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Volume 15
Issue 12
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Metals, Volume 15, Issue 12 (December 2025) – 114 articles

Cover Story (view full-size image): This work demonstrates an effective Direct Energy Deposition strategy for fabricating crack-free Inconel 718–copper bimetallic structures, overcoming the large thermophysical mismatch between the two alloys. By depositing In718 directly onto a copper substrate with tailored process control, strong diffusion bonding and defect-free interfaces were achieved without post-processing. Microstructural analyses revealed uniform precipitate distribution and consistent penetration depth, while mechanical testing confirmed enhanced hardness, creep resistance, and interfacial integrity. Notably, precipitation strengthening occurred on the copper side already in the as-built condition. The proposed approach enables reliable, high-performance In718–Cu components for demanding aerospace and thermal-management applications. View this paper
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20 pages, 6996 KB  
Article
Influence of Surface Finishing on the Corrosion and Wear Behaviour of AISI 304 and AISI 436 Stainless Steels
by Silvia Gómez, Ismael Lamas, Alejandro Pereira and M. Consuelo Pérez
Metals 2025, 15(12), 1390; https://doi.org/10.3390/met15121390 - 18 Dec 2025
Viewed by 258
Abstract
The pitting corrosion resistance and the tribological behaviour of a ferritic stainless steel with high Mo content (AISI 436) and a commonly employed austenitic stainless steel (AISI 304) are compared. Special attention was paid to the role of Mo in improving corrosion resistance [...] Read more.
The pitting corrosion resistance and the tribological behaviour of a ferritic stainless steel with high Mo content (AISI 436) and a commonly employed austenitic stainless steel (AISI 304) are compared. Special attention was paid to the role of Mo in improving corrosion resistance of ferritic stainless steels. Since the surface condition is an important parameter related to the onset of pitting corrosion in the presence of chlorides, three different surface finishes were tested for both steels. Two commercial finishing grades and laboratory polishing down to 1 µm were compared. Moreover, the influence of surface condition on the tribological properties for both steels was also evaluated. The study demonstrates that surface finishing plays a decisive role in both the electrochemical and mechanical response of stainless steels. A comprehensive microstructural and tribological analysis reveals not only how commercial finishing treatments modify passive film behaviour, but also how they affect friction stability and wear mechanisms. Special emphasis is placed on the synergistic effect between molybdenum content, passive film integrity and manufacturing processes. The obtained results provide valuable insight for industrial applications where durability against chloride exposure and abrasion is critical. Full article
(This article belongs to the Special Issue Corrosion Behavior of Carbon Steels in Natural and Industrial Environments—3rd Edition)
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13 pages, 2505 KB  
Article
An Experimental Investigation of the Influence of Deposition Power and Pressure on the Anti-Icing and Wettability Properties of Al-Doped ZnO Thin Films Prepared by Magnetron Sputtering
by Vandan Vyas, Kamlesh V. Chauhan, Sushant Rawal and Noor Mohammad Mohammad
Metals 2025, 15(12), 1389; https://doi.org/10.3390/met15121389 - 18 Dec 2025
Viewed by 215
Abstract
In the presented research, aluminum-doped zinc oxide (AZO) thin films were synthesized on high-power transmission lines using the RF magnetron sputtering process. The impact of deposition power (160 W to 280 W) and deposition pressure (2 Pa to 5 Pa), on key characteristics [...] Read more.
In the presented research, aluminum-doped zinc oxide (AZO) thin films were synthesized on high-power transmission lines using the RF magnetron sputtering process. The impact of deposition power (160 W to 280 W) and deposition pressure (2 Pa to 5 Pa), on key characteristics like material composition, wettability, anti-icing behavior, and average crystal size were analyzed. The optimization of wettability and anti-icing performance was carried out using two-factor, four-level design of the Taguchi method to study the combined effects of multiple parameters rather than the effect of a single parameter. Considerable variation in the water contact angle, from 92.3° to 123.6°, has been observed, suggesting an enhancement in hydrophobic nature with optimized condition. Anti-icing tests demonstrated that the coated surface delayed ice accumulation by approximately 4.56 times compared to the uncoated surface. X-ray diffraction (XRD) analysis was carried out to confirm notable changes in the intensity of the (002) peak along the c-axis, directly correlating with grain size modification. The change in surface roughness was studied using AFM and the results were compared to establish a relationship between surface roughness and average grain size. Overall, the findings highlight the critical role of deposition parameters and their interactions in modifying the surface and structural properties of AZO thin films, which demonstrates their potential application for improving the anti-icing performance of transmission lines. Full article
(This article belongs to the Special Issue Surface Treatments and Coating of Metallic Materials)
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15 pages, 8848 KB  
Article
Optimization of a Center-Punching Mechanical Clinching Process for High-Strength Steel DP980 and Aluminum Alloy AL5052 Sheets
by Ping Qiu, Xiaoxin Lu, Boran Deng, Hong Xiao and Chao Yu
Metals 2025, 15(12), 1388; https://doi.org/10.3390/met15121388 - 18 Dec 2025
Viewed by 202
Abstract
As research on new, lightweight energy vehicles continues to develop, the application of high-strength steel sheets with tensile strength greater than 1 GPa and their mechanical clinching technology, which is associated with aluminum alloys, has emerged as a new research focus. However, due [...] Read more.
As research on new, lightweight energy vehicles continues to develop, the application of high-strength steel sheets with tensile strength greater than 1 GPa and their mechanical clinching technology, which is associated with aluminum alloys, has emerged as a new research focus. However, due to the challenges associated with the cold deformation of high-strength steel, conventional mechanical clinching processes often fail to establish effective joint interlocking, resulting in weak connections. This study proposes a center-punching mechanical clinching process for connecting DP980 high-strength steel to AL5052 aluminum alloy. The mechanical evolution during the forming process was analyzed via finite element simulation. An orthogonal experimental design was employed to optimize key geometric parameters of the punch and die, yielding the optimal configuration for the mold. Mechanical testing of the joint demonstrated average pull-out force and pull-shear forces of 1124 N and 2179 N, respectively, confirming the proposed process’s ability to successfully connect high-strength steel and aluminum alloy. Full article
(This article belongs to the Special Issue Manufacturing Processes of Metallic Materials (2nd Edition))
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17 pages, 4340 KB  
Article
Corrosion Behavior upon Laser Surface Texturing AISI 430 Stainless Steel
by Edit Roxana Moldovan, Liana Sanda Baltes, Catalin Croitoru, Alexandru Pascu and Mircea Horia Tierean
Metals 2025, 15(12), 1387; https://doi.org/10.3390/met15121387 - 18 Dec 2025
Viewed by 238
Abstract
Laser surface texturing (LST) is an effective method for enhancing surface functionality, but its effect on corrosion resistance highly depends on texture design and processing parameters. This study investigates the influence of two LST patterns—orthogonal ellipses and concentric octo-donuts—applied with 1 to 20 [...] Read more.
Laser surface texturing (LST) is an effective method for enhancing surface functionality, but its effect on corrosion resistance highly depends on texture design and processing parameters. This study investigates the influence of two LST patterns—orthogonal ellipses and concentric octo-donuts—applied with 1 to 20 repetitions on the corrosion resistance of AISI 430 ferritic stainless steel. Corrosion behavior was evaluated using potentiodynamic polarization in a 3.5 wt.% NaCl solution at room temperature, complemented by SEM and EDS analysis. The results indicate that while a single laser pass can maintain good corrosion resistance, increasing the number of repetitions significantly degrades performance. This is attributed to the disruption of the protective oxide layer, the introduction of residual stress, and the creation of localized sites for galvanic corrosion. Consequently, the study concludes that a low number of laser repetitions is crucial for preserving the corrosion resistance of LST-processed AISI 430 steel. Full article
(This article belongs to the Special Issue Surface Treatments and Coating of Metallic Materials)
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16 pages, 3563 KB  
Article
Multiple Diffraction in a Basic Co-Rich Decagonal Al-Co-Ni Quasicrystal
by Changzeng Fan
Metals 2025, 15(12), 1386; https://doi.org/10.3390/met15121386 - 18 Dec 2025
Viewed by 347
Abstract
To reveal its influence on quasicrystal structure analysis, multiple diffraction 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 in the in-house measurements, and 40° ψ-scans [...] Read more.
To reveal its influence on quasicrystal structure analysis, multiple diffraction 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 in the in-house measurements, and 40° ψ-scans of one main reflection have been performed with synchrotron radiation. As well as being known for periodic crystals and the icosahedral quasicrystal, it is also observed for this decagonal quasicrystal that the intensity of the main reflection may significantly increase if the simultaneous and the coupling reflections are both strong. The occurrence of multiple diffraction 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 multiple diffraction theory. The present experimental and simulation efforts on the effects of multiple diffraction suggest that it is insufficient on its own to explain the discrepancy in weak-reflection intensities; alternative explanations like the phasonic disorder should be paid more attention in future. Full article
(This article belongs to the Special Issue Research Progress of Crystal in Metallic Materials)
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15 pages, 3343 KB  
Article
Effect of Solidification Conditions on High-Cycle Fatigue Behavior in DD6 Single-Crystal Superalloy
by Hongji Xie, Yushi Luo, Yunsong Zhao and Zhenyu Yang
Metals 2025, 15(12), 1385; https://doi.org/10.3390/met15121385 - 17 Dec 2025
Viewed by 255
Abstract
This study investigates the influence of solidification conditions on the high-cycle fatigue (HCF) behavior of a second-generation DD6 single-crystal superalloy. Single-crystal bars with a [001] orientation were prepared using the high-rate solidification (HRS) and liquid-metal cooling (LMC) techniques under various pouring temperatures. The [...] Read more.
This study investigates the influence of solidification conditions on the high-cycle fatigue (HCF) behavior of a second-generation DD6 single-crystal superalloy. Single-crystal bars with a [001] orientation were prepared using the high-rate solidification (HRS) and liquid-metal cooling (LMC) techniques under various pouring temperatures. The HCF performance of the heat-treated alloy was subsequently evaluated at 800 °C using rotary bending fatigue tests. The results demonstrate that increasing the pouring temperature effectively reduced the content and size of microporosity in the HRS alloys. At an identical pouring temperature, the LMC alloy exhibited a significant reduction in microporosity, with its content and maximum pore size being only 44.4% and 45.8% of those in the HRS alloy, respectively. Consequently, the HCF performance was enhanced with increasing pouring temperature for the HRS alloys. The LMC alloy outperformed its HRS counterpart processed at the same temperature, showing a 9.4% increase in the conditional fatigue limit (at 107 cycles). Microporosity was identified as the dominant site for HCF crack initiation at 800 °C. The role of γ/γ′ eutectic in crack initiation diminished or even vanished as the solidification conditions were optimized. Fractographic analysis revealed that the HCF fracture mechanism was quasi-cleavage, independent of the solidification conditions. Under a typical stress amplitude of 550 MPa, the deformation mechanism was characterized by the slip of a/2<011> dislocations within the γ matrix channels, which was also unaffected by the solidification conditions. In conclusion, optimizing solidification conditions, such as by increasing the pouring temperature or employing the LMC process, enhances the HCF performance of the DD6 alloy primarily by refining microporosity, which in turn prolongs the fatigue crack initiation life. Full article
(This article belongs to the Section Metal Failure Analysis)
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34 pages, 4462 KB  
Article
Data-Driven Method for Predicting S-N Curve Based on Structurally Sensitive Fatigue Parameters
by Andrey Kurkin, Alexander Khrobostov, Vyacheslav Andreev and Olga Andreeva
Metals 2025, 15(12), 1384; https://doi.org/10.3390/met15121384 - 17 Dec 2025
Viewed by 196
Abstract
Under cyclic loading, almost immediately after its onset, a surface layer forms where hardening and softening processes occur. The interaction of plastic deformation traces with each other, and with other structural elements, leads to the formation of a characteristic microstructure on the surface [...] Read more.
Under cyclic loading, almost immediately after its onset, a surface layer forms where hardening and softening processes occur. The interaction of plastic deformation traces with each other, and with other structural elements, leads to the formation of a characteristic microstructure on the surface of a component subjected to cyclic loading. The set of factors (conditions) acting during cyclic loading determines the nature of slip band accumulation, the integral structurally sensitive fatigue parameter, expressed as the slope of the left side of the fatigue curve linearized in logarithmic coordinates, and the location of the breaking point on the fatigue curve in the high-cycle region. A combined review of numerous data on the fatigue of metals, obtained under various combinations of factors, and the generalization of these results through a normalization procedure for obtaining the relative (recalculated) parameters of fatigue, allows us to derive a universal method for “S-N” curve prediction. However, extensive generalization decreases the prediction accuracy for specific cases; therefore, it is proposed to form limited generalized dependencies corresponding to specific operating conditions. This paper evaluates the accuracy of fatigue limit prediction using generalized and limited-generalized relationships of fatigue recalculated parameters for various fatigue curves obtained from independent experimental data. Full article
(This article belongs to the Special Issue Fatigue, Fracture, and Multiaxial Integrity of Metallic Structure Materials: From Microstructure to Data-Driven Assessment)
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26 pages, 2995 KB  
Review
Research Progress on Application of Machine Learning in Continuous Casting
by Zhaofeng Wang, Jinghao Shao, Shuai Zhang, Jiahui Zhang and Yuqi Pang
Metals 2025, 15(12), 1383; https://doi.org/10.3390/met15121383 - 17 Dec 2025
Viewed by 387
Abstract
Continuous casting is a key core link in steel production with characteristics of strong nonlinearity, multi-parameter coupling and dynamic fluctuations under working conditions. Traditional experience-dependent or mechanism-driven models are no longer suitable for the high-quality and high-efficiency production demands of modern steel industries. [...] Read more.
Continuous casting is a key core link in steel production with characteristics of strong nonlinearity, multi-parameter coupling and dynamic fluctuations under working conditions. Traditional experience-dependent or mechanism-driven models are no longer suitable for the high-quality and high-efficiency production demands of modern steel industries. Machine learning provides an effective technical path for solving the complex control problems in the continuous casting process through its powerful data mining and pattern recognition capabilities. This paper systematically reviews the research progress of machine learning applications in the field of continuous casting, focusing on three core scenarios: abnormal prediction, quality defect detection and process parameter optimization. It sorts out the evolution from single models to feature optimization and integration, deep learning hybrid models, and mechanism-data dual-driven models. It summarizes the significant achievements of this technology in reducing production risks and improving the stability of cast billet quality, and it analyzes the prominent challenges currently faced such as data distortion and distribution imbalance, insufficient model interpretability and limited cross-scenario generalization ability. Finally, it looks forward to future technological innovation and application expansion directions, providing theoretical support and technical references for the digital and intelligent transformation of the steel industry. Full article
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12 pages, 17551 KB  
Article
Ni-Driven Martensitic Packet Refinement to Improve the Low-Temperature Impact Toughness of Simulated CGHAZ in High-Strength Steel
by Guodong Zhang, Zhongzhu Liu, Xuelin Wang, Lixia Li, Yuanyuan Li and Yanli Yang
Metals 2025, 15(12), 1382; https://doi.org/10.3390/met15121382 - 17 Dec 2025
Viewed by 180
Abstract
The effect of Ni content on the improvement of low-temperature impact toughness and microstructure refinement in a simulated coarse-grained heat-affected zone (CGHAZ) of high-strength steel was studied. The impact toughness tests revealed that as the heat input increased from 20 to 50 kJ/cm, [...] Read more.
The effect of Ni content on the improvement of low-temperature impact toughness and microstructure refinement in a simulated coarse-grained heat-affected zone (CGHAZ) of high-strength steel was studied. The impact toughness tests revealed that as the heat input increased from 20 to 50 kJ/cm, both low-nickel (L-Ni) steel and high-nickel (H-Ni) steel exhibited a rapid decline in the impact toughness of their coarse-grained heat-affected zones (CGHAZ), though the H-Ni steel consistently demonstrated significantly higher impact toughness than the L-Ni steel. Microstructural characterization showed that the microstructure of L-Ni steel gradually transitioned from lath bainite (LB) to granular bainite (GB) with increasing heat input, which accounted for its reduced impact toughness. Conversely, H-Ni steel underwent a phase transformation from lath martensite (LM) to LB with increasing heat input, showing an unexpected trend opposite to the conventional understanding of toughness enhancement. Notably, the martensitic structure obtained in H-Ni steel at 20 kJ/cm exhibited substantially higher impact energy (59.6 J) than both the LB structures of L-Ni steel (44.6 J) and those of H-Ni steel (37.8 J) observed at 20 and 50 kJ/cm heat inputs. This phenomenon is attributed to the increased Ni content significantly refining the packet of LM, thereby enhancing its resistance to brittle crack propagation. Although LB structures obtained under different conditions exhibited refined blocks, their parallel arrangement within coarse packets resulted in less effective obstruction of brittle crack propagation compared to the refined packet with interlocking arrangement. Full article
(This article belongs to the Special Issue Advances in Welding and Joining of Alloys and Steel)
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16 pages, 10448 KB  
Article
Combined Centrifugal Casting–Self-Propagating High-Temperature Synthesis Process of High-Entropy Alloys FeCoNiCu(Me)Al (Me = Cr, Cr + Mn, Cr + La, and Cr + Ce) as Precursors for Preparation of Deep Oxidation Catalysts
by Elena Pugacheva, Denis Ikornikov, Alina Sivakova, Ksenia Romazeva, Dmitrii Andreev, Olga Golosova, Vyacheslav Borshch and Vladimir Sanin
Metals 2025, 15(12), 1381; https://doi.org/10.3390/met15121381 - 16 Dec 2025
Viewed by 325
Abstract
FeCoNiCu(Cr, Mn, La, Ce)-Al high-entropy alloys (HEAs) were prepared via a combined centrifugal casting–self-propagating high-temperature synthesis process to serve as multifunctional catalyst precursors. The findings indicated that even with aluminum content reaching 50 wt %, the typical bcc structure inherent to HEAs was [...] Read more.
FeCoNiCu(Cr, Mn, La, Ce)-Al high-entropy alloys (HEAs) were prepared via a combined centrifugal casting–self-propagating high-temperature synthesis process to serve as multifunctional catalyst precursors. The findings indicated that even with aluminum content reaching 50 wt %, the typical bcc structure inherent to HEAs was preserved. Doping additions (Cr, Mn, La, and Ce) led to pronounced microstructural changes, including alterations in morphology, porosity, and elemental distribution, while the primary phase constituents of the FeCoNiCuAl-based alloys remained consistent. It was found that La and Ce exhibited poor bulk incorporation into the HEAs, evidenced by a low surface content. Aluminum leaching and hydrogen peroxide stabilization converted these precursors into catalysts. These catalysts demonstrated high activity in the deep oxidation of propane and CO. The FeCoNiCu catalyst achieved the best results for CO oxidation, reaching 100% CO conversion at 250 °C. For propane oxidation, the FeCoNiCuCrMn catalyst was the most active, yielding 100% CO conversion at 300 °C and 97% propane conversion at 400 °C. Full article
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20 pages, 5675 KB  
Article
Deep Learning-Based Automatic Recognition of Segregation in Continuous Casting Slabs
by Xiaojuan Wu, Jiwu Zhang, Fujian Guo, R. Devesh Kumar Misra, Xuemin Wang and Xiucheng Li
Metals 2025, 15(12), 1380; https://doi.org/10.3390/met15121380 - 16 Dec 2025
Viewed by 234
Abstract
Central segregation, a typical internal defect in continuous casting slabs, significantly deteriorates the mechanical properties of steel products. However, traditional manual defect evaluation methods rely heavily on experience, are highly subjective and inefficient, making it difficult to meet the quality assessment requirements of [...] Read more.
Central segregation, a typical internal defect in continuous casting slabs, significantly deteriorates the mechanical properties of steel products. However, traditional manual defect evaluation methods rely heavily on experience, are highly subjective and inefficient, making it difficult to meet the quality assessment requirements of today’s high-end steel materials. In this study, an approach which combines an unsupervised image enhancement algorithm and Otsu algorithm analysis was proposed to achieve automatic recognition and quantitative features extracting of central segregation in continuous casting slabs. The challenges posed by insufficient brightness and low contrast in central segregation images were addressed using unsupervised image enhancement algorithms. Following this enhancement, batch objective quantification of the segregation images was conducted through Otsu processing. Comparative experimental results showed that the enhanced images yielded an average Dice Similarity Coefficient of 0.965 for segregation recognition, representing a 38% improvement over unprocessed images, with consistent accuracy gains across complex segregation scenarios. This intelligent detection method eliminates the need for manually labeling a training set, substantially improves the consistency of segregation quantification and reduces the time cost significantly. Consequently, multiple parameters can be employed to quantify segregation characteristics, offering a more comprehensive and precise approach than current simplified rating methods. This advancement holds promise for enhancing quality control in steel processing and advancing Artificial Intelligence-driven technological progress within the metallurgical sector. Full article
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22 pages, 22239 KB  
Article
Computational Modeling of Multiple-Phase Transformations in API X70 and X80 Steels
by Ry Karl, Jonas Valloton, Chad Cathcart, Tihe Zhou, Fateh Fazeli, J. Barry Wiskel and Hani Henein
Metals 2025, 15(12), 1379; https://doi.org/10.3390/met15121379 - 16 Dec 2025
Viewed by 306
Abstract
Continuous cooling transformation (CCT) diagrams for two thermo-mechanically controlled processed (TMCP) steels were produced using a modified Johnson–Mehl–Avrami–Kolmogorov (JMAK) model, which accounted for the simultaneous transformation of multiple phases under non-isothermal conditions. A basin hopping algorithm was used to sequentially optimize the model [...] Read more.
Continuous cooling transformation (CCT) diagrams for two thermo-mechanically controlled processed (TMCP) steels were produced using a modified Johnson–Mehl–Avrami–Kolmogorov (JMAK) model, which accounted for the simultaneous transformation of multiple phases under non-isothermal conditions. A basin hopping algorithm was used to sequentially optimize the model parameters for each phase. Samples were prepared using a dilatometer which replicated the deformation and cooling rates experienced during TMCP. Scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD) were used to identify and quantify the phases present in each steel. CCT diagrams illustrating the start and stop temperatures of each phase were constructed for both steel samples. Through inclusion of the stop temperatures of each phase transformation, the utility of the CCT diagrams were expanded. This was done by introducing the possibility of applying the Scheil additive principle with respect to the beginning and end of each phase transformation. With this modification, the CCT diagrams are now more appropriately suited to predict the phase transformations that occur on the ROT, where non-continuous cooling occurs. Full article
(This article belongs to the Section Metal Casting, Forming and Heat Treatment)
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21 pages, 6680 KB  
Article
Interactions Effect Among the Electrolytes on Micro-Arc Oxidation Coatings of AZ91D Mg Alloy
by Zhanying Wang, Qinqin Zhao, Ying Ma, Leichao Meng and Lingyun An
Metals 2025, 15(12), 1378; https://doi.org/10.3390/met15121378 - 16 Dec 2025
Viewed by 194
Abstract
Simplex-centroid mixture design (SCMD) is applied to change the combination of Na2SiO3, KF, NaOH and NaAlO2 to examine the influences of electrolyte components and their interactions on the thickness and corrosion resistance of micro-arc oxidation (MAO) coating of [...] Read more.
Simplex-centroid mixture design (SCMD) is applied to change the combination of Na2SiO3, KF, NaOH and NaAlO2 to examine the influences of electrolyte components and their interactions on the thickness and corrosion resistance of micro-arc oxidation (MAO) coating of AZ91D magnesium alloy. The results indicate that the obtained regression equations are very significant (p-value < 0.01) and have high prediction accuracy (R2 = 0.9893, 0.9989). Pareto analysis shows that the interactions effect between Na2SiO3, KF and NaAlO2 on the coating thickness and corrosion resistance are 70.03% and 92.35%, respectively, which quantitatively confirms that there are interactions among electrolytes. The analysis of response surface methodology (RSM) demonstrates that the optimum formula is high concentration of Na2SiO3, high concentration of KF and low concentration of NaAlO2. When Na2SiO3 is compounded with NaAlO2, the two will react to form aluminosilicate colloids, resulting in increased viscosity of the electrolyte, and the coating corrosion resistance is poor. When the main salt of electrolyte is single Na2SiO3 or NaAlO2, the corrosion resistance is better. KF can significantly improve the coating thickness and corrosion resistance. Pearson correlation coefficient (PCC) reveals that there is a remarkable relationship between thickness and the corrosion resistance in acidic media (r = 0.88927), which was determined by the corrosion mechanism of the latter. Full article
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4 pages, 690 KB  
Correction
Correction: Vidal-Crespo et al. Mechanical Amorphization and Recrystallization of Mn-Co(Fe)-Ge Compositions. Metals 2019, 9, 534
by Antonio Vidal-Crespo, Jhon J. Ipus, Javier S. Blázquez and Alejandro Conde
Metals 2025, 15(12), 1377; https://doi.org/10.3390/met15121377 - 16 Dec 2025
Viewed by 130
Abstract
There was an error in the original publication [...] Full article
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16 pages, 4411 KB  
Article
Determination of Damage Constant and Critical Damage by the Combined Experiment and FEM Using the Reference Processes
by Boseung Hong, Hyeonmin Lee, Seokmoo Hong and Mansoo Joun
Metals 2025, 15(12), 1376; https://doi.org/10.3390/met15121376 - 15 Dec 2025
Viewed by 192
Abstract
The practical characterization algorithm is presented to find the optimized damage constants and critical damages of the traditional damage models formulated by some unknown damage constants. The flow characterization of the material SWCH45F is conducted using the combined finite element method (FEM) and [...] Read more.
The practical characterization algorithm is presented to find the optimized damage constants and critical damages of the traditional damage models formulated by some unknown damage constants. The flow characterization of the material SWCH45F is conducted using the combined finite element method (FEM) and experimental method, assisted by elastoplastic finite element (FE) analysis of a cylindrical tensile test with accuracy. The new concept of a critical edge length of FEs is proposed to overcome the highly negative situations caused by the remeshing during a bulk metal-forming simulation for reliable damage prediction. With accurate flow behavior and optimized numerical conditions, two examples of bulk metal-forming processes, including the tensile test and bolt heading process (all are clear in the fracture perspective), are then simulated to reveal the relationship between the damage constant and maximum damage, which is employed to determine the damage constant and the critical damage. This approach is successfully used to optimally calculate the damage constant of the generalized Huh’s damage model along with the critical damage. The generality and practicality of the new approach are emphasized. Full article
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30 pages, 12283 KB  
Article
A Novel Mathematical Model for Predicting Self-Excited Vibrations in Micromilling of Aluminium 7075
by Cvijetin Mladjenovic, Dejan Marinković, Katarina Monkova, Miloš Knežev and Aleksandar Živković
Metals 2025, 15(12), 1375; https://doi.org/10.3390/met15121375 - 15 Dec 2025
Viewed by 246
Abstract
Micro milling of metallic materials presents unique dynamic challenges due to highly nonlinear cutting forces and the susceptibility to self-excited vibrations (chatter). This paper presents a novel mathematical model for chatter prediction in micro milling, based on an enhanced formulation of cutting forces [...] Read more.
Micro milling of metallic materials presents unique dynamic challenges due to highly nonlinear cutting forces and the susceptibility to self-excited vibrations (chatter). This paper presents a novel mathematical model for chatter prediction in micro milling, based on an enhanced formulation of cutting forces that includes the frictional interaction between the tool’s flank face and the machined surface. The proposed approach enables accurate simulation of the cutting process and prediction of the limiting depth of cut, beyond which chatter occurs. Experimental validation was performed using pneumatic spindle and micro end mills, with chatter detection based on surface inspection via digital microscopy. A strong correlation was observed between the simulated and experimentally determined limiting depths of cut, confirming the model’s predictive capability. This research offers a new methodology for modelling cutting forces and improves the ability to predict chatter in micro milling processes, contributing to the optimization of machining parameters across a wide range of materials. Full article
(This article belongs to the Special Issue Computational Methods in Metallic Materials Manufacturing Processes 2025)
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13 pages, 7244 KB  
Article
Surface Integrity and Corrosion Resistance of Additively Manufactured AZ91 Mg Alloys Post-Processed by Laser Shock Peening
by Shan Gao, Wenquan Wang, Xintian Zhao, Wenhui Yu, Hongyu Zheng, Xingchen Yan, Cheng Chang, Harry M. Ngwangwa, Xiaoli Cui and Zongshen Wang
Metals 2025, 15(12), 1374; https://doi.org/10.3390/met15121374 - 15 Dec 2025
Viewed by 238
Abstract
Mg alloys show great potential in biomedical fields due to superior biocompatibility and biodegradability. Additive manufacturing (AM) provides opportunities in fabricating metallic implants with complex geometries while inherent defects during AM limit its further applications. In this work, laser shock peening (LSP) was [...] Read more.
Mg alloys show great potential in biomedical fields due to superior biocompatibility and biodegradability. Additive manufacturing (AM) provides opportunities in fabricating metallic implants with complex geometries while inherent defects during AM limit its further applications. In this work, laser shock peening (LSP) was employed as a post-processing technique to tailor the surface integrity and corrosion resistance of additively manufactured AZ91 Mg alloy by selective laser melting (SLM). The surface morphology, microstructure and porosity, surface hardness and residual stress, and corrosion resistance of the SLMed alloy before and after LSP were examined. The results show that a gradient structure is formed along the depth direction after LSP and high-density dislocations and high-fraction low-angle grain boundaries are induced. The porosity is gradually reduced in number and size and the highest density of 1.794 g/cm3 is obtained after two impacts of LSP. The surface hardness and residual compressive stress both increase with LSP number and the highest values of 135.26 HV and 40.13 MPa after four impacts, respectively. All of the SLMed alloy samples show improved corrosion resistance after LSP. This work provides a promising route for enhancing the performance of additively manufactured Mg alloys through laser materials surface modification. Full article
(This article belongs to the Special Issue Laser Shock Peening: From Fundamentals to Applications)
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29 pages, 12009 KB  
Review
Anode Protection Strategies for Next-Generation Lithium–Oxygen Batteries: Toward Dendrite-Free Lithium Metal at Practical Current Densities
by Myeong-Chang Sung, Minhe Kim, Jiyoon Yu and Changhoon Choi
Metals 2025, 15(12), 1373; https://doi.org/10.3390/met15121373 - 15 Dec 2025
Viewed by 395
Abstract
The promise of lithium–oxygen batteries lie not merely in their record-breaking theoretical energy density, but in the challenge of making such energy truly reversible. Rising as the key obstacle is the lithium metal anode, whose remarkable capacity and low potential come at the [...] Read more.
The promise of lithium–oxygen batteries lie not merely in their record-breaking theoretical energy density, but in the challenge of making such energy truly reversible. Rising as the key obstacle is the lithium metal anode, whose remarkable capacity and low potential come at the cost of dendritic growth, unstable solid electrolyte interphases, and relentless reactions with oxygen species. These instabilities, once overshadowed by cathode-related limitations, now define the frontier of research as current densities and energy demands approach practical levels. This review highlights recent progress in two complementary directions for anode protection: physical approaches, such as artificial protective layers, solid or functional separators, and oxygen-blocking interlayers that isolate and stabilize the surface; and chemical strategies, including electrolyte and additive design that enable in situ formation of LiF- and Li3N-rich interfaces with high ionic conductivity and chemical robustness. Together, these approaches establish a unified framework for achieving dendrite-free and oxygen-resistant lithium interfaces. Mastering solid electrolyte interfacial stability rather than only cathode catalysis will ultimately determine whether lithium oxygen battery can evolve from laboratory prototypes to truly viable high-energy systems. Full article
(This article belongs to the Special Issue Surface Treatments and Coating of Metallic Materials)
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24 pages, 12828 KB  
Article
Surrogate-Model Prediction of Mechanical Response in Architected Ti6Al4V Cylindrical TPMS Metamaterials
by Mansoureh Rezapourian, Ali Cheloee Darabi, Mohammadreza Khoshbin, Siegfried Schmauder and Irina Hussainova
Metals 2025, 15(12), 1372; https://doi.org/10.3390/met15121372 - 15 Dec 2025
Viewed by 354
Abstract
A Machine Learning (ML)-based surrogate modeling framework is presented for mapping structure–property relationships in architected Ti6Al4V cylindrical TPMS metamaterials subjected to quasi-static compression. A Python–nTop pipeline automatically generated 3456 cylindrical shell lattices (Gyroid, Diamond, Split-P), and ABAQUS/Explicit simulations with a Johnson–Cook failure model [...] Read more.
A Machine Learning (ML)-based surrogate modeling framework is presented for mapping structure–property relationships in architected Ti6Al4V cylindrical TPMS metamaterials subjected to quasi-static compression. A Python–nTop pipeline automatically generated 3456 cylindrical shell lattices (Gyroid, Diamond, Split-P), and ABAQUS/Explicit simulations with a Johnson–Cook failure model for Ti6Al4V quantified their mechanical response. From 3024 valid designs, key mechanical properties targets including elastic modulus (E), yield stress (Y), ultimate strength (U), plateau stress (PL), and energy absorption (EA) were extracted alongside geometric descriptors such as surface area (SA), surface-area-to-volume ratio (SA/VR), and relative density (RD). A multi-output surrogate model (feedforward neural network) trained on the simulated set accurately predicts these properties directly from seven design parameters (thickness; unit cell counts in X, Y, and Z directions; unit cell orientation; height; diameter), enabling rapid property estimation across large design spaces. Topology-dependent trends indicate that Split-P exhibits the highest strength, energy absorption, and total SA, and shows the largest variation in SA/VR; Gyroid exhibits the lowest SA with a moderate SA/VR; and Diamond is the most compliant lattice and maintains a higher SA/VR than Gyroid despite lower SA. RD increases with both SA and SA/VR across all topologies. The framework provides a reusable computational tool for architectured lattices, enabling quick prescreening of implant designs without repeated finite-element analyses. Full article
(This article belongs to the Special Issue Application of Machine Learning in Metallic Materials)
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24 pages, 4862 KB  
Article
Computational Modeling of the Temperature Distribution in a Butt Weld of AISI 304L Stainless Steel Using a Volumetric Heat Source
by Thiago da Silva Machado, Thiago da Silveira, Liércio André Isoldi and Luiz Antônio Bragança da Cunda
Metals 2025, 15(12), 1371; https://doi.org/10.3390/met15121371 - 14 Dec 2025
Viewed by 359
Abstract
The Finite Element Method is an indispensable tool for analyzing the transient thermal phenomena in welding processes. This study aims to simulate the temperature field during Gas Metal Arc Welding of an AISI 304L V-groove butt joint, employing a volumetric heat source model. [...] Read more.
The Finite Element Method is an indispensable tool for analyzing the transient thermal phenomena in welding processes. This study aims to simulate the temperature field during Gas Metal Arc Welding of an AISI 304L V-groove butt joint, employing a volumetric heat source model. The numerical simulations were conducted using ABAQUS SIMULIA® (version 6.11-3) on a plate measuring 200 mm × 50 mm × 9.5 mm. For validation, the numerical results were compared against experimental data obtained at the Welding Engineering Research Laboratory of Federal University of Rio Grande. A parametric study was performed by varying the geometric parameter b (controlling the volumetric heat distribution depth) to enhance the model’s accuracy and achieve the closest approximation to experimental observations. The calibrated volumetric source demonstrated high accuracy, yielding low percentage differences between predicted and experimental peak temperatures: 1.02%, 2.50%, and 4.44% at the 4 mm, 8 mm, and 12 mm thermocouple positions, respectively. Full article
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16 pages, 5512 KB  
Article
Evaluation of Sintered Powder Metallurgy Fe-Cr Alloys as Metallic Interconnects for Solid Oxide Fuel Cell Applications
by Chien-Kuo Liu and Wei-Ja Shong
Metals 2025, 15(12), 1370; https://doi.org/10.3390/met15121370 - 12 Dec 2025
Viewed by 341
Abstract
Metallic interconnects are key components in planar solid oxide fuel cell (SOFC) stacks. In the present study, we evaluated four Fe-Cr powder metallurgy (PM) alloy specimens, obtained from a domestic manufacturer, at nominal compositions (in wt%) of 5% Fe-95% Cr, 30% Fe-70% Cr, [...] Read more.
Metallic interconnects are key components in planar solid oxide fuel cell (SOFC) stacks. In the present study, we evaluated four Fe-Cr powder metallurgy (PM) alloy specimens, obtained from a domestic manufacturer, at nominal compositions (in wt%) of 5% Fe-95% Cr, 30% Fe-70% Cr, 50% Fe-50% Cr, and 78% Fe-22% Cr. These specimens were tested and evaluated for use in SOFC stack applications. The verification items included coefficient of thermal expansion measurements, high-temperature oxidation resistance and weight gain tests, mechanical strength tests, high-temperature sealant bonding and leakage rate measurements, and high-temperature electrical property (i.e., area-specific resistance) measurements. In addition, the specimens’ microstructures and elemental compositions were observed and analyzed. The test results indicate that the Fe content of the Fe-Cr powder metallurgy alloys influences various properties, while Cr also plays a significant role in high-temperature oxidation resistance. Among the four alloy specimens, the 78Fe-Cr alloy exhibited all of the aforementioned advantages, including a suitable coefficient of thermal expansion of 12.4 × 10−6/°C, excellent high-temperature oxidation resistance, a thermal weight-gain rate of 5.31 × 10−14 g2/cm4·s, a remarkably low high-temperature area-specific resistance of 7.04 mΩ·cm2, and superior bonding and interfacial stability with the GC9 glass–ceramic sealant, achieving a very low leakage rate of 3.47 × 10−6 mbar·l/s/cm. These results indicate that the 78Fe-Cr powder metallurgy alloy performs excellently and is the most promising candidate for metallic interconnects in SOFC stack applications. Full article
(This article belongs to the Section Metallic Functional Materials)
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18 pages, 10785 KB  
Article
Microstructure, Texture, and Mechanical Properties of 6N Ultra-High-Purity Copper Processed by Cryorolling for Advanced Sputtering Targets
by Wenpeng Yuan, Shifeng Liu, Hang Zhao, Linyu Lu, Qiuyan Xie and Xinggui Lei
Metals 2025, 15(12), 1369; https://doi.org/10.3390/met15121369 - 12 Dec 2025
Viewed by 289
Abstract
The performance of ultra-high-purity copper sputtering targets is critical for nanoscale integrated circuit fabrication, yet challenges such as dynamic recovery and recrystallization hinder grain refinement and texture control. In the present work, cryogenic deformation was introduced to address these issues. Through electron backscatter [...] Read more.
The performance of ultra-high-purity copper sputtering targets is critical for nanoscale integrated circuit fabrication, yet challenges such as dynamic recovery and recrystallization hinder grain refinement and texture control. In the present work, cryogenic deformation was introduced to address these issues. Through electron backscatter diffraction (EBSD), X-ray diffraction (XRD), and mechanical testing, the microstructure, texture, and mechanical properties of 6N ultra-high-purity copper processed by room-temperature rolling (RTR) and cryorolling (CR) were comparatively investigated. Results reveal that RTR deformation is dominated by slip mechanisms; the RTR sample with 90% reduction exhibits obvious dynamic recrystallization (DRX) and forms a bimodal structure dominated by Copper ({112}⟨111⟩) and S ({123}⟨634⟩) textures. In contrast, CR suppresses thermal activation processes, enabling deformation mechanisms suggestive of twinning activity, leading to ultrafine fibrous structures, while shifting texture components toward Brass ({110}⟨112⟩) and S. Compared to RTR-processed samples, CR-processed samples possess superior mechanical performance. The CR sample with 90% reduction exhibits: a microhardness of 164.60 HV, a yield strength of 385.61 MPa, and a tensile strength of 648.02 MPa, which are, respectively, 33.2%, 91.7%, and 84.6% higher than those of RTR counterparts. Williamson–Hall analysis confirms that the CR sample with 90% reduction achieves finer substructure sizes (~133 nm) and higher stored energy (~22 J·mol−1) by suppressing dynamic recovery, providing a robust driving force for subsequent annealing. This work demonstrates that cryorolling optimizes microstructure and texture through twin-dislocation synergy, providing a fundamental basis for the development of advanced sputtering targets. Full article
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11 pages, 1992 KB  
Article
Metastable Ferromagnetic B2 Phase in AlCr Alloy Through Co Addition
by Esmat Dastanpour, Haireguli Aihemaiti, Valter Ström and Levente Vitos
Metals 2025, 15(12), 1368; https://doi.org/10.3390/met15121368 - 12 Dec 2025
Viewed by 246
Abstract
Recently, we reported an antiferromagnetic ground state for equiatomic Al-Cr in the B2 structure. Here, by a joint theoretical–experimental study, we investigate the effect of Co additions to the Al-Cr alloy with the aim to synthesize a ferromagnetic B2 phase. Al50Cr [...] Read more.
Recently, we reported an antiferromagnetic ground state for equiatomic Al-Cr in the B2 structure. Here, by a joint theoretical–experimental study, we investigate the effect of Co additions to the Al-Cr alloy with the aim to synthesize a ferromagnetic B2 phase. Al50Cr38Co12 (at.%) is prepared by arc melting from high-purity raw materials and solidifies into a combination of a Co-enriched B2 phase, a Co-depleted BCC phase, and an Al8Cr5 intermetallic phase. The as-cast alloy is ferromagnetic with a Curie point of 260 K, primarily due to the presence of about 54% B2 phase. Subsequent annealing decreases the fraction of the B2 phase to 27% with depletion of Cr from 20.2 at.% to 16.1 at.%, which leads to a reduction in its ferromagnetic behavior. Calculations based on Density Functional Theory (DFT) predict a corresponding decrease in the total magnetic moment and Curie temperature of the B2 phase by annealing. The present findings highlight the roles of Cr and Co in facilitating the formation of a metastable ferromagnetic B2 phase in this alloy. Full article
(This article belongs to the Special Issue Metallic Magnetic Materials: Manufacture, Properties and Applications)
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15 pages, 1727 KB  
Article
Superconductivity in the Intercalated Graphite Compound CaC6 and the Roeser–Huber Formalism
by Michael R. Koblischka and Anjela Koblischka-Veneva
Metals 2025, 15(12), 1367; https://doi.org/10.3390/met15121367 - 11 Dec 2025
Viewed by 352
Abstract
The superconducting transition temperature, Tc, of the graphite intercalation compound, CaC6, was calculated using the Roeser–Huber (RH) formalism. This method was adapted to alloys with complex crystal structures by identifying symmetric paths for the superconducting charge carriers (Cooper [...] Read more.
The superconducting transition temperature, Tc, of the graphite intercalation compound, CaC6, was calculated using the Roeser–Huber (RH) formalism. This method was adapted to alloys with complex crystal structures by identifying symmetric paths for the superconducting charge carriers (Cooper pairs) and incorporating interactions with neighboring atoms through phonon coupling. The evaluation of the lowest energy levels, Δ(0), along all relevant crystallographic directions reveals a slight anisotropy between the in-plane and out-of-plane directions, consistent with the experimental observation of the gap anisotropy by point contact spectroscopy. The Tc values obtained for CaC6, CaC6 with applied high pressure, and YbC6 show good agreement with experimental data, thereby supporting both the validity of the RH approach and its predictive capability in describing superconductivity within complex crystal structures. Full article
(This article belongs to the Section Metallic Functional Materials)
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7 pages, 190 KB  
Editorial
Environmentally Assisted Degradation of Metals and Alloys
by Shidong Wang
Metals 2025, 15(12), 1366; https://doi.org/10.3390/met15121366 - 11 Dec 2025
Viewed by 278
Abstract
Metallic materials play a central role in ensuring the safety and reliability of critical sectors such as infrastructure, energy, and transportation [...] Full article
(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)
27 pages, 13345 KB  
Article
Micro and Macrostructural Assessment of Welded 6082 Aluminium Alloy T-Connections
by Darko Landek, Ivica Garašić, Davor Skejić, Anđelo Valčić, Ivan Čudina and Mislav Štefok
Metals 2025, 15(12), 1365; https://doi.org/10.3390/met15121365 - 11 Dec 2025
Viewed by 373
Abstract
One of the main challenges in welding aluminium concerns structural integrity and a significant reduction in mechanical properties in the region adjacent to the weld. Design provisions can result in a drastic reduction, which may exceed 50% of the base metal resistance. This [...] Read more.
One of the main challenges in welding aluminium concerns structural integrity and a significant reduction in mechanical properties in the region adjacent to the weld. Design provisions can result in a drastic reduction, which may exceed 50% of the base metal resistance. This research aims to evaluate the accuracy of the HAZ extent values codified in Eurocode 9 for T-connections fabricated from artificially aged 6082 aluminium alloy, which is widely used in load-bearing structures. Three plate thicknesses (6, 8 and 10 mm) and two pulsed MIG welding processes (DC-MIG-P and AC-MIG-P) were used to fabricate 20 T-connection specimens (10 different configurations) in accordance with EN 1090-3. The study focuses on characterising the welding zones through hardness testing and metallographic examination. Results show that AC-MIG-P offers better control over thermal input and may reduce structural distortion, while DC-MIG-P provides more robust fusion and metallurgical continuity. Findings related to HAZ extent (12.77 mm and 15.36 mm maximum measured for AC-MIG-P and DC-MIG-P, respectively) suggest that Eurocode 9 may be overly conservative for pulsed MIG welding processes, particularly for greater plate thicknesses where a HAZ extent of 22.50 mm or more is specified. Consequently, adopting more precise, process-specific HAZ characterisations could lead to more realistic connection design and structural behaviour. Full article
(This article belongs to the Special Issue Novel Insights into Welding and Joining Technologies of Metallic Materials)
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17 pages, 10396 KB  
Article
Laser Powder Bed-Fused Scalmalloy®: Effect of Long Thermal Aging on Hardness and Electrical Conductivity
by Emanuele Ghio, Lorenzo Curti, Daniele Carosi, Alessandro Morri and Emanuela Cerri
Metals 2025, 15(12), 1364; https://doi.org/10.3390/met15121364 - 11 Dec 2025
Viewed by 334
Abstract
This study investigates the microstructural evolution, porosity characteristics, and mechanical behavior of LPBF-manufactured Scalmalloy®, which were investigated in the as-built conditions and after long-term exposure to direct aging of 275, 325, and 400 °C. Optical microscopy, and electron backscatter diffraction (EBSD) [...] Read more.
This study investigates the microstructural evolution, porosity characteristics, and mechanical behavior of LPBF-manufactured Scalmalloy®, which were investigated in the as-built conditions and after long-term exposure to direct aging of 275, 325, and 400 °C. Optical microscopy, and electron backscatter diffraction (EBSD) analyses were employed to examine the grain morphology, pore distribution, and defect characteristics. In the as-built state, the microstructure displayed the typical fish-scale melt pool morphology with columnar grains in the melt pool centers and fine equiaxed grains along their boundaries, combined with a small number of gas pores and lack-of-fusion defects. After direct aging, coarsening of grains was revealed, accompanied by partial spheroidization of pores, though the global density remained above 99.7%, ensuring structural integrity. Grain orientation analyses revealed a reduction in crystallographic texture and local misorientation after direct aging, suggesting stress relaxation and a more homogeneous microstructure. The hardness distribution reflected this transition: in the as-built state, higher hardness values were found at melt pool edges, while coarser central grains exhibited lower hardness. After direct aging, the hardness differences between these regions decreased, and the average hardness increased from (104 ± 7) HV0.025 to (170 ± 10) HV0.025 due to precipitation of Al3(Sc,Zr) phases. Long-term aging studies confirmed the stability of mechanical performance at 325 °C, whereas aging at 400 °C induced overaging and hardness loss due to precipitate coarsening. Electrical conductivities increased monotonically at all tested temperatures from ~11.7 MS/m, highlighting the interplay between solute depletion and precipitate evolution. Full article
(This article belongs to the Special Issue Recent Advances in Powder-Based Additive Manufacturing of Metals)
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15 pages, 2803 KB  
Article
Analysis of the Regulatory Effect of Semi-Solid Isothermal Treatment Time on Crystallization and Plasticity of Amorphous Composites
by Xinhua Huang, Guang Wang, Bin Chen, Chenghao Wei, Jintao Zhao, Longguang Wu, Qi Li and Yuejun Ouyang
Metals 2025, 15(12), 1363; https://doi.org/10.3390/met15121363 - 11 Dec 2025
Viewed by 209
Abstract
Ti48Zr27Cu6Nb5Be14 amorphous composites were prepared by copper mold suction casting to obtain as-cast specimens. Subsequently, the as-cast specimens were held at 900 °C for different durations (5, 10, 20, 30, and 40 min) and [...] Read more.
Ti48Zr27Cu6Nb5Be14 amorphous composites were prepared by copper mold suction casting to obtain as-cast specimens. Subsequently, the as-cast specimens were held at 900 °C for different durations (5, 10, 20, 30, and 40 min) and then water quenched to cool, yielding treated specimens. Room-temperature compression tests were conducted to characterize the mechanical properties of the materials before and after the treatment. X-ray diffraction (XRD), optical microscopy (OM), and scanning electron microscopy (SEM) were used to detect and observe the microstructure of the specimens (before and after treatment) as well as the morphology of the side surface of compressed fractured specimens. Results show that the as-cast specimens are amorphous matrix composites, with dendrites (identified as β-Ti) predominantly distributed in the amorphous matrix. When the treatment duration increased from 5 to 40 min, two key phenomena were observed. The dendrites gradually disappeared and evolved into curved crystals first; subsequently, the curved crystals transformed into elongated crystals. Finally, the elongated crystals evolved into short and thick rod-like crystals, which further transformed into near-spherical crystals or spherical crystals. Furthermore, as the treatment duration prolonged, the average equivalent size of the crystals increased continuously, reaching 23.1 μm. Additionally, the plasticity of the specimens first increased, reached a maximum value of 16.2% when held for 30 min, and then decreased. Full article
(This article belongs to the Special Issue Research Progress of Crystal in Metallic Materials)
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15 pages, 6689 KB  
Article
Study of Selective Recovery of Lead- and Zinc-Based Products from Leachate After Alkaline Leaching of Copper Shaft Furnace Dust
by Michaela Ružičková, Martina Laubertová and Michal Marcin
Metals 2025, 15(12), 1362; https://doi.org/10.3390/met15121362 - 11 Dec 2025
Viewed by 260
Abstract
A leachate from alkaline leaching of copper shaft furnace (CSF) dust as a hazardous waste was used in this study for performing a chemical precipitation experiment of lead, zinc, and copper. The precipitation processes for lead, zinc, and copper were theoretically optimized based [...] Read more.
A leachate from alkaline leaching of copper shaft furnace (CSF) dust as a hazardous waste was used in this study for performing a chemical precipitation experiment of lead, zinc, and copper. The precipitation processes for lead, zinc, and copper were theoretically optimized based on a thermodynamic study. To determine suitable operating conditions, metal phase stability, reaction mechanisms, and precipitation order were analyzed using the Hydra/Medusa and HSC Chemistry v.10 software packages. In the first experimental stage, treatment of the alkaline leachate resulted in the formation of insoluble lead sulfate (PbSO4), while zinc remained dissolved for subsequent recovery. In the second stage, the zinc-bearing solution was treated with Na2CO3, producing a mixed zinc precipitate consisting of Zn5(OH)6(CO3)2(s). This study determined that the optimal conditions for chemically precipitating lead as PbSO4 from alkaline leachate (pH 13.5) are the use of 1 mol/L H2SO4 at pH 3.09 and Eh 0.22 V at 25 °C, while optimal zinc precipitation from this solution (pH 3.02) is achieved with 2 mol/L Na2CO3 at pH 9.39 and Eh –0.14 V at 25 °C. A small amount of copper present in the solution co-precipitated and was identified as an impurity in the zinc product. The chemical composition of the resulting precipitates was confirmed by SEM–EDX analysis. Full article
(This article belongs to the Special Issue Studies on Metal Leaching, Extraction and Recovery)
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25 pages, 31603 KB  
Article
Effect of Quenching and Partitioning on Microstructure, Impact Toughness and Wear Resistance of a Gray Cast Iron
by Edson Luiz da Silva Junior, Fábio Edson Mariani, Selauco Vurobi Junior, Camila Yuri Negrão Konno, Adriano Corrêa Batista, Tiago Manoel de Oliveira Santos, Mariana Botelho Barbosa and Kahl Dick Zilnyk
Metals 2025, 15(12), 1361; https://doi.org/10.3390/met15121361 - 10 Dec 2025
Viewed by 283
Abstract
This study investigates the influence of quenching and partitioning (Q&P) on the microstructure, hardness, wear resistance, and impact toughness of GG25 gray cast iron, in comparison with as-cast, quenched, quenched-and-tempered, and austempered conditions. Q&P treatment promotes a significant fraction of retained austenite, with [...] Read more.
This study investigates the influence of quenching and partitioning (Q&P) on the microstructure, hardness, wear resistance, and impact toughness of GG25 gray cast iron, in comparison with as-cast, quenched, quenched-and-tempered, and austempered conditions. Q&P treatment promotes a significant fraction of retained austenite, with carbon enrichment stabilizing the austenite at room temperature. Microstructural analysis reveals a multiphase matrix composed of partitioned martensite, bainitic ferrite and carbon-enriched retained austenite, while the morphology and distribution of graphite flakes remain unchanged. Mechanical testing shows that Q&P enhances impact toughness without substantial loss of hardness, achieving a balance not observed in conventional quenching and tempering treatments. Tribological evaluation indicates that wear resistance is slightly lower than quenched and tempered samples but superior to as-cast iron, with deformation of retained austenite and tribofilm formation influencing wear behavior. These results demonstrate that Q&P represents a promising route for developing gray cast irons with enhanced toughness and maintained hardness, suitable for components subjected to impact and wear loading. Full article
(This article belongs to the Special Issue Mechanical and Structural Properties of Cast Irons)
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