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Metals, Volume 14, Issue 7 (July 2024) – 77 articles

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13 pages, 5842 KiB  
Communication
A Comparative Analysis of a Microstructure and Properties for Monel K500 Hot-Rolled to a Round Bar and Wire Deposited on a Round Surface
by Andrii Kostryzhev, Olexandra Marenych, Zengxi Pan, Huijun Li and Stephen van Duin
Metals 2024, 14(7), 813; https://doi.org/10.3390/met14070813 (registering DOI) - 13 Jul 2024
Viewed by 117
Abstract
Metal manufacturing processes based on deformation (forging, rolling) result in a fine grain structure with a complex dislocation substructure, which positively influence mechanical properties. Casting and additive manufacturing (powder- or wire-based) usually produce a coarse grain structure with a poorly developed dislocation substructure, [...] Read more.
Metal manufacturing processes based on deformation (forging, rolling) result in a fine grain structure with a complex dislocation substructure, which positively influence mechanical properties. Casting and additive manufacturing (powder- or wire-based) usually produce a coarse grain structure with a poorly developed dislocation substructure, which negatively affect mechanical properties. Heat treatment may alter phase balance and stimulate precipitation strengthening; however, precipitation kinetics depends on the dislocation substructure. In this paper, a comparative study of the microstructure and strength is presented for Monel K500 alloy containing 63 Ni, 30 Cu, 2.0 Mn, and 2.0 Fe (wt.%), and microalloyed with Al, Ti, and C hot-rolled to a round bar and deposited on a round surface using wire additive manufacturing (WAAM) technology. An increased dislocation density and number density of fine precipitates resulted in 8–25% higher hardness and 1.8–2.6 times higher compression yield stress in the hot-rolled alloy compared to these in the WAAM-produced alloy. However, due to a high work hardening rate, only 3–10% cold deformation was necessary to increase the strength of the WAAM alloy to this of the hot-rolled one. Age hardening heat treatment, through the intensification of the precipitation strengthening mechanism, reduced the value of cold deformation strain required to equalise the properties. Based on the obtained results, a new technology consisting of additive manufacturing, heat treatment, and cold deformation can be proposed. It can produce WAAM components with strength and hardness improved to the level of hot-rolled components, which is a significant development of additive manufacturing. Full article
(This article belongs to the Section Additive Manufacturing)
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20 pages, 16297 KiB  
Article
Study on the Influence of Surface Roughness and Temperature on the Interface Void Closure and Microstructure Evolution of Stainless Steel Diffusion Bonding Joints
by Yanni Wei, Shuyuan Zhang, Lei Jia, Quanning Li and Mengfan Ma
Metals 2024, 14(7), 812; https://doi.org/10.3390/met14070812 - 12 Jul 2024
Viewed by 263
Abstract
Austenitic stainless steel diffusion bonding was performed, and the effects of the surface roughness and bonding temperature on the interface microstructure and mechanism of hole closure were investigated. The bonded interface microstructure was analyzed. The influence of surface roughness and temperature on cavity [...] Read more.
Austenitic stainless steel diffusion bonding was performed, and the effects of the surface roughness and bonding temperature on the interface microstructure and mechanism of hole closure were investigated. The bonded interface microstructure was analyzed. The influence of surface roughness and temperature on cavity evolution, bonding rate, and axial deformation rate was studied. The mechanism of interfacial void closure in the stainless steel diffusion bonding process was revealed. With the increase in temperature and the decrease in surface roughness, the size of the interface void and the bonded area decreased. The bonding rate can reach more than 95% when the surface roughness value is 0.045 μm and the temperature is at or higher than 750 °C. The analytical equations of interfacial bonding rate δ and axial deformation rate ε produced by the deformation mechanism were established, and the laws of the deformation mechanism and diffusion mechanism within interfacial hole closure were obtained. Full article
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15 pages, 3709 KiB  
Article
Modeling and Research on the Defects of Pressed Rigging in a Geomagnetic Field Based on Finite Element Simulation
by Gang Zhao, Changyu Han, Zhongxiang Yu, Hongmei Zhang, Dadong Zhao, Guoao Yu and Zhengyi Jiang
Metals 2024, 14(7), 811; https://doi.org/10.3390/met14070811 - 12 Jul 2024
Viewed by 178
Abstract
It is very important to carry out effective safety inspections on suppression rigging because of the bad service environment of suppression rigging: marine environments. In this paper, the multi-parameter simulation method in ANSYS and ANSYS Electronics Suite simulation software is used to simulate [...] Read more.
It is very important to carry out effective safety inspections on suppression rigging because of the bad service environment of suppression rigging: marine environments. In this paper, the multi-parameter simulation method in ANSYS and ANSYS Electronics Suite simulation software is used to simulate the effect of geomagnetic fields on the magnetic induction intensity of defective pressed rigging under the variable stress in marine environments. The results of the ANSYS simulation and geomagnetic flaw detection equipment are verified. The simulation results show that, according to the multi-parameter simulation results of ANSYS and ANSYS Electronics Suite simulation software, it can be found that, under the action of transverse force, the internal stress of the pressed rigging will affect the magnetic field around pressed rigging with defects. With an increase in internal stress in the range of 0~20 MPa, the magnetic induction intensity increases to 0.55 A/m, and with an increase in internal stress in the range of 20~150 MPa, the magnetic induction intensity decreases to 0.06 A/m. From the use of a force magnetic coupling analysis method, it can be obtained, under the lateral force of the defects in suppressing rigging, that magnetic flux leakage signals decrease with an increase in the rigging’s radial distance. The experiment results show that the difference between the peak and trough of the magnetic induction intensity at the pressed rigging defect calculated by the ANSYS simulation is very consistent with the results measured by the geomagnetic flaw detection equipment. Full article
(This article belongs to the Special Issue Modeling Thermodynamic Systems and Optimizing Metallurgical Processes)
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14 pages, 7016 KiB  
Article
Influence of Surface State on the Corrosion Behavior of Si-Reinforced F/M Steels under Solid-Phase Oxygen-Controlled Static Liquid LBE Environment
by Yuchen Liu, Bo Qin, Xiaogang Fu and Bin Long
Metals 2024, 14(7), 810; https://doi.org/10.3390/met14070810 - 11 Jul 2024
Viewed by 208
Abstract
Since F/M steel is one of the leading candidate materials for the lead-cooled fast reactor (LFR), its compatibility with the liquid LBE environment is an essential issue before application. One major way to improve LBE corrosion resistance is to control the oxygen concertation [...] Read more.
Since F/M steel is one of the leading candidate materials for the lead-cooled fast reactor (LFR), its compatibility with the liquid LBE environment is an essential issue before application. One major way to improve LBE corrosion resistance is to control the oxygen concertation in liquid LBE for the growth of a stable, protective oxide layer on the surface of the structure material. However, the influence of the surface state on corrosion behavior is a more realistic issue when it comes to practical applications. In this study, the corrosion behavior of Si-reinforced 9Cr and 11Cr F/M steels with different surface states was investigated by a static liquid LBE corrosion test under solid-phase oxygen-controlled conditions. The result showed that at 550 °C, the coarse surface state caused dissolution behavior at the initial stage of corrosion, while the fine surface state formed the oxide layer. Moreover, at 610 °C, Si-reinforced 11Cr F/M steel shows better liquid LBE corrosion resistance due to its thinner oxide layer formation. Full article
(This article belongs to the Section Corrosion and Protection)
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22 pages, 15916 KiB  
Article
Inconel 740H Prepared by Additive Manufacturing: Microstructure and Mechanical Properties
by Ruizhang Hu, Wenqing Li, Chun Guo, Guangcan Huang, Xinyu Zhang and Qingcheng Lin
Metals 2024, 14(7), 809; https://doi.org/10.3390/met14070809 - 11 Jul 2024
Viewed by 221
Abstract
An Inconel 740H nickel-based alloy was fabricated via wire arc additive manufacturing. The as-welded and heat-treated samples were analyzed to investigate their phase composition, microstructure, crystal structure, and mechanical properties. After heat treatment, the sample exhibited a columnar crystal zone microstructure consisting of [...] Read more.
An Inconel 740H nickel-based alloy was fabricated via wire arc additive manufacturing. The as-welded and heat-treated samples were analyzed to investigate their phase composition, microstructure, crystal structure, and mechanical properties. After heat treatment, the sample exhibited a columnar crystal zone microstructure consisting of a γ matrix + precipitated phase, the remelting zone metallographic structure was a γ matrix + precipitated phase, and the HAZ metallographic structure was a γ matrix + precipitated phase. Transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) were used to show that the welded sample exhibited many dislocations, a few inclusions, and carbides, nitrides, and γ’ precipitates in its crystal structure. In contrast, the crystal structure of the heat-treated sample exhibited a lower number of dislocations and significantly higher carbide and γ’ precipitate content. Moreover, the mechanical performance of these samples was excellent. This heat-treatment process improved the sample strength by about 200 MPa, leading to better high-temperature mechanical properties. This work is anticipated to offer theoretical and experimental support for using additive manufacturing methods in the manufacturing of nickel-based superalloy components. Full article
(This article belongs to the Section Additive Manufacturing)
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13 pages, 4243 KiB  
Article
An Insight into the Varying Effects of Different Cryogenic Temperatures on the Microstructure and the Thermal and Compressive Response of a Mg/SiO2 Nanocomposite
by Michael Johanes, Sarah Mehtabuddin, Vishal Venkatarangan and Manoj Gupta
Metals 2024, 14(7), 808; https://doi.org/10.3390/met14070808 - 11 Jul 2024
Viewed by 183
Abstract
This study for the first time reports that insights into microstructure and thermal and compressive responses can be best achieved following exposure to different cryogenic temperatures and that the lowest cryogenic temperature may not always produce the best results. In the present study, [...] Read more.
This study for the first time reports that insights into microstructure and thermal and compressive responses can be best achieved following exposure to different cryogenic temperatures and that the lowest cryogenic temperature may not always produce the best results. In the present study, a Mg-SiO2 biocompatible and environment-friendly nanocomposite was synthesized by using the Disintegrated Melt Deposition method followed by hot extrusion. Subsequently, it was subjected to four different sub-zero temperatures (−20 °C, −50 °C, −80 °C, and −196 °C). The results reveal the best densification at −80 °C, marginally improved ignition resistance at 50 °C, the best damping response at −80 °C, the best microhardness at −50 °C, and the best compressive response at −20 °C. The results clearly indicate that the cryogenic temperature should be carefully chosen depending on the property that needs to be particularly enhanced governed by the principal requirement of the end application. Full article
(This article belongs to the Special Issue Design and Development of Metal Matrix Composites)
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17 pages, 23489 KiB  
Article
Ductile-to-Brittle Transition of Steel Due to Dynamic Loading
by Gianmario Riganti and Ezio Cadoni
Metals 2024, 14(7), 807; https://doi.org/10.3390/met14070807 - 11 Jul 2024
Viewed by 172
Abstract
The transition from ductile to brittle for metals is usually encountered during fast machining operations, in low-temperature environments, and in all situations involving very high strain rates. Traditionally, classical material models used in the dynamic structural analysis focus on the plastic-stress-versus-strain rate. As [...] Read more.
The transition from ductile to brittle for metals is usually encountered during fast machining operations, in low-temperature environments, and in all situations involving very high strain rates. Traditionally, classical material models used in the dynamic structural analysis focus on the plastic-stress-versus-strain rate. As a result, those models cannot incorporate sudden changes in failure strains and strengths triggered by material behavior transition. The ability to predict realistically the dynamic behavior of structures based on physical constitutive equations depends on having a comprehensive understanding of such drastic changes in material behavior. This transition is described by the DAMP-PLAST model, incorporating constitutive equations and governed by the shear band speed parameter at a finite time. After the development of the equation set, the material model is tested in regard to its ability to produce three distinguished material responses: elastic-plastic, elastic–plastic with strain-rate sensitivity, and brittle with increased dynamic failure strength. The study identifies metal dynamic brittleness linked to a critical loading rate influencing the plastic flow process. Based on this relation, the identification of the critical loading rate using split Hopkinson bar apparatus, and material constitutive equation is proposed. Full article
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13 pages, 4211 KiB  
Article
Effects of Post-Weld Heat Treatment on the Microstructure and Mechanical Properties of Automatic Laser-Arc Hybrid Welded AZ31B Magnesium Alloys
by Jin Xiong, Ruochao Wang, Dongqing Zhao, Hongtao Liu and Jixue Zhou
Metals 2024, 14(7), 806; https://doi.org/10.3390/met14070806 - 10 Jul 2024
Viewed by 206
Abstract
The aim of this study was to determine the microstructural evolution, tensile characteristics, and strain-hardening response of AZ31B magnesium alloy welds as influenced by post-weld heat treatment (PWHT). Thus, the AZ31B alloy was welded by using a low-power pulsed Nd:YAG laser-arc hybrid welding [...] Read more.
The aim of this study was to determine the microstructural evolution, tensile characteristics, and strain-hardening response of AZ31B magnesium alloy welds as influenced by post-weld heat treatment (PWHT). Thus, the AZ31B alloy was welded by using a low-power pulsed Nd:YAG laser-arc hybrid welding equipped on the six-axis welding robot in the present study. Microstructure, mechanical properties and strain-hardening behaviors of the AZ31B joints under various post-weld heat treatment (PWHT) temperatures were characterized. As the heat treatment temperature increases, the grain size of the welded joint gradually increases, and the amount of β-Mg17AI12 phase noticeably decreases. The mechanical properties of the welded joint specimens showed a significant enhancement when subjected to heat treatment at 300 °C and 350 °C for 20 min. Especially, after 350 °C heat treatment for 20 min, the ultimate tensile strength (UTS) and elongation (EL) of specimen were 339.6 MPa and 20.1%, respectively, which were up to 99.5% and 98.5% of the AZ31B base material (BM). The strain-hardening capacity of specimens is significantly influenced by the grain size. Due to having the largest grain size, the 400–20 min specimen exhibited the highest hardening capacity and strain hardening exponent. In Kocks-Mecking type curves, both stage III and stage IV were observed in BM and joint specimens. At higher net flow stresses, the strain hardening rate in the 400–20 min joint specimen was higher due to the larger grains, which allowed for more dislocation accommodation and improved the capacity for dislocation storage. Full article
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18 pages, 16168 KiB  
Article
Effect of Scanning Strategy on Microstructure Evolution and Stress Control in Laser Cladding Repair of Ti6Al4V Alloy
by Zhoucheng Liu, Jinsheng Ji, Qiang Wang, Xiaohu Guan, Leilei Wang and Xiaohong Zhan
Metals 2024, 14(7), 805; https://doi.org/10.3390/met14070805 - 10 Jul 2024
Viewed by 200
Abstract
Laser cladding provides a cost-effective and high-quality solution for repairing aircraft engines. A finite element model was developed in this study to simulate and analyze the stress distribution during the cladding of a complex curved groove structure made of Ti6Al4V. The mechanism underlying [...] Read more.
Laser cladding provides a cost-effective and high-quality solution for repairing aircraft engines. A finite element model was developed in this study to simulate and analyze the stress distribution during the cladding of a complex curved groove structure made of Ti6Al4V. The mechanism underlying the microstructure at the interface was revealed. The stress concentration locations in the curved groove structure are located at the intersection of the cladding layer and sidewall, as well as at both ends of the cladding layer and the groove bottom. By applying reverse swing scanning, a more consistent distribution of stress fields can be obtained. Optimizing the scanning strategy reduced the maximum stress in the repair layer from 717 MPa to 711 MPa. The experimental stress distribution data are in good agreement with the computational results. The cladding layer undergoes changes in heat cycling and nucleation conditions, leading to the formation of alternating columnar and equiaxed grain morphologies. Full article
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29 pages, 1160 KiB  
Review
Technospheric Mining of Critical and Strategic Metals from Non-Ferrous Slags
by Bona Lim, Mark Aylmore and Richard Diaz Alorro
Metals 2024, 14(7), 804; https://doi.org/10.3390/met14070804 - 10 Jul 2024
Viewed by 612
Abstract
The technosphere consists of material stocks accumulated by human activities, which can include processing residue, such as slag. Various smelting processes generate slag, and some valuable elements are concentrated in this by-product. In this review, the extraction of critical and strategic metals from [...] Read more.
The technosphere consists of material stocks accumulated by human activities, which can include processing residue, such as slag. Various smelting processes generate slag, and some valuable elements are concentrated in this by-product. In this review, the extraction of critical and strategic metals from non-ferrous slags is discussed. Critical and strategic metals are materials that are vital for the nation’s economy and defence, as well as its industries, and have common features, such as expected shortfalls, increasing demand, and few substitutions. There are several definitions, methods, and classifications of critical and strategic elements by different organisations. In this study, reports from seven institutions around the world are summarised, and a list of recommended critical and strategic metals is presented. Non-ferrous slags contain a considerable amount of critical and strategic elements, and research on technology and process development using both pyro- and hydrometallurgical methods is very attractive. When it comes to the extraction of values from slag and the development of technology, it is not only important to consider the economic aspect but also to ensure the processes are low in emissions and energy consumption but high in efficiency and recycling. Full article
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19 pages, 9846 KiB  
Article
Effect of Bi on the Tensile and Viscoplastic Behavior of Sn-Ag-Cu-Bi Alloys Used for Microelectronics Applications
by Vishnu Shukla, Omar Ahmed, Peng Su, Tian Tian and Tengfei Jiang
Metals 2024, 14(7), 803; https://doi.org/10.3390/met14070803 - 9 Jul 2024
Viewed by 252
Abstract
Sn-Ag-Cu-Bi (SAC-Bi) alloys are gaining popularity as a potential replacement for current lead-free solder alloys in microelectronic packages. In this study, the tensile and viscoplastic behaviors of eight SAC-Bi alloys with 0, 1 wt.%, 2 wt.%, and 3 wt.% Bi content were investigated. [...] Read more.
Sn-Ag-Cu-Bi (SAC-Bi) alloys are gaining popularity as a potential replacement for current lead-free solder alloys in microelectronic packages. In this study, the tensile and viscoplastic behaviors of eight SAC-Bi alloys with 0, 1 wt.%, 2 wt.%, and 3 wt.% Bi content were investigated. The samples of these eight alloys were cast, aged at room temperature, 75 °C and 125 °C, and tensile-tested at rates of 0.1/s, 0.01/s, and 0.001/s in ambient and elevated temperature environments to facilitate the quantification of viscoplasticity using the Anand viscoplastic model. The Anand parameters of all eight alloys in the as-cast and aged conditions were determined. Tensile strength was found to increase with the addition of Bi. Additionally, alloys containing 2 and 3 wt.% Bi showed a 5 to 10% increase in tensile strength after isothermal aging of 90 days at 125 °C. On the contrary, the tensile strength of alloys with up to 1 wt.% Bi decreased by 22 to 48% after such aging. Using a Scanning Electron Microscope (SEM) and energy dispersive spectroscopy (EDS), the microstructure of the alloys was characterized. The aging-induced property changes in the samples were correlated to strengthening by Bi solute atoms for alloys with 1 wt.% Bi and the formation of Bi precipitation for alloys with 2 wt.% and 3 wt.% Bi. Full article
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11 pages, 4458 KiB  
Article
Phase Transformation of AlV55 Alloy at High Temperature
by Leizhang Gao, Haijun Chen, Danfeng Yin, Ning Wang, Bin Yu, Mingfeng Ye, Xiaoping Wu, Lei Zhang and Jinshu Wu
Metals 2024, 14(7), 802; https://doi.org/10.3390/met14070802 - 9 Jul 2024
Viewed by 241
Abstract
Vanadium–aluminum alloy is an important intermediate alloy for preparing aviation grade titanium alloys, and its product quality directly affects the finished product quality of titanium alloys. In this study, focusing on the problems of high powder content (19.8%) and low product yield in [...] Read more.
Vanadium–aluminum alloy is an important intermediate alloy for preparing aviation grade titanium alloys, and its product quality directly affects the finished product quality of titanium alloys. In this study, focusing on the problems of high powder content (19.8%) and low product yield in AlV55 alloy products, we conduct research on alloy quality control technology and implement a vanadium–aluminum alloy cooling crystallization control process. The research results indicate that there are three phases in AlV55 alloy, namely Al8V5, AlV, and Al2V3 phases. As the temperature decreases, the AlV phase gradually decomposes into Al8V5 phase and Al2V3 phase, and the proportion of Al8V5 phase is positively correlated with the fineness. Rapid cooling can reduce the formation of Al8V5 phase. The experimental results show that high-temperature water quenching can increase the proportion of vanadium–aluminum solid solution phase in the alloy from 19.03% to 31.76%, and reduce the fine powder rate to 13.2%, providing important product quality control means and technical support for the production of vanadium–aluminum alloys. Full article
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13 pages, 2301 KiB  
Article
Preparation and Property Modulation of Multi-Grit Diamond/Aluminum Composites Based on Interfacial Strategy
by Hao Wu, Sen Yang, Yang Chen, Xiaoxuan He and Changrui Wang
Metals 2024, 14(7), 801; https://doi.org/10.3390/met14070801 - 9 Jul 2024
Viewed by 320
Abstract
The development of electronic devices has a tendency to become more complicated in structure, more integrated in function, and smaller in size. The heat flow density of components continues to escalate, which urgently requires the development of heat sink materials with high thermal [...] Read more.
The development of electronic devices has a tendency to become more complicated in structure, more integrated in function, and smaller in size. The heat flow density of components continues to escalate, which urgently requires the development of heat sink materials with high thermal conductivity and a low coefficient of expansion. Diamond/aluminum composites have become the research hotspot of thermal management materials with excellent thermophysical and mechanical properties, taking into account the advantages of light weight. In this paper, diamond/Al composites are prepared by combining aluminum as matrix and diamond reinforcement through the discharge plasma sintering (SPS) method. The micro-interfacial bonding state of diamond and aluminum is changed by adjusting the particle size of diamond, and the macroscopic morphology performance of the composites is regulated. Through this, the flexible design of diamond/Al performance can be achieved. As a result, when 150 μm diamond powder and A1-12Si powder were used for the composite, the thermal conductivity of the obtained specimens was up to 660.1 W/mK, and the coefficient of thermal expansion was 5.63 × 10−6/K, which was a good match for the semiconductor material. At the same time, the bending strength is 304.6 MPa, which can satisfy the performance requirements of heat-sinking materials in the field of electronic packaging. Full article
(This article belongs to the Special Issue Functional Ceramics and Related Advanced Metal Matrix Composites)
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15 pages, 4628 KiB  
Article
Development of a Dezincification-Free Alloy System for the Manufacturing of Brass Instruments
by Susanne Berndorf, Anatol Markelov, Sergey Guk, Marcel Mandel, Lutz Krüger and Ulrich Prahl
Metals 2024, 14(7), 800; https://doi.org/10.3390/met14070800 - 9 Jul 2024
Viewed by 390
Abstract
Conventionally used brass alloy CuZn30 shows problems with corrosion resistance in the form of dezincification when used in brass instruments. Therefore, within the scope of this investigation, a new brass alloy CuZn30 is developed in the microalloy range with corrosion-free or corrosion-inhibiting properties. [...] Read more.
Conventionally used brass alloy CuZn30 shows problems with corrosion resistance in the form of dezincification when used in brass instruments. Therefore, within the scope of this investigation, a new brass alloy CuZn30 is developed in the microalloy range with corrosion-free or corrosion-inhibiting properties. First, the influence of microalloying elements on the phase composition is investigated by simulation using Thermo-Calc. On the basis of this, suitable alloying elements and contents are selected and a modified CuZn30X alloy with 0.1% phosphorus, tin, and nickel in mass fractions, respectively, is produced. The modified alloy is then investigated with regard to its mechanical and microstructural composition and its corrosion properties. The corrosion properties were examined using stress corrosion cracking tests, dezincification tests, and the recording of polarization curves. The modified alloy exhibited good cold and hot rolling properties as well as good corrosion resistance. The dezincification test confirmed the improved corrosion resistance of the modified CuZn30X alloy, which is attributed to the formation of a protective top layer due to the alloying elements. Full article
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18 pages, 2266 KiB  
Article
Impact of 5-Amino-1H Tetrazole on Reducing Silver in Copper Cathodes during Electrorefining with High Silver Content Anode Plates
by Chen Chen, Chu Cheng, Mengxin Wang, Haitao Liu, Xiaoheng Li and Kexing Song
Metals 2024, 14(7), 799; https://doi.org/10.3390/met14070799 - 8 Jul 2024
Viewed by 340
Abstract
As the grade of the copper concentrate decreases and its composition becomes increasingly complex, the silver content in anode plates cast after fire refining increases, leading to a higher silver content in the copper cathode during electrorefining and a substantial loss of precious [...] Read more.
As the grade of the copper concentrate decreases and its composition becomes increasingly complex, the silver content in anode plates cast after fire refining increases, leading to a higher silver content in the copper cathode during electrorefining and a substantial loss of precious metals. This study investigates the impact of 5-amino-1H tetrazole (5-AT) on reducing silver in copper cathodes during electrorefining with high silver content anode plates. 5-AT forms an “adsorption layer” on the anode surface, reacting with Ag+ released by the anode to form a precipitate and prevent Ag+ from entering the electrolyte. This process agglomerates fine Ag-Se compounds and AgCl particles, creating larger anode slime particles that settle quickly, thus inhibiting fine silver-containing particles from adhering to the cathode. Furthermore, 5-AT adsorbs on the cathode, binding with Cu+ and promoting the Cu2+ electrodeposition process while inhibiting Ag+ electrodeposition. This facilitates uniform copper cathode grain growth and reduces inclusions in the copper cathode. The grain size of the copper cathode initially decreases and then increases as the concentration of 5-AT increases. At an optimal 5-AT concentration of 15 mg/L, the Ag content in the copper cathode decreased from 6.9 ppm to 4.7 ppm, indicating the potential efficacy of 5-AT in improving the quality of electrorefined copper. Full article
(This article belongs to the Special Issue Separation and Purification of Metals (Second Edition))
27 pages, 2261 KiB  
Article
Research on Blast Furnace Ingredient Optimization Based on Improved Grey Wolf Optimization Algorithm
by Ran Liu, Zi-Yang Gao, Hong-Yang Li, Xiao-Jie Liu and Qing Lv
Metals 2024, 14(7), 798; https://doi.org/10.3390/met14070798 - 8 Jul 2024
Viewed by 388
Abstract
Blast furnace ironmaking plays an important role in modern industry and the development of the economy. A reasonable ingredient scheme is crucial for energy efficiency and emission reduction in blast furnace production. Determining the right blast furnace ingredients is a complicated process; therefore, [...] Read more.
Blast furnace ironmaking plays an important role in modern industry and the development of the economy. A reasonable ingredient scheme is crucial for energy efficiency and emission reduction in blast furnace production. Determining the right blast furnace ingredients is a complicated process; therefore, this study examines the optimization of the ingredient ratio. In this paper a model of the blast furnace ingredients is established by considering cost of per ton iron, CO2 emissions, and the theoretical coke ratio as the objective functions; ingredient parameters, process parameters, main and by-product parameters as variables; and the blast furnace smelting theory and equilibrium equation as constraints. Then, the model is solved by using an improved grey wolf optimization algorithm and an improved multi-objective grey wolf optimization algorithm. Using the data collected from the steel mill, the conclusion is that multi-objective optimization can consider the indexes of each target, so that the values of all the targets are excellent; we also compared the multi-objective solution results with the original production scheme of the steel mill, and we found that using the blast furnace ingredient scheme optimized in this study can reduce the cost of iron per ton, CO2 emissions per ton, and the theoretical coke ratio in blast furnace production by 350 CNY/t, 1000 kg/t, and 20 kg/t, respectively, compared with the original production plan. Thus, steel mill decision makers can choose the blast furnace ingredients according to different business strategies and the actual needs of steel mills can be better met. Full article
(This article belongs to the Special Issue Advanced Metal Smelting Technology and Prospects)
17 pages, 2542 KiB  
Article
High-Performance 2319 Aluminum Alloy via CMT-WAAM: Microstructure, Porosity, and Mechanical Properties
by Yuxin Pan, Ming Yu, Chao Xu, Jianchao Zhang and Lin Geng
Metals 2024, 14(7), 797; https://doi.org/10.3390/met14070797 - 8 Jul 2024
Viewed by 314
Abstract
The process of cold metal transfer (CMT) wire arc additive manufacturing (WAAM) for 2319 aluminum alloy was studied. The research investigated the coarse and fine equiaxed grain bands and porosity of the 2319 alloy after solution aging treatment, with a focus on the [...] Read more.
The process of cold metal transfer (CMT) wire arc additive manufacturing (WAAM) for 2319 aluminum alloy was studied. The research investigated the coarse and fine equiaxed grain bands and porosity of the 2319 alloy after solution aging treatment, with a focus on the mechanical properties and deformation behavior of the aluminum alloy at different positions and orientations. Pores and coarse second phases mainly appeared at grain boundaries but were also observed within coarse equiaxed grains. The yield strength of the top horizontal samples reached 325.5 MPa, one of the highest yield strengths reported for 2319 aluminum alloy in the literature. The coarse brittle second phases at grain boundaries were the main crack sources during the failure process of the samples. In the fine equiaxed grain layer, cracks propagated along the grain boundaries connected to the second phases, and the presence of pores accelerated crack propagation; in the coarse equiaxed grain layer, cracks directly penetrated through the grains. Full article
19 pages, 6132 KiB  
Article
Thixoforming of the Hot Extruded Aluminum AlSi9Cu3(Fe) Machining Chips
by Jure Krolo, Ivana Dumanić Labetić, Branimir Lela and Martin Bilušić
Metals 2024, 14(7), 796; https://doi.org/10.3390/met14070796 - 8 Jul 2024
Viewed by 297
Abstract
The main aim of this research was to investigate the aluminum AlSi9Cu3(Fe) machining chips recycling possibility utilizing a direct hot extrusion process and thixoforming. The thixo feedstock was prepared directly from the aluminum alloy AlSi9Cu3(Fe) machining chips waste without any remelting step. The [...] Read more.
The main aim of this research was to investigate the aluminum AlSi9Cu3(Fe) machining chips recycling possibility utilizing a direct hot extrusion process and thixoforming. The thixo feedstock was prepared directly from the aluminum alloy AlSi9Cu3(Fe) machining chips waste without any remelting step. The machining chips were compacted, and direct hot extruded to create the solid samples and thixo feedstock. The aluminum alloy AlSi9Cu3(Fe) machining chips had a high degree of plastic deformation and after extrusion and heating in the semisolid temperature range, the suitable globular microstructure was achieved, which is a precondition for a successful thixoforming process. This approach can be characterized as a semisolid recycling process with a lower energy consumption, a higher material yield, and reduced greenhouse gas emissions into the atmosphere compared with conventional casting and recycling. Optical metallography, scanning electron microscopy accompanied with energy dispersive spectroscopy, electrical conductivity, and mechanical properties investigation were performed on the reference casted sample with a dendritic microstructure, the extruded sample with a severely deformed microstructure, and finally the thixoformed samples with a globular microstructure produced with different parameters, according to the Taguchi L4 (23) experimental plan. Full article
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14 pages, 1774 KiB  
Article
Achieving Homogeneous Microstructure and Superior Properties in High-N Austenitic Stainless Steel via a Novel Atmosphere-Switching Method
by Weipeng Zhang, Liejun Li, Chengcheng Huang, Jixiang Gao, Liming Zou, Zhuoran Li and Zhengwu Peng
Metals 2024, 14(7), 795; https://doi.org/10.3390/met14070795 - 8 Jul 2024
Viewed by 322
Abstract
Powder metallurgy is widely used to fabricate high-nitrogen, nickel-free austenitic stainless steel. However, after sintering and nitriding, additional solution treatment is typically required to achieve uniform nitrogen distribution and a homogeneous austenite phase. This work proposes a novel method to eliminate the need [...] Read more.
Powder metallurgy is widely used to fabricate high-nitrogen, nickel-free austenitic stainless steel. However, after sintering and nitriding, additional solution treatment is typically required to achieve uniform nitrogen distribution and a homogeneous austenite phase. This work proposes a novel method to eliminate the need for lengthy and high-temperature solution treatment by switching the nitrogen atmosphere to argon during the cooling process. The effects of different N2-Ar atmosphere-switching temperatures (750–1320 °C) on the phase composition, element distribution, microstructure, mechanical properties, and corrosion resistance of the studied steels were systematically investigated. Results show that cooling in the N2 atmosphere initially transforms the matrix to a fully austenitic structure enriched with nitrogen. Excessive nitrogen infiltration leads to Cr2N precipitation, inducing partial austenite decomposition and forming a multiphase structure comprising austenite, α-Fe, and Cr2N. Strategic switching from N2 to Ar reverses this reaction, yielding a high-nitrogen, chemically uniform austenitic structure. Specifically, switching at 1150 °C, the steel exhibits excellent mechanical properties and corrosion resistance, with a yield strength of 749 MPa, an ultimate tensile strength of 1030 MPa, an elongation of 38.7%, and a corrosion current of 0.06 mA/cm2, outperforming the steels cooled solely in N2 and subsequently solution-treated. This novel method offers advantages in cost reduction, energy saving, and operational effectiveness, highlighting its potential for broad industrial application. Full article
15 pages, 7256 KiB  
Article
Precipitation Behavior and Strengthening–Toughening Mechanism of Nb Micro-Alloyed Direct-Quenched and Tempered 1000 MPa Grade High-Strength Hydropower Steel
by Zhongde Pan, Enmao Wang and Huibin Wu
Metals 2024, 14(7), 794; https://doi.org/10.3390/met14070794 - 8 Jul 2024
Viewed by 321
Abstract
Faced with the rapid development of large-scale pumped-storage power stations, the trade-off between the strength and toughness of hydropower steels in extreme environments has been limiting their application. The effects of Nb micro-alloying and direct quenching and tempering processes on the strengthening–toughening mechanism [...] Read more.
Faced with the rapid development of large-scale pumped-storage power stations, the trade-off between the strength and toughness of hydropower steels in extreme environments has been limiting their application. The effects of Nb micro-alloying and direct quenching and tempering processes on the strengthening–toughening mechanism of 1000 MPa grade high-strength hydropower steel are studied in this paper, and the precipitation behavior of Nb is discussed. The results showed that only the 0.025Nb steel using the DQT process achieved a cryogenic impact energy of more than 100 J at −60 °C. Under the DQT process, a large number of deformation bands and dislocations were retained, refining the prior austenite grains and providing more nucleation sites for the precipitation of NbC during the cooling process. The DQT process has a more obvious local strain concentration, mainly focusing on the refined lath boundary, which indicates that the refinement of the microstructure also promotes the stacking of dislocations. The improvement in fine grain strengthening and dislocation strengthening by the DQT process jointly led to an increase in strength, resulting in a better combination of strength and toughness. Full article
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21 pages, 7203 KiB  
Article
Experimental Investigations of the AC-Conductivity in NaTaO3 Ceramic Materials Doped with Cu and Al Metal Ions
by Iosif Malaescu, Paula Sfirloaga and Catalin Nicolae Marin
Metals 2024, 14(7), 793; https://doi.org/10.3390/met14070793 - 8 Jul 2024
Viewed by 425
Abstract
Two ceramic samples of sodium tantalate (NaTaO3), doped with metal ions of copper (Cu; sample S1) or aluminum (Al; sample S2), were obtained by the sol-gel method. Complex impedance measurements in the frequency range (200 Hz–2 MHz) and at temperatures between [...] Read more.
Two ceramic samples of sodium tantalate (NaTaO3), doped with metal ions of copper (Cu; sample S1) or aluminum (Al; sample S2), were obtained by the sol-gel method. Complex impedance measurements in the frequency range (200 Hz–2 MHz) and at temperatures between 30 °C and 90 °C allowed identification of a transition temperature from semiconductor-type behavior to conductor-type behavior for each sample (52 °C for sample S1 and 54 °C for sample S2). In the temperature range with semiconductor behavior, the activation energy of each sample was determined. Based on the Mott’s variable-range hopping (VRH) model, the density of localized states at the Fermi level, N(EF), the hopping distance (R) and the hopping energy (W) were determined, for the first time, on NaTaO3 samples doped with Cu or Al metal ions. The increase in N(EF) of sample S2 compared to N(EF) of sample S1 was explained by the decrease in the hopping distance of charge carriers in sample S2 compared to that in sample S1. Additionally, using the correlated barrier hopping (CBH) model, the energy band gap (Wm) and the hopping (crossover) frequency (ωh) at various temperatures were determined. Knowledge of these electrical properties is very important for explaining the electrical conduction mechanisms in metal ion-doped compounds, with perovskite structure being of interest for the use of these materials in the conversion of thermoelectric energy, photocatalytic applications, electronics or other applications. Full article
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18 pages, 7831 KiB  
Article
New Insights into the Ingot Breakdown Mechanism of Near-β Titanium Alloy: An Orientation-Driven Perspective
by Xianghong Liu, Tao Wang, Xiaolong Ren, Jie Fu, Liang Cheng, Bin Zhu and Kaixuan Wang
Metals 2024, 14(7), 792; https://doi.org/10.3390/met14070792 - 7 Jul 2024
Viewed by 420
Abstract
The ingot breakdown behavior of a typical near-β titanium alloy, Ti-55511, was investigated by various multi-pass upsetting processes. Particular emphasis was placed on the breakdown mechanism of the ultra-large β grains. The results showed that the upsetting far above the β-transus yielded uniform [...] Read more.
The ingot breakdown behavior of a typical near-β titanium alloy, Ti-55511, was investigated by various multi-pass upsetting processes. Particular emphasis was placed on the breakdown mechanism of the ultra-large β grains. The results showed that the upsetting far above the β-transus yielded uniform and refined macrostructure with relatively coarse grain size. In contrast, subtransus deformation within the (α + β) dual-phase field caused severe strain localization and macroscale shear bands. It was found that the static recrystallization during the post-deformation annealing was determined by the preferential grain orientations, which were closely related to the processing conditions. During β-working, the stable <001>-oriented grains were predominant and fragmentized mainly via a so-called “low-angle grain boundary merging” mechanism, even under a fairly low deformation. However, the vast <001> grain area was unbeneficial for microstructural conversion since it provided minor nucleation sites for the subsequent annealing. In contrast, the α/β-working produced the majority <111>-orientated grains, which were strongly inclined to strain localization. Highly misoriented deformation/shear bands were massively produced within the <111> grains, providing abundant nucleation sites for static recrystallization and, hence, were favorable for microstructural refinement. Furthermore, the intrinsic causes for deformation nonuniformity were discussed in detail, as well as the competition between microstructural homogeneity and refinement. Full article
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13 pages, 2957 KiB  
Article
Effect of Annealing Temperature on Microstructure and Properties of DH Steel and Optimization of Hole Expansion Property
by Yuhuan Yang, Xiaoyue Ma, Hongzhou Lu and Zhengzhi Zhao
Metals 2024, 14(7), 791; https://doi.org/10.3390/met14070791 - 7 Jul 2024
Viewed by 330
Abstract
In this article, DH steel containing Nb and Nb-Cu above 1000 MPa was designed, and its phase transformation law was analyzed through thermal expansion tests. The influence of annealing temperature on the microstructure and properties of DH steel was studied using a continuous [...] Read more.
In this article, DH steel containing Nb and Nb-Cu above 1000 MPa was designed, and its phase transformation law was analyzed through thermal expansion tests. The influence of annealing temperature on the microstructure and properties of DH steel was studied using a continuous annealing simulation testing machine, SEM, and tensile testing machine. The results showed that under a continuous annealing process, the test steel is composed of ferrite, martensite, a small amount of bainite, and residual austenite. The tensile strength decreases with the increase in annealing temperature, Cu element is dissolved in the matrix which produces solid solution strengthening and results in an increase in the strength of Cu-bearing test steel. Finally, 1180 MPa grade DH steel with excellent comprehensive properties was obtained at an annealing temperature of 840 °C and an overaging temperature of 340 °C. The expansion performance of the experimental steel was studied and optimized. Under the step heating annealing process, the experimental steel is composed of tempered martensite, ferrite, and residual austenite, with smaller differences in hardness between different phases, lower average dislocation density, and better expansion performance. Cu-bearing DH steel achieved an excellent match of strength and plasticity of 1289 MPa × 19.8%, with the hole expansion rate of 21.9% and the loss rate of hole expansion rate of 10%. Full article
(This article belongs to the Special Issue Metal Rolling and Heat Treatment Processing)
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12 pages, 7480 KiB  
Article
Ni-Doped Activated Carbon from Invasive Plants as a Potential Catalyst
by Kamil Dudek, Konrad Wojtaszek and Piotr Żabiński
Metals 2024, 14(7), 790; https://doi.org/10.3390/met14070790 - 6 Jul 2024
Viewed by 395
Abstract
In this study we synthesized and characterized Ni/AC (Activated Carbon) systems. AC was obtained through pyrolysis of golden rod’s dried biomass. Ni nanoparticles were deposited on AC’s surface using a wet impregnation method from a nickel nitrate solution. SEM, MP-AES and DSC-TGA techniques [...] Read more.
In this study we synthesized and characterized Ni/AC (Activated Carbon) systems. AC was obtained through pyrolysis of golden rod’s dried biomass. Ni nanoparticles were deposited on AC’s surface using a wet impregnation method from a nickel nitrate solution. SEM, MP-AES and DSC-TGA techniques were used for surficial and structural characterization, while ash content was made to check mineral ingredients input. The DSC-TGA study revealed that all carbons show good thermal stability up to 900 °C, which is far above operating temperatures in the methanation process. For all three carbons the BET isotherms were made as well. They show that in most cases the carbon’s surface is well developed and can adsorb decent amounts of metal. MP-AES helped to evaluate the efficiency of the impregnation process, which reached 76 mg of Ni per 1 g of carbon. The SEM-EDS study showed good distribution of Ni nanoparticles across AC’s surface. We also made a comparison of our systems to similar materials from other works. Full article
(This article belongs to the Special Issue Advances in Nanostructured Metallic Materials)
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15 pages, 3039 KiB  
Article
A First-Principles Study of the Structural, Elastic, and Mechanical Characteristics of Mg2Ni Subjected to Pressure Conditions
by Chuncai Xiao, Lei Liu, Shihuan Liu, Zhangli Lai, Yuxin Liu, Xianshi Zeng and Luliang Liao
Metals 2024, 14(7), 789; https://doi.org/10.3390/met14070789 - 5 Jul 2024
Viewed by 284
Abstract
This study employs first-principles calculations to examine structural, elastic, and mechanistic relationships of Mg2Ni alloys under varying conditions of pressure. The investigation encompasses Young’s modulus, bulk modulus, shear modulus, Poisson’s ratio, and anisotropy index, as well as sound velocity, Debye temperature, [...] Read more.
This study employs first-principles calculations to examine structural, elastic, and mechanistic relationships of Mg2Ni alloys under varying conditions of pressure. The investigation encompasses Young’s modulus, bulk modulus, shear modulus, Poisson’s ratio, and anisotropy index, as well as sound velocity, Debye temperature, and related properties. Our findings indicate that the lattice parameters of Mg2Ni in its ground state are in agreement with values obtained experimentally and from the literature, confirming the reliability of the calculated results. Furthermore, a gradual decrease in the values of the lattice parameters a/a0 and c/c0 is observed with increasing pressure. Specifically, the values for C13 and C33 decrease at a hydrostatic pressure of 5 GPa, while C11 and C13 increase when the external hydrostatic pressure exceeds 5 GPa. All other elastic constants exhibit a consistent increasing trend with increasing pressure between 0 and 30 GPa, with C11 and C12 increasing at a faster rate than C44 and C66. In the 0–30 GPa pressure range, Mg2Ni satisfies the mechanical stability criterion, indicating its stable existence under these conditions. Additionally, the Poisson’s ratio of Mg2Ni consistently exceeds 0.26 over a range of pressures from 0 to 30 GPa, signifying ductility and demonstrating consistency with the value of B/G. The hardness of Mg2Ni increases within the pressure range of 0–5 GPa, but decreases above 5 GPa. Notably, the shear anisotropy of Mg2Ni exhibits greater significance than the compressive anisotropy, with its anisotropy intensifying under higher pressures. Both the sound anisotropy and the Debye temperature of Mg2Ni demonstrate an increasing trend with rising pressure. Full article
(This article belongs to the Special Issue Modeling, Simulation and Experimental Studies in Metal Forming)
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15 pages, 10628 KiB  
Article
High Strain Rate Deformation Behavior of Gradient Rolling AZ31 Alloys
by Yingjie Li, Hui Yu, Chao Liu, Yu Liu, Wei Yu, Yuling Xu, Binan Jiang, Kwangseon Shin and Fuxing Yin
Metals 2024, 14(7), 788; https://doi.org/10.3390/met14070788 - 5 Jul 2024
Viewed by 277
Abstract
A dynamic impact test was performed on as-rolled AZ31 alloys with gradient microstructure under various strains. The microstructural evolution and mechanical properties were systematically investigated. As the strain rate gradually increased, an increasing number of twins were formed, facilitating dynamic recrystallization (DRX), and [...] Read more.
A dynamic impact test was performed on as-rolled AZ31 alloys with gradient microstructure under various strains. The microstructural evolution and mechanical properties were systematically investigated. As the strain rate gradually increased, an increasing number of twins were formed, facilitating dynamic recrystallization (DRX), and the mechanical properties were also gradually improved. The microstructure became heterogeneous at higher strain rates, but the peak stress decreased. The impact process resulted in a significantly higher performance due to microstructural refinement, work hardening by dislocations, and precipitates. In addition, both the adiabatic shear band and the adjacent crack experienced a temperature rise that exceeded the recrystallization temperature of the alloys. This observation also explains the presence of ultrafine recrystallized grains within the adiabatic shear band and the appearance of molten metal around the crack. Full article
(This article belongs to the Special Issue Preparation and Processing Technology of Advanced Magnesium Alloys)
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17 pages, 3917 KiB  
Article
Experimental Characterization and Phase-Field Damage Modeling of Ductile Fracture in AISI 316L
by Vladimir Dunić, Nenad Gubeljak, Miroslav Živković, Vladimir Milovanović, Darko Jagarinec and Nenad Djordjevic
Metals 2024, 14(7), 787; https://doi.org/10.3390/met14070787 - 5 Jul 2024
Viewed by 317
Abstract
(1) Modeling and characterization of ductile fracture in metals is still a challenging task in the field of computational mechanics. Experimental testing offers specific responses in the form of crack-mouth (CMOD) and crack-tip (CTOD) opening displacement related to applied force or crack growth. [...] Read more.
(1) Modeling and characterization of ductile fracture in metals is still a challenging task in the field of computational mechanics. Experimental testing offers specific responses in the form of crack-mouth (CMOD) and crack-tip (CTOD) opening displacement related to applied force or crack growth. The main aim of this paper is to develop a phase-field-based Finite Element Method (FEM) implementation for modeling of ductile fracture in stainless steel. (2) A Phase-Field Damage Model (PFDM) was coupled with von Mises plasticity and a work-densities-based criterion was employed, with a threshold to propose a new relationship between critical fracture energy and critical total strain value. In addition, the threshold value of potential internal energy—which controls damage evolution—is defined from the critical fracture energy. (3) The material properties of AISI 316L steel are determined by a uniaxial tensile test and the Compact Tension (CT) specimen crack growth test. The PFDM model is validated against the experimental results obtained in the fracture toughness characterization test, with the simulation results being within 8% of the experimental measurements. (4) The novel implementation offers the possibility for better control of the ductile behavior of metallic materials and damage initiation, evolution, and propagation. Full article
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15 pages, 3788 KiB  
Article
Influence of the Glycidyl Azide Polymer on the Energy Release of Aluminum Sub-Micron Particles under Ultrafast Heating Rates Stimulated by Electric Explosion and Solid Laser
by Yaru Li, Hui Ren and Shuo Liu
Metals 2024, 14(7), 786; https://doi.org/10.3390/met14070786 - 5 Jul 2024
Viewed by 336
Abstract
Glycidyl azide polymer (GAP)-coated sub-micron aluminum (sub-mAl@GAP) particles exhibit higher heat release than their uncoated counterparts under low heating rates. However, their application in explosives has been hindered due to a lack of understanding of their energy release characteristics under heating rates of [...] Read more.
Glycidyl azide polymer (GAP)-coated sub-micron aluminum (sub-mAl@GAP) particles exhibit higher heat release than their uncoated counterparts under low heating rates. However, their application in explosives has been hindered due to a lack of understanding of their energy release characteristics under heating rates of detonation levels. To address this problem, the energy release performances of sub-mAl@GAP particles under ultrafast heating rates stimulated by an electric explosion of wire and high-energy laser were studied. The results showed that the reaction of sub-mAl@GAP particles was more violent than that of an uncoated counterpart under an electric explosion stimulus. Additionally, the reaction time of the former was 0.4 ms shorter than that of the latter. In addition, the propagations of shock waves of the sub-mAl@GAP and sub-mAl were analyzed. The propagation distances of shock waves of the sub-mAl@GAP were all longer than those of sub-mAl under laser fluences of 0.5 J/cm2, 1.2 J/cm2, and 2.4 J/cm2. The distance difference gradually increased with the decrease in the laser fluence. Under a laser fluence of 0.5 J/cm2, the velocity and distance differences of the sub-mAl@GAP and sub-mAl were both the largest due to the energy contribution from the GAP. In conclusion, the fast decomposition rate of the GAP and its energy contribution would benefit the energy release of sub-mAl under ultrafast heating rates. Full article
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10 pages, 2368 KiB  
Article
Effect of Intermediate Annealing on Microstructure and Cold Rolling Hardness of AlFeMn Alloy
by Yanfeng Pan, Yifu Shen and Lingyong Cao
Metals 2024, 14(7), 785; https://doi.org/10.3390/met14070785 - 4 Jul 2024
Viewed by 390
Abstract
The microstructure and texture of an AlFeMn alloy were studied under different intermediate annealing processes, and the changes in microhardness during cold rolling were analyzed. After annealing at 420 °C with a slow heating rate, the alloy showed a high number of small [...] Read more.
The microstructure and texture of an AlFeMn alloy were studied under different intermediate annealing processes, and the changes in microhardness during cold rolling were analyzed. After annealing at 420 °C with a slow heating rate, the alloy showed a high number of small dispersed particles and recrystallization textures dominated by R texture, with deformation textures of 23.5%. Annealing at 610 °C with a rapid heating rate resulted in a significant decrease in the number of small-sized particles and an increase in recrystallization texture contents, with CubeND being the majority. The deformation texture contents decreased to 14.9%. The electrical conductivity of the 420 °C annealed sheet was higher than before annealing, whereas the sheet annealed at 610 °C showed a decrease in electrical conductivity after annealing. This indicated that annealing at 610 °C led to a higher degree of recrystallization and the development of Cube/CubeND due to the dissolution of dispersed particles. During the subsequent cold rolling process, the microhardness of both annealed sheets initially increased and then decreased. However, the microhardness of the 420 °C annealed sheet with varying cold rolling reductions consistently remained lower than that of the 610 °C annealed sheet, as was the cold rolling reduction corresponding to the peak microhardness. The results showed that the precipitation at 420 °C facilitated work softening, while the dissolution at 610 °C promoted work hardening. Full article
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16 pages, 10634 KiB  
Article
Glass—Mill Scale—Plastics Wastes Upcycling for Synthesis of Ferrosilicon Alloy at 1550 °C: Implication for Zero Wastes Practice
by Somyote Kongkarat, Sitichoke Amnuanpol and Praphaphan Wongsawan
Metals 2024, 14(7), 784; https://doi.org/10.3390/met14070784 - 4 Jul 2024
Viewed by 526
Abstract
Driven by the rising demand for glass, metals, and plastics in industrial and household sectors, there was a substantial increase in waste and by-products generated. This study presents a method for repurposing waste glass, mill scale, and plastics as raw materials for ferrosilicon [...] Read more.
Driven by the rising demand for glass, metals, and plastics in industrial and household sectors, there was a substantial increase in waste and by-products generated. This study presents a method for repurposing waste glass, mill scale, and plastics as raw materials for ferrosilicon alloy production. This process entails reducing SiO2 and Fe2O3 using carbon derived from polystyrene/polypropylene mixtures. The glass, scale, and carbon powders were blended to achieve a C/O molar ratio of 1 (Blends A to F). The thoroughly mixed samples were then shaped into pellets and subsequently heated at 1550 °C in a tube furnace for 60 min. Ferrosilicon was successfully synthesized, with the reaction generating numerous metal droplets along with a slag layer in the crucible. The metallic yield for Blends A to F ranged from 16.65 wt% to 21.39 wt%, with the highest yield observed in Blend D. The bulk metal primarily consists of the FeSi phase, with Blend D exhibiting the highest Si concentration of 13.51 wt% and the highest hardness of 649.55 HV. Mechanism steps for ferrosilicon formation may vary with carbon dissolution rates. This work supports fossil fuel reduction and carbon neutrality, benefiting zero wastes practice and promoting sustainable material processing. Full article
(This article belongs to the Special Issue Metal Recovery and Separation from Scraps and Wastes)
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