low sulfide content, and strong buffering capacity. This study aimed to assess the potential use of heterotrophic bioleaching to promote the release of metals from mafic tailings by evaluating the organic acid production and leaching capabilities of indigenous bacterial isolates and a known lactic acid producer, Lactiplantibacillus plantarum ATCC 8014. Indigenous acid-producing heterotrophic bacteria were isolated from a vanadium-titanium-bearing magnetite tailings in Québec, Canada, and screened for organic acid production in various culture media. The most active bacteria were L. plantarum and two isolates identified by their 16S rRNA gene as Enterococcus (CBGM-1C) and Acetobacter (BL-F) sp. They produced significant quantities of lactic acids, followed by acetic, citric, and gluconic acids during glucose metabolism, through fermentative or oxidative pathways. A two-step bioleaching process was implemented, consisting of an initial organic acid production phase followed by tailings leaching at 5% pulp density over 10 days at 30 °C. Metal solubilization and mineralogical analyses demonstrated strain-dependent and metal-specific mobilization, with zinc being the only element efficiently leached (up to ~74% recovery by L. plantarum). XRD analyses confirmed partial dissolution and reduced crystallinity of key silicate phases without secondary mineral formation. These findings indicate that heterotrophic leaching can selectively mobilize more labile metals such as Zn from alkaline, silicate-rich tailings, although its overall efficiency for refractory elements remains limited under the tested conditions. Full article

(This article belongs to the Special Issue Metal Extraction and Recovery from Slag: Separation and Reduction Processes)

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