Journal Description
Metals
Metals
is an international, peer-reviewed, open access journal published monthly online by MDPI. The Portuguese Society of Materials (SPM), and the Spanish Materials Society (SOCIEMAT) are affiliated with Metals and their members receive a discount on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, CAPlus / SciFinder, and other databases.
- Journal Rank: JCR - Q2 (Metallurgy & Metallurgical Engineering) / CiteScore - Q1 (Metals and Alloys)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 15 days after submission; acceptance to publication is undertaken in 2.7 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Companion journals for Metals include: Compounds and Alloys.
Impact Factor:
2.9 (2022);
5-Year Impact Factor:
2.9 (2022)
Latest Articles
A Metal Accelerator Approach for Discharging Cylindrical Lithium-Ion Batteries in a Salt Solution
Metals 2024, 14(6), 657; https://doi.org/10.3390/met14060657 (registering DOI) - 31 May 2024
Abstract
Recycling lithium-ion batteries provides sustainable raw materials. Crushing and separation are necessary for extracting metals, like lithium, from batteries. Crushing a battery carries a risk of fire or explosion. Fully discharging the battery is crucial for safe production. Discharging batteries in a salt
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Recycling lithium-ion batteries provides sustainable raw materials. Crushing and separation are necessary for extracting metals, like lithium, from batteries. Crushing a battery carries a risk of fire or explosion. Fully discharging the battery is crucial for safe production. Discharging batteries in a salt solution is a simple and cost-effective large-scale process. However, it is important to note that there is a potential risk of corrosion and loss of battery elements when batteries are immersed in a salt solution. The purpose of this study is to investigate the effectiveness of two distinct methodologies at enhancing the voltage drop of a cylindrical battery when immersed in a salt solution while preventing corrosion. These techniques involve the application of iron and copper accelerators. A 20 wt.% salt water solution was chosen based on the research of several researchers. As the current flows through the metal parts, it encounters electrical resistance and forms an electric circuit with the electrolyte solution. This interaction converts electrical energy into various physical–electrical–electrochemical phenomena, leading to a decrease in battery voltage. Research revealed that the battery can be discharged up to 100% within 4 h without causing corrosion to its components. Another point to note is that if copper conductors are used, it is possible to decrease the battery voltage by around 90% within 8 h. The gap between the copper conductor and the battery had a direct impact on the battery’s discharge rate. Reducing the distance significantly increased the discharge rate, as confirmed by experimental evidence. This discharge mechanism was thoroughly described in a schematic, and, to further explain the electrochemical reaction, the Pourbaix diagram was utilized for both the Fe-Na-Cl and Cu-Na-Cl systems. Moreover, our theoretical predictions were validated through a chemical and mineralogical analysis of the precipitates that formed in the solution.
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(This article belongs to the Special Issue Recovery and Utilization of Metallurgical Solid Wastes)
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Local Buckling of Locally Sharp-Notched C2700 Brass Circular Tubes Subjected to Cyclic Bending
by
Yu-An Chen and Wen-Fung Pan
Metals 2024, 14(6), 656; https://doi.org/10.3390/met14060656 - 31 May 2024
Abstract
This paper aims to investigate the response and local buckling of locally sharp-notched C2700 brass circular tubes (LSN C2700 brass circular tubes) under cyclic bending loads. The study considers four different notch orientations (0°, 30°, 60°, and 90°) and five distinct notch depths
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This paper aims to investigate the response and local buckling of locally sharp-notched C2700 brass circular tubes (LSN C2700 brass circular tubes) under cyclic bending loads. The study considers four different notch orientations (0°, 30°, 60°, and 90°) and five distinct notch depths (0.2, 0.4, 0.6, 0.8, and 1.0 mm). The results reveal that notch orientation and depth exert minimal impact on the moment–curvature relationship, leading to the formation of stable loops. The ovalization–curvature graphs demonstrate a trend of symmetry, serration, and growth with an increasing number of bending cycles. Additionally, larger notch orientations or smaller notch depths result in reduced ovalization. Furthermore, the double logarithmic coordinates of controlled curvature–number of cycles necessary to induce local buckling reveal five non-parallel lines representing different notch depths when the notch orientation is fixed. Finally, by adopting the formulas for smooth tubes and for locally sharp-notched 304 stainless steel circular tubes (LSN SS304 circular tubes), this study adjusts the related material parameters accordingly. These modifications effectively describe the controlled curvature–number of cycles necessary to induce local buckling for LSN C2700 brass circular tubes with different notch orientations and depths under cyclic bending, demonstrating reasonable agreement with the experimental results.
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(This article belongs to the Special Issue Failure and Degradation of Metals)
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Open AccessArticle
Effect of Nd on Functional Properties of Biodegradable Zn Implants in In Vitro Environment
by
Efrat Hazan-Paikin, Lital Ben Tzion-Mottye, Maxim Bassis, Tomer Ron and Eli Aghion
Metals 2024, 14(6), 655; https://doi.org/10.3390/met14060655 - 31 May 2024
Abstract
The present study aims to evaluate the effect of up to 3 wt.% Nd on pure Zn in terms of physical properties and in vitro analysis. The use of Nd as an alloying element is due to its relatively adequate biocompatibility and its
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The present study aims to evaluate the effect of up to 3 wt.% Nd on pure Zn in terms of physical properties and in vitro analysis. The use of Nd as an alloying element is due to its relatively adequate biocompatibility and its potential capability to reinforce metals with a hexagonal close-packed (HCP) crystal structure, such as Mg and Zn. The microstructural assessment was executed using X-ray diffraction analysis, along with optical and scanning electron microscopy. The mechanical properties were evaluated by hardness and tensile strength testing. The corrosion performance in simulated physiological environments was examined by means of immersion tests, potentiodynamic polarization, and impedance spectroscopy using phosphate-buffered saline (PBS) solution. Cytotoxicity assessment was carried out by indirect cell viability analysis according to the ISO 10993-5/12 standard using Mus musculus 4T1 cells, which are known to be very sensitive to toxic environments. The obtained results clearly highlighted the reinforcing effect of Nd in Zn-base alloys, mainly due to the formation of a secondary phase: NdZn5. This strengthening effect was acquired without impairing the inherent ductility and corrosion performance of the tested alloys. The cytotoxicity assessment indicated that the addition of Nd has a strong favorable effect on cell viability, which stimulates the inherent anti-inflammatory characteristics of Zn.
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(This article belongs to the Section Biobased and Biodegradable Metals)
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The Formation Mechanism of Oxide Inclusions in a High-Aluminum Ni-Based Superalloy during the Vacuum Induction Remelting Process
by
Lihui Zhang, Erkang Liu, Weijie Xing, Zhaojiang Xue, Wenjie Fan, Yunsong Zhao, Yushi Luo, Changchun Ge and Min Xia
Metals 2024, 14(6), 654; https://doi.org/10.3390/met14060654 - 30 May 2024
Abstract
Oxide inclusions in Ni-based superalloys play a crucial role in determining their mechanical properties, oxidation resistance, and corrosion resistance at high temperatures. In this paper, the source and formation mechanism of different types of oxide inclusions in a high-aluminum Ni-based superalloy were systematically
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Oxide inclusions in Ni-based superalloys play a crucial role in determining their mechanical properties, oxidation resistance, and corrosion resistance at high temperatures. In this paper, the source and formation mechanism of different types of oxide inclusions in a high-aluminum Ni-based superalloy were systematically studied. An automatic field emission scanning electron microscope equipped with an energy dispersive spectrometer and a self-designed superalloy inclusion analysis standard was utilized to quantitatively reveal the oxide inclusion characteristics of the high-aluminum Ni-based superalloy prepared via vacuum induction melting (VIM) and vacuum induction remelting (VIR) processes. The experimental results indicate that the typical oxide inclusions in the Ni-based superalloy before the VIR process are irregular MgO·Al2O3 inclusions with sizes of less than 2 μm. After the VIR process, the typical oxide inclusions in the Ni-based superalloy are also MgO·Al2O3 inclusions. However, these oxide inclusions can be classified into three categories: (i) endogenous irregular MgO·Al2O3 inclusions, less than 4.3 μm in size, inherited from the master alloy; (ii) several hundred-micron film-like MgO·Al2O3 inclusions generated as interface reaction products between the MgO crucible and melts; and (iii) millimeter-scale MgO·Al2O3 inclusions and several tens of microns of MgO inclusions from the exfoliation of the MgO crucible matrix.
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(This article belongs to the Special Issue Solidification and Casting of Metals and Alloys)
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Open AccessArticle
Comparative Analysis of Three Different Probe Designs for Reducing Hook Defects in FSW of AA6005-T6 Aluminum Alloy
by
Liuyang Qin, Hongxia Zhang, Gongbo Bian, Kewei Li and Peng Dong
Metals 2024, 14(6), 653; https://doi.org/10.3390/met14060653 - 30 May 2024
Abstract
Hook defects are common in FSW butt–lap joints, resulting in a significant safety hazard for the parts that suffer cyclic load. In this study, a numerical simulation based on the Euler–Lagrange coupling method was conducted to investigate the formation process of hook defect
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Hook defects are common in FSW butt–lap joints, resulting in a significant safety hazard for the parts that suffer cyclic load. In this study, a numerical simulation based on the Euler–Lagrange coupling method was conducted to investigate the formation process of hook defect during FSW of AA6005-T6 aluminum alloy. The simulation results were validated with experimental data, showing good agreement. The formation of the hook defect is caused by the threads on the probe promoting material flow in the thickness direction. In order to further study the effect of probe morphology on hook defects, three kinds of probe models with different morphology were established and numerically simulated by the CEL method. The simulation results show that all three kinds of probes can reduce the size of the hook. The welds obtained using the left–left probe (LLP) and the three-plane probe (TPP) both exhibit void defects, while the welds obtained by a right–left probe (RLP) have no internal void defects. The experimental results show the same characteristics as the simulation results, and the size of the hook defect is reduced to 58 μm.
Full article
(This article belongs to the Special Issue Recent Trends in Friction Stir-Related Manufacturing Technologies)
Open AccessArticle
A Study on the Influence of Different Defect Types on the Corrosion Behavior of Q235/TA2 Composite Plates in a Marine Environment
by
Jianbo Jiang, Nannan Li, Bingqin Wang, Fangfang Liu, Chao Liu and Xuequn Cheng
Metals 2024, 14(6), 652; https://doi.org/10.3390/met14060652 - 30 May 2024
Abstract
The structural design of steel–titanium composite plates significantly affects their corrosion resistance. To investigate the impact of defects of different shapes and sizes on the corrosion behavior of steel–titanium composite plates, this study designed six types of defects and conducted a series of
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The structural design of steel–titanium composite plates significantly affects their corrosion resistance. To investigate the impact of defects of different shapes and sizes on the corrosion behavior of steel–titanium composite plates, this study designed six types of defects and conducted a series of characterization tests. The results showed that due to the galvanic interaction between carbon steel and titanium alloy, small defects initially accelerate corrosion, resulting in 50% to 200% more corrosion weight loss compared to large defects. However, in the later stages of immersion, the corrosion rate of small defects decreased by up to 35%, which was attributed to the accumulation of protective corrosion products. Additionally, there is an inverse relationship between the corrosion rate and the thickness ratio of the composite plate. The reduction in the area of Q345B also results in additional corrosion loss of up to 32%.
Full article
(This article belongs to the Special Issue Advances in Corrosion and Protection of Materials (Second Edition))
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Open AccessArticle
The Influence of the Structural Parameters of Nanoporous Alumina Matrices on Optical Properties
by
Ekaterina N. Muratova, Alina A. Ponomareva, Andrey A. Shemukhin, Yuriy V. Balakshin, Aleksandr P. Evseev, Vyacheslav A. Moshnikov, Anton A. Zhilenkov and Olga Yu. Kichigina
Metals 2024, 14(6), 651; https://doi.org/10.3390/met14060651 - 30 May 2024
Abstract
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In this work, two types of nanoporous alumina membranes were prepared and tested. Structural features of the samples obtained by using different acids were investigated by scanning electron microscopy (SEM). And further SEM-images were analyzed by different types of fractal dimension estimation methods.
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In this work, two types of nanoporous alumina membranes were prepared and tested. Structural features of the samples obtained by using different acids were investigated by scanning electron microscopy (SEM). And further SEM-images were analyzed by different types of fractal dimension estimation methods. The transmission and scattering of accelerated He+ ions were studied in experiments on the ion irradiation of dielectric channels based on porous alumina. An ion accelerator was used as a source of the He+ beam with an energy of 1.7 MeV. Ion scattering was studied by Rutherford backscattering spectrometry. Helium transition through nanoporous alumina at various angles between the normal to the sample and the beam direction were observed. It is shown that the porous structure of anodic aluminum oxide is excellent as a dielectric matrix of nanocapillaries. Owing to the small angle scattering, it allows for the transportation of the accelerated charged particles through the dielectric capillaries, and, as a result, the localization of high energy ion irradiation effects. Additionally, according to the transmission of UV–V is spectra, the energy gaps of samples obtained were calculated.
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Open AccessArticle
SDD-YOLO: A Lightweight, High-Generalization Methodology for Real-Time Detection of Strip Surface Defects
by
Yueyang Wu, Ruihan Chen, Zhi Li, Minhua Ye and Ming Dai
Metals 2024, 14(6), 650; https://doi.org/10.3390/met14060650 - 30 May 2024
Abstract
Flat-rolled steel sheets are one of the major products of the metal industry. Strip steel’s production quality is crucial for the economic and safety aspects of humanity. Addressing the challenges of identifying the surface defects of strip steel in real production environments and
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Flat-rolled steel sheets are one of the major products of the metal industry. Strip steel’s production quality is crucial for the economic and safety aspects of humanity. Addressing the challenges of identifying the surface defects of strip steel in real production environments and low detection efficiency, this study presents an approach for strip defect detection based on YOLOv5s, termed SDD-YOLO. Initially, this study designs the Convolution-GhostNet Hybrid module (CGH) and Multi-Convolution Feature Fusion block (MCFF), effectively reducing computational complexity and enhancing feature extraction efficiency. Subsequently, CARAFE is employed to replace bilinear interpolation upsampling to improve image feature utilization; finally, the Bidirectional Feature Pyramid Network (BiFPN) is introduced to enhance the model’s adaptability to targets of different scales. Experimental results demonstrate that, compared to the baseline YOLOv5s, this method achieves a 6.3% increase in mAP50, reaching 76.1% on the Northeastern University Surface Defect Database for Detection (NEU-DET), with parameters and FLOPs of only 3.4MB and 6.4G, respectively, and FPS reaching 121, effectively identifying six types of defects such as Crazing and Inclusion. Furthermore, under the conditions of strong exposure, insufficient brightness, and the addition of Gaussian noise, the model’s mAP50 still exceeds 70%, demonstrating the model’s strong robustness. In conclusion, the proposed SDD-YOLO in this study features high accuracy, efficiency, and lightweight characteristics, making it applicable in actual production to enhance strip steel production quality and efficiency.
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(This article belongs to the Special Issue Machine Learning Models in Metals)
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Importance of Changes in the Copper Production Process through Mining and Metallurgical Activities on the Surface Water Quality in the Bor Area, Serbia
by
Radmila Marković, Vesna M. Marjanović, Zoran Stevanović, Vojka Gardić, Jelena Petrović, Renata Kovačević, Zoran Štirbanović and Bernd Friedrich
Metals 2024, 14(6), 649; https://doi.org/10.3390/met14060649 - 29 May 2024
Abstract
This paper considers the impact of copper mining-influenced water and metallurgical wastewater on the surface water in the Bor area, Serbia. Sampling, realized through the four campaigns (2020–2021), confirmed that both types of water, discharged without appropriate treatment in the Bor River, had
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This paper considers the impact of copper mining-influenced water and metallurgical wastewater on the surface water in the Bor area, Serbia. Sampling, realized through the four campaigns (2020–2021), confirmed that both types of water, discharged without appropriate treatment in the Bor River, had a signific impact on the concentration of metal ions, pH and electrical conductivity on the watercourse in the Bor area. The highest concentrations of the following metal ions, Cu-271 mg/L, As-25991 μg/L, Ni-13856 μg/L, Cd-2627 μg/L, and Pb-2855 μg/L, were registered in the metallurgical wastewater samples. After changes occurred in the copper production process by stopping the discharge of untreated wastewater into the Bor River, the concentrations of monitored elements were drastically decreased. In the period 2022–2024, the concentration values for Cu, As and Pb ions were below the maximum allowable value, and the concentration values of Ni and Cd ions were also decreased. The values for pH and electrical conductivity were in the maximum allowable range. The return of wastewater to the copper production process would lead to both a reduction in the primary water consumption and reduction in the negative impact on the environment.
Full article
(This article belongs to the Special Issue Feature Papers in Extractive Metallurgy)
Open AccessArticle
Effect of Electro-Pulse on Microstructure of Al-Cu-Mn-Zr-V Alloy during Aging Treatment and Mechanism Analysis
by
Dequan Shi, Wenbo Yu, Guili Gao and Kaijiao Kang
Metals 2024, 14(6), 648; https://doi.org/10.3390/met14060648 - 29 May 2024
Abstract
The effects of electro-pulse on microstructure and mechanical properties of Al-Cu-Mn-Zr-V alloy were investigated, and the ageing mechanism was analyzed. As the current density increases, the size and quantity of precipitates gradually transit from continuous aggregation to dispersion at grain boundaries, and the
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The effects of electro-pulse on microstructure and mechanical properties of Al-Cu-Mn-Zr-V alloy were investigated, and the ageing mechanism was analyzed. As the current density increases, the size and quantity of precipitates gradually transit from continuous aggregation to dispersion at grain boundaries, and the mechanical properties are improved. When the current density is 15 A·mm−2, the precipitates are smallest and the mechanical properties are best. The tensile strength is 443.5 MPa and the elongation is 8.1%, which are 51.7% and 42.1% higher than those of conventional ageing treatment, respectively. Once the current density exceeds 15 A·mm−2, the precipitates will increase again and gather at grain boundaries, and the mechanical properties also decrease. An additional electrical free energy arising from an electro-pulse provides thermodynamic and kinetic conditions for the ageing precipitation of second phases. The electro-pulse can enhance the ageing diffusion coefficient, being improved by 34 times for 15 A·mm−2. The electro-pulse improves the nucleation rate and decreases the critical nucleation radii of second phases. However, it also accelerates the grain growth, making the second phases become coarse. An electro-pulse with a current density of 15 A·mm−2 can rapidly nucleate the second phase at 463 K while the precipitates are relatively small after growth.
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(This article belongs to the Special Issue Numerical Simulation of Foundry and Solidification Processes)
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The Influence of Hot Deformation on the Mechanical and Structural Properties of 42CrMo4 Steel
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Mariana Pop, Ioana-Monica Sas-Boca, Dan Frunză, Florin Popa and Adriana Neag
Metals 2024, 14(6), 647; https://doi.org/10.3390/met14060647 - 29 May 2024
Abstract
The influence of elevated temperatures and strain rate on the mechanical and structural properties of steel 42CrMo4 were analysed experimentally in this paper. The experiments were based on uniaxial tension and compression tests at high temperatures between 700 °C and 1100 °C and
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The influence of elevated temperatures and strain rate on the mechanical and structural properties of steel 42CrMo4 were analysed experimentally in this paper. The experiments were based on uniaxial tension and compression tests at high temperatures between 700 °C and 1100 °C and strain rates in the range 0.0018–0.1 s−1. The influence of temperature and strain rate on yield stress, strain to fracture, hardness, structural changes, and fracture characteristics were analysed. The non-uniformity of deformations obtained at different values of the strain rate and temperature were also analysed. Analysis by scanning electron microscopy showed the ductile behaviour of the material. The degree of damage in the material caused by the presence of cavities increased with increasing deformation temperature. For all the presented deformation conditions, the formation of the fracture through the ductile fracture mechanism resulted from localized necking and the coalescence of microvoids. By increasing the deformation temperature and reducing the strain rate, the fracture behaviour of 42CrMo4 steel can be improved.
Full article
(This article belongs to the Special Issue Forging of Metals and Alloys)
Open AccessArticle
The Effect of Niobium on the Mechanical and Thermodynamic Properties of Zirconium Alloys
by
Xianggang Kong, Huimin Kuang, An Li, You Yu, Dmitrii O. Kharchenko, Jianjun Mao and Lu Wu
Metals 2024, 14(6), 646; https://doi.org/10.3390/met14060646 - 29 May 2024
Abstract
The alloy element Nb plays an important role in improving the performance of zirconium alloys in nuclear reactors. The effect mechanism of Nb doping on mechanical and thermodynamic properties was investigated using experimental and theoretical methods. The results of this study showed us
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The alloy element Nb plays an important role in improving the performance of zirconium alloys in nuclear reactors. The effect mechanism of Nb doping on mechanical and thermodynamic properties was investigated using experimental and theoretical methods. The results of this study showed us that Nb doping refines grains and enhances hardness. The hardness increases from 2.67 GPa of pure Zr to 2.99 GPa of Zr1.5Nb. Depending on the first-principles calculations, the hardness decreases with the increase in the Nb concentration in the Zr matrix, namely from 2.45 Gpa of pure Zr to 1.78 GPa of Zr1.5Nb. If the first-principles calculations indicate that the hardness decreases with the increase in the Nb concentration in the Zr matrix, grain refinement or defects could play a major role in the increase in hardness. Furthermore, regarding the effect of Nb doping on thermal expansion coefficients, the increase in Nb content causes the thermal expansion coefficients to decrease, which might stem from the strong binding energy between Nb and Zr atoms. The thermal conductivities of three samples show similar changing trends, indicating that thermal conductivity begins to decrease at room temperature and reaches a minimum value of around 400 °C. The thermal conductivity of pure zirconium samples is consistently higher, is more obvious than that of Nb-doped samples in the test range, and decreases with an increase in the doping concentration. The possible reasons for this might stem from the distortion of the Zr matrix due to Nb substitution doping and grain refinement, both of which cause phonon propagation scattering and thus hinder the propagation of phonons. The results obtained herein may be useful for the development of advanced nuclear fuels and waste forms that utilize zirconium in applications beyond their current usage.
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(This article belongs to the Special Issue Thermodynamics and Phase Transformation Kinetics Analysis of Alloy System)
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Barrier Properties of Cr/Ta-Coated Zr-1Nb Alloy under High-Temperature Oxidation
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Maxim Sergeevich Syrtanov, Stepan Pavlovich Korneev, Egor Borisovich Kashkarov, Dmitrii Vladimirovich Sidelev, Evgeny Nikolaevich Moskvichev and Viktor Nikolaevich Kudiiarov
Metals 2024, 14(6), 645; https://doi.org/10.3390/met14060645 - 29 May 2024
Abstract
In this paper, Cr (8 μm)/Ta (3 μm) bilayer coatings deposited on a Zr-1Nb alloy substrate were investigated and compared with a Cr-coated alloy under high-temperature steam oxidation at 1200–1400 °C. The bilayer coatings with α- and β-Ta interlayers were obtained by magnetron
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In this paper, Cr (8 μm)/Ta (3 μm) bilayer coatings deposited on a Zr-1Nb alloy substrate were investigated and compared with a Cr-coated alloy under high-temperature steam oxidation at 1200–1400 °C. The bilayer coatings with α- and β-Ta interlayers were obtained by magnetron sputtering. The Cr/Ta-coated samples were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), and optical microscopy (OM). The coating with an α-Ta interlayer can suppress the interdiffusion of chromium and zirconium more effectively up to 1330 °C in comparison with the coating having a β-Ta interlayer. The weight gain of the α-Ta-coated samples after oxidation at 1200 °C for 2000 s was 5–6 times lower than that of the Cr-coated Zr alloy samples. Oxidation at 1400 °C for 120 s showed no significant difference in the weight gain of the Cr- and Cr/Ta-coated Zr-1Nb alloy samples. It was shown that the effect of suppression of Zr-Cr interdiffusion by the barrier coating (α- and β-Ta) is only short-term.
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(This article belongs to the Special Issue High Temperature Corrosion or Oxidation of Metals and Alloys (2nd Edition))
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Open AccessArticle
On Dynamic Recrystallization during the Friction Stir Processing of Commercially Pure Ti and Its Influence on the Microstructure and Mechanical Properties
by
Michael Regev and Stefano Spigarelli
Metals 2024, 14(6), 644; https://doi.org/10.3390/met14060644 - 28 May 2024
Abstract
Friction stir processing (FSP), a severe plastic deformation process, was applied on commercially pure Ti to obtain an improved microstructure. The process yielded a refined microstructure and higher mechanical properties at room temperature (RT). Yet the microstructure was found to contain bright bands
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Friction stir processing (FSP), a severe plastic deformation process, was applied on commercially pure Ti to obtain an improved microstructure. The process yielded a refined microstructure and higher mechanical properties at room temperature (RT). Yet the microstructure was found to contain bright bands demonstrating high hardness values of about 500 HV. High-resolution scanning electron microscopy (HRSEM) as well as electron backscattering diffraction (EBSD) analysis indicated that these bands were composed of extra-fine equiaxed α-Ti grains with an average radius of 1–2 microns. In addition, a retained β phase was detected at the boundaries of these α-Ti grains, together with a small quantity of separate β grains. The results of a fractography study conducted on broken tensile specimens showed that the material that underwent FSP was free of defects and that the fracture started at these bands. It is proposed that these bright bands are due to excessive deformation occurring during the processing stage, leading to an accelerated dynamic recrystallization (DRX) process. In turn, these heavy deformation regions act as a strengthening constituent, making the material superior to the parent material as far as its mechanical RT properties are concerned. Consequently, this means that the FSP of CP-Ti has the potential to serve as an industrial means of improving the mechanical properties of the material.
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Open AccessArticle
Superelastic Properties of Aged FeNiCoAlTaB Cold-Rolled Shape Memory Alloys
by
Li-Wei Tseng, Miao Song, Wei-Cheng Chen, Yi-Ting Hsu and Chih-Hsuan Chen
Metals 2024, 14(6), 643; https://doi.org/10.3390/met14060643 - 28 May 2024
Abstract
In the present study, microstructure and cyclic tensile tests were used to measure the superelastic responses of Fe40.95Ni28Co17Al11.5Ta2.5B0.05 (at.%) shape memory alloys after 97% cold rolling. Cold-rolled samples underwent annealing heat treatment
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In the present study, microstructure and cyclic tensile tests were used to measure the superelastic responses of Fe40.95Ni28Co17Al11.5Ta2.5B0.05 (at.%) shape memory alloys after 97% cold rolling. Cold-rolled samples underwent annealing heat treatment (1250 °C/1 h) followed by quenching in water or aging heat treatment (700 °C/6 h and 700 °C/12 h) followed by quenching in water. The microstructure results showed that the average grain size increased from 210 μm to 1570 μm as annealing times increased from 0.5 h to 1 h. X-ray diffraction (XRD) spectra for FeNiCoAlTaB (NCATB) showed that in cold-rolled alloys after solution, the strong peak was in the face-centered cubic (γ, FCC) <111> structure. In aged samples, a new peak (γ’, FCC) emerged, the intensity of which increased as aging times rose from 6 to 12 h. Transmission electron microscope (TEM) images showed that the average precipitate size was around 10 nm in 700 °C/6 h specimens and 18 nm in 700 °C/12 h specimens. The precipitate was enriched in Ni, Al, and Ta elements and exhibited an L12 crystal structure. Tensile samples aged at 700 °C for 6 and 12 h exhibited recoverable strains of 1% and 2.6%, respectively, at room temperature. Digital image correlation (DIC) results for the sample aged at 700 °C for 12 h showed that two martensite variants were activated during the superelastic test. Such variants can form corresponding variant pairs (CVPs), which promote tensile deformation. The tensile sample exhibited a gradual cyclic degradation, and a large irrecoverable strain was observed after the test. This irrecoverable strain was the result of residual martensite, which was pinned by dislocations.
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(This article belongs to the Special Issue Feature Papers in Metallic Functional Materials)
Open AccessArticle
Texture Evolution and Plastic Deformation Mechanism of Cold-Drawn Co-Cr-Ni-Mo Alloy
by
Hanyuan Liu, Rui Hu, Xupeng Xia and Sen Yu
Metals 2024, 14(6), 642; https://doi.org/10.3390/met14060642 - 28 May 2024
Abstract
The plastic deformation behavior and mechanisms of Co-Cr-Ni-Mo alloy were investigated. The wires were subjected to different reductions using a multi-pass drawing approach and the resulting microstructures were characterized by EBSD and TEM. It was found that the alloy cold-drawn from surface to
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The plastic deformation behavior and mechanisms of Co-Cr-Ni-Mo alloy were investigated. The wires were subjected to different reductions using a multi-pass drawing approach and the resulting microstructures were characterized by EBSD and TEM. It was found that the alloy cold-drawn from surface to center exhibited non-uniform radial strain, with decreasing strain from surface to center. As the strain increased, the transverse texture of the alloy evolved from the initial bimodal texture consisting of strong {100}<110> and weak {110}<001> components to bimodal texture with {110}<233> and {112}<111> components, with significant twinning and mirror orientation between twin and matrix. The longitudinal texture evolution of the alloy mainly occurred on the α-fiber line, and ultimately did not form a significant texture due to grain elongation and crystal rotation. The plastic deformation mechanism of the Co-Cr-Ni-Mo alloy was dominated by dislocation slip at lower strain levels, which gradually transitioned to a combination of dislocation slip and twinning at higher strain levels. The deformation twins were typically distributed in high-density dislocation regions, and the twin boundaries transformed into high-angle sub-grain boundaries, hindering the extension of dislocation slip and deformation twin. With the increase in strain, work hardening results in a significant increase in strength and microhardness.
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(This article belongs to the Special Issue Metal Plastic Deformation and Forming)
Open AccessArticle
Failure Mechanism of Rear Drive Shaft in a Modified Pickup Truck
by
Zhichao Huang, Jiaxuan Wang, Yihua Hu, Yuqiang Jiang, Yong Xu and Xiongfei Wan
Metals 2024, 14(6), 641; https://doi.org/10.3390/met14060641 - 28 May 2024
Abstract
This paper investigates the failure mechanism of the rear drive shaft in a modified pickup truck which had operated for about 3000 km. The investigation included macroscopic and microscopic evaluation to document the morphologies of the fracture surface, measurement of the material composition,
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This paper investigates the failure mechanism of the rear drive shaft in a modified pickup truck which had operated for about 3000 km. The investigation included macroscopic and microscopic evaluation to document the morphologies of the fracture surface, measurement of the material composition, metallographic preparation and examination, mechanical testing, and finite element modelling and calculations. The results obtained suggest that rotation-bending fatigue was the primary cause of the drive shaft failure. The crack initiation is located in the root of the machined threads on the drive shaft surface and expanded along the side of the machining line surface. The main cause of fatigue cracks is attributable to a high stress concentration owing to a large unilateral bending impact under overload. Meanwhile, the bidirectional torsional force also produces a higher stress concentration and thus accelerates the fatigue crack to expand radially along the surface. Furthermore, the hardness of the central section of the drive shaft was marginally below standard. This deficiency results in harm to the bearings and other mechanical components, as well as expediting the enlargement of cracks. Finite element analysis revealed significant contact stress between the bearing and drive shaft, with stress levels exceeding the fatigue limit stress of the parent material. This highlights the need for reevaluation of the heat treatment process and vehicle loading quality to enhance the drive shaft’s longevity.
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(This article belongs to the Special Issue Failure of Metals: Fracture and Fatigue of Metallic Materials)
Open AccessReview
A Review of Fatigue Limit Assessment Using the Thermography-Based Method
by
Wei Wei, Lei He, Yang Sun and Xinhua Yang
Metals 2024, 14(6), 640; https://doi.org/10.3390/met14060640 - 28 May 2024
Abstract
Fatigue limit assessment methodologies based on the thermography technique are comprehensively studied in this work. Three fundamental indicators pertaining to temperature increase, intrinsic energy dissipation, and thermodynamic entropy are discussed in sequence. The main train of thought of thermo-based research is outlined. The
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Fatigue limit assessment methodologies based on the thermography technique are comprehensively studied in this work. Three fundamental indicators pertaining to temperature increase, intrinsic energy dissipation, and thermodynamic entropy are discussed in sequence. The main train of thought of thermo-based research is outlined. The main objective of this paper is, on the one hand, to describe some works that have been accomplished in this field and, on the other hand, to present further potential for future studies involving fatigue behaviors and thermography approaches.
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(This article belongs to the Section Structural Integrity of Metals)
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Open AccessArticle
Effect of Molten Salts Composition on the Corrosion Behavior of Additively Manufactured 316L Stainless Steel for Concentrating Solar Power
by
Najib Abu-warda, Sonia García-Rodríguez, Belén Torres, María Victoria Utrilla and Joaquín Rams
Metals 2024, 14(6), 639; https://doi.org/10.3390/met14060639 - 28 May 2024
Abstract
The effects of different molten salts on the corrosion resistance of laser powder bed fusion (L-PBF) 316L stainless steel was evaluated at 650 and 700 °C. The samples were characterized via XRD and SEM/EDX after high-temperature corrosion tests to evaluate the corrosion damage
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The effects of different molten salts on the corrosion resistance of laser powder bed fusion (L-PBF) 316L stainless steel was evaluated at 650 and 700 °C. The samples were characterized via XRD and SEM/EDX after high-temperature corrosion tests to evaluate the corrosion damage to the L-PBF 316L stainless steel caused by the molten salts. The presence of the salts accelerated the corrosion process, the chloride-based salts being the most aggressive ones, followed by the carbonate-based and the nitrate/nitrite-based salts, respectively. The L-PBF 316L did not react strongly with the nitrate/nitrite-based salts, but some corrosion products not found in the samples tested in the absence of salts, such as NaFeO2, were formed. LiFeO2 and LiCrO2 were identified as the main corrosion products in the samples exposed to the carbonate-based molten salts, due to the high activity of Li ions. Their growth produced the depletion of Fe and Cr elements and the formation of vacancies that acted as diffusion paths on the surface of the steel. In the samples exposed to chloride-based molten salts, the attacked area was much deeper, and the corrosion process followed an active oxidation mechanism in which a chlorine cycle is assumed to have been involved.
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(This article belongs to the Special Issue Novel Insights and Advances in Steels and Cast Irons)
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Open AccessArticle
Neutron Diffraction Measurements of Residual Stresses for Ferritic Steel Specimens over 80 mm Thick
by
Vyacheslav Em, Karpov Ivan, Wanchuck Woo and Pavol Mikula
Metals 2024, 14(6), 638; https://doi.org/10.3390/met14060638 - 28 May 2024
Abstract
The maximum thickness for ferritic steel specimens’ residual stress measurements using neutron diffraction is known to be about 80 mm. This paper proposes a new neutron diffraction configuration of residual stress measurements for cases that are over 80 mm thick. The configuration utilizes
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The maximum thickness for ferritic steel specimens’ residual stress measurements using neutron diffraction is known to be about 80 mm. This paper proposes a new neutron diffraction configuration of residual stress measurements for cases that are over 80 mm thick. The configuration utilizes a neutron beam with a wavelength of 1.55 Å diffracted from the (220) plane with a diffraction angle (2θ) of 99.4°. The reason for the deep penetration capability is attributed to the chosen wavelength having enough intensities due to the low cross-section near the Bragg edge and the reduced beam path length (~16 mm) reflected by the large diffraction angle. Neutron diffraction experiments with this configuration can decrease strain errors up to ±150 με, corresponding to a stress of about ±30 MPa.
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(This article belongs to the Special Issue Characterization and Modeling on Complex Metallic Materials)
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