We investigated the reaction kinetics and initial chemical conditions in the production of silicon alloys, employing aluminum as the reductant for calcium silicate slag, to enhance process economics and scalability to industrial levels. The apparent kinetics and transient chemical conditions were studied by immersing solid aluminum into molten slag, allowing the reaction to proceed for varying durations without external agitation, before quenching the reaction for chemical and microscopic analyses of the resulting silicon alloy and slag. The majority of the conversion was observed within the first 15 s at 1650 °C, driven by significant chemical interactions and interfacial turbulence introduced upon aluminum immersion. For Al-SiO2 stoichiometries ranging from 0.5 to 1.2, the slag phase reaction conformed to first-order kinetics during the initial two minutes, when it approached equilibrium. The mass transfer coefficients for Al2O3 were estimated at 1–2 × 10−4 m/s, comparable to those for SiO2 and CaO. A constant mass transfer coefficient could not be established for stoichiometries of 1.6 and 2, as these deviated from the standard slag mass transfer relationship and did not adhere to established relationships. Despite near-complete reactions, alloy–slag mixing was extensive, decreasing with lower stoichiometry values.
{"title":"Aluminothermic Reduction Kinetics of Calcium Silicate Slag for Silicon Alloy Production","authors":"Harald Philipson, Maria Wallin, K. Einarsrud","doi":"10.3390/met14060604","DOIUrl":"https://doi.org/10.3390/met14060604","url":null,"abstract":"We investigated the reaction kinetics and initial chemical conditions in the production of silicon alloys, employing aluminum as the reductant for calcium silicate slag, to enhance process economics and scalability to industrial levels. The apparent kinetics and transient chemical conditions were studied by immersing solid aluminum into molten slag, allowing the reaction to proceed for varying durations without external agitation, before quenching the reaction for chemical and microscopic analyses of the resulting silicon alloy and slag. The majority of the conversion was observed within the first 15 s at 1650 °C, driven by significant chemical interactions and interfacial turbulence introduced upon aluminum immersion. For Al-SiO2 stoichiometries ranging from 0.5 to 1.2, the slag phase reaction conformed to first-order kinetics during the initial two minutes, when it approached equilibrium. The mass transfer coefficients for Al2O3 were estimated at 1–2 × 10−4 m/s, comparable to those for SiO2 and CaO. A constant mass transfer coefficient could not be established for stoichiometries of 1.6 and 2, as these deviated from the standard slag mass transfer relationship and did not adhere to established relationships. Despite near-complete reactions, alloy–slag mixing was extensive, decreasing with lower stoichiometry values.","PeriodicalId":510812,"journal":{"name":"Metals","volume":"17 14","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141118319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study focuses on the microstructures and soft-magnetic properties of the Al1.5Fe3Co3Cr1 multi-principal-element alloy (MPEA) in different states. The MPEA was prepared using arc melting and suction-casting, followed by various heat treatments. The crystal structures were analyzed using X-ray diffraction (XRD), while the microstructures were characterized by means of transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results reveal that the MPEA consists mainly of coherent body-centered cubic (BCC) and B2 phases, with a moderate lattice misfit (ε = 0.14~0.21%) between them. The homogenized alloy shows the presence of coarse equiaxed grains and micro-scale cells, and it has good soft-magnetic properties with MS = 127 emu/g and HC = 143.3 A/m (1.8 Oe). The thermal stability of the alloy is found to be optimal after aging at 873 K, as there are no significant changes in microstructures and soft-magnetic properties. However, when the aging temperature increases to 973 K, the BCC nanoprecipitates are coarsened, leading to a decrease in the soft-magnetic properties.
本研究的重点是 Al1.5Fe3Co3Cr1 多主元素合金（MPEA）在不同状态下的微观结构和软磁特性。MPEA 采用电弧熔炼和吸铸工艺制备，然后经过各种热处理。利用 X 射线衍射（XRD）分析了晶体结构，并通过透射电子显微镜（TEM）和扫描电子显微镜（SEM）对微观结构进行了表征。结果表明，MPEA 主要由相干的体心立方（BCC）相和 B2 相组成，它们之间存在适度的晶格错配（ε = 0.14~0.21%）。均质合金中存在粗大的等轴晶粒和微尺度晶胞，具有良好的软磁特性，MS = 127 emu/g，HC = 143.3 A/m (1.8 Oe)。在 873 K 温度下老化后，合金的热稳定性达到最佳状态，微观结构和软磁特性没有发生显著变化。然而，当老化温度升高到 973 K 时，BCC 纳米沉淀物变得粗糙，导致软磁特性下降。
{"title":"Microstructure Dependence of Magnetic Properties for Al1.5Fe3Co3Cr1 Multi-Principal-Element Alloy","authors":"Shaoheng Sun, Yaxia Qiao, Hao Zhang, Dejun Tu, Guojun Wang, Zhenhua Wang, Qing Wang","doi":"10.3390/met14060608","DOIUrl":"https://doi.org/10.3390/met14060608","url":null,"abstract":"This study focuses on the microstructures and soft-magnetic properties of the Al1.5Fe3Co3Cr1 multi-principal-element alloy (MPEA) in different states. The MPEA was prepared using arc melting and suction-casting, followed by various heat treatments. The crystal structures were analyzed using X-ray diffraction (XRD), while the microstructures were characterized by means of transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results reveal that the MPEA consists mainly of coherent body-centered cubic (BCC) and B2 phases, with a moderate lattice misfit (ε = 0.14~0.21%) between them. The homogenized alloy shows the presence of coarse equiaxed grains and micro-scale cells, and it has good soft-magnetic properties with MS = 127 emu/g and HC = 143.3 A/m (1.8 Oe). The thermal stability of the alloy is found to be optimal after aging at 873 K, as there are no significant changes in microstructures and soft-magnetic properties. However, when the aging temperature increases to 973 K, the BCC nanoprecipitates are coarsened, leading to a decrease in the soft-magnetic properties.","PeriodicalId":510812,"journal":{"name":"Metals","volume":"13 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141118593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yue-Yue Tian, Bo-Yuan Ning, Hui-Fen Zhang, Xi-Jing Ning
Body−centered cubic bismuth (Bi) is considered to be an enticing pressure marker, and, therefore, it is highly desirable to command its accurate equation of state (EOS). However, significant discrepancies are noted among the previous experimental EOSs. In the present work, an EOS of up to 300 GPa is theoretically obtained by solving the partition function via a direct integral approach (DIA). The calculated results nearly reproduce the hydrostatic experimental measurements below 75 GPa, and the deviations from the measurements gradually become larger with increasing pressure. Based on the ensemble theory of equilibrium state, the DIA works with high precision particularly in high−pressure conditions, so the hydrostatic EOS presented in this work is expected to be a reliable pressure standard.
体心立方铋（Bi）被认为是一种诱人的压力标记，因此，人们非常希望掌握其精确的状态方程（EOS）。然而，以往的实验 EOS 存在很大差异。在本研究中，通过直接积分法（DIA）求解分区函数，从理论上获得了高达 300 GPa 的 EOS。计算结果几乎再现了 75 GPa 以下的流体静力学实验测量值，并且随着压力的增加，与测量值的偏差逐渐变大。基于平衡态的集合理论，DIA 的工作精度很高，尤其是在高压条件下，因此这项工作中提出的静力学 EOS 预计将成为可靠的压力标准。
{"title":"Hydrostatic Equation of State of bcc Bi by Directly Solving the Partition Function","authors":"Yue-Yue Tian, Bo-Yuan Ning, Hui-Fen Zhang, Xi-Jing Ning","doi":"10.3390/met14050601","DOIUrl":"https://doi.org/10.3390/met14050601","url":null,"abstract":"Body−centered cubic bismuth (Bi) is considered to be an enticing pressure marker, and, therefore, it is highly desirable to command its accurate equation of state (EOS). However, significant discrepancies are noted among the previous experimental EOSs. In the present work, an EOS of up to 300 GPa is theoretically obtained by solving the partition function via a direct integral approach (DIA). The calculated results nearly reproduce the hydrostatic experimental measurements below 75 GPa, and the deviations from the measurements gradually become larger with increasing pressure. Based on the ensemble theory of equilibrium state, the DIA works with high precision particularly in high−pressure conditions, so the hydrostatic EOS presented in this work is expected to be a reliable pressure standard.","PeriodicalId":510812,"journal":{"name":"Metals","volume":"11 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141119807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Igor J. U. V. Pereira, Henrique C. S. Coelho, Cláudio G. Santos, E. Brocchi, Rodrigo F. M. Souza, Víctor A. A. Oliveira
A sample of goethite iron ore sinter feed (G_SF) was employed as a raw material in a sintering bed. This sample partially replaced hematite sinter feed (H_SF), which is currently used as raw material in a sintering plant in the state of Minas Gerais, Brazil. This substitution did not adversely affect the chemical and metallurgical proprieties of the sinter mix product, provided that the utilization of G_SF was kept below 30% in weight. Despite the higher proportion of fines in G_SF, the presence of argillaceous minerals in the sample led to an improvement in the granulation index (GI) of the sinter mix product. The GI value increased from 68.4 to 82.7% for the experiments conducted without the presence of goethite ore and with 40% of goethite ore in the sintering mix, respectively. Consequently, the qualities of both the process and the produced sinter product were not compromised. The raw materials and the various sinters produced were characterized through X-ray fluorescence (XRF) and X-ray diffraction (XRD), as well as thermal gravimetric analysis (TGA). The XRD results were used to perform a quantitative assessment of the mineral phase using the Rietveld method (RM). This technique allowed for the determination of goethite content in the studied sample, which was 35.5%. Finally, the incorporation of G_SF in the sintering bed led to a 20% reduction in the cost of raw materials.
{"title":"Batch Sintering of FeO·OH and Fe2O3 Blends: Chemical and Metallurgical Characterization","authors":"Igor J. U. V. Pereira, Henrique C. S. Coelho, Cláudio G. Santos, E. Brocchi, Rodrigo F. M. Souza, Víctor A. A. Oliveira","doi":"10.3390/met14050598","DOIUrl":"https://doi.org/10.3390/met14050598","url":null,"abstract":"A sample of goethite iron ore sinter feed (G_SF) was employed as a raw material in a sintering bed. This sample partially replaced hematite sinter feed (H_SF), which is currently used as raw material in a sintering plant in the state of Minas Gerais, Brazil. This substitution did not adversely affect the chemical and metallurgical proprieties of the sinter mix product, provided that the utilization of G_SF was kept below 30% in weight. Despite the higher proportion of fines in G_SF, the presence of argillaceous minerals in the sample led to an improvement in the granulation index (GI) of the sinter mix product. The GI value increased from 68.4 to 82.7% for the experiments conducted without the presence of goethite ore and with 40% of goethite ore in the sintering mix, respectively. Consequently, the qualities of both the process and the produced sinter product were not compromised. The raw materials and the various sinters produced were characterized through X-ray fluorescence (XRF) and X-ray diffraction (XRD), as well as thermal gravimetric analysis (TGA). The XRD results were used to perform a quantitative assessment of the mineral phase using the Rietveld method (RM). This technique allowed for the determination of goethite content in the studied sample, which was 35.5%. Finally, the incorporation of G_SF in the sintering bed led to a 20% reduction in the cost of raw materials.","PeriodicalId":510812,"journal":{"name":"Metals","volume":"79 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141123043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qingsong Li, Yang Tian, Lingxin Kong, Bin Yang, Baoqiang Xu, Wen-long Jiang, Lipeng Wang
The Ag–Cu–Sb system is a key component of lead anode slime and boasts an exceptionally high economic recovery value. In this work, six models, including the Molecular Interaction Volume Model (MIVM), Modified Molecular Interaction Volume Model (M-MIVM), Wilson equation, Miedema model, Regular Solution Model (RSE) and Sub-Regular Solution Model (SRSE), are used to calculate the predicted values of the activity and its deviations with experimental data for binary alloys in the Ag–Cu–Sb system for the first time. The result reveals that the overall means of the average relative deviation and average standard deviation of the M-MIVM are 0.01501 and 3.97278%, respectively, which are about two to six times smaller than those of the other five models, indicating the stability and reliability of the M-MIVM. In the meantime, the predicted data of the Cu–Ag binary alloy at 1423 K, Sb–Ag binary alloy at 1250 K and Sb–Cu binary alloy at 1375 K calculated from the M-MIVM are more reliable and pass the Herington test. Then, the separation coefficient–composition (β–x), temperature–composition (T–x–y) and pressure–composition (P–x–y) of the Cu–Ag, Sb–Ag and Sb–Cu binary alloys are plotted based on the M-MIVM and vacuum theories, showing that the Cu–Ag binary alloy is relatively difficult to separate and that high temperatures or high copper contents are detrimental to obtaining high-purity silver. Meanwhile, theoretical data of the T–x–y diagram are consistent with the available experimental data. These results can guide vacuum separation experiments and industrial production concerning Ag–Cu, Ag–Sb and Cu–Sb binary alloys.
{"title":"Activity Calculation and Vacuum Separation Theoretical Research concerning Ag–Cu, Ag–Sb and Cu–Sb Binary Alloys","authors":"Qingsong Li, Yang Tian, Lingxin Kong, Bin Yang, Baoqiang Xu, Wen-long Jiang, Lipeng Wang","doi":"10.3390/met14050603","DOIUrl":"https://doi.org/10.3390/met14050603","url":null,"abstract":"The Ag–Cu–Sb system is a key component of lead anode slime and boasts an exceptionally high economic recovery value. In this work, six models, including the Molecular Interaction Volume Model (MIVM), Modified Molecular Interaction Volume Model (M-MIVM), Wilson equation, Miedema model, Regular Solution Model (RSE) and Sub-Regular Solution Model (SRSE), are used to calculate the predicted values of the activity and its deviations with experimental data for binary alloys in the Ag–Cu–Sb system for the first time. The result reveals that the overall means of the average relative deviation and average standard deviation of the M-MIVM are 0.01501 and 3.97278%, respectively, which are about two to six times smaller than those of the other five models, indicating the stability and reliability of the M-MIVM. In the meantime, the predicted data of the Cu–Ag binary alloy at 1423 K, Sb–Ag binary alloy at 1250 K and Sb–Cu binary alloy at 1375 K calculated from the M-MIVM are more reliable and pass the Herington test. Then, the separation coefficient–composition (β–x), temperature–composition (T–x–y) and pressure–composition (P–x–y) of the Cu–Ag, Sb–Ag and Sb–Cu binary alloys are plotted based on the M-MIVM and vacuum theories, showing that the Cu–Ag binary alloy is relatively difficult to separate and that high temperatures or high copper contents are detrimental to obtaining high-purity silver. Meanwhile, theoretical data of the T–x–y diagram are consistent with the available experimental data. These results can guide vacuum separation experiments and industrial production concerning Ag–Cu, Ag–Sb and Cu–Sb binary alloys.","PeriodicalId":510812,"journal":{"name":"Metals","volume":"1 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141120368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bin Liu, Chenglu Liu, Xuewen Li, Hao Wu, Kesong Miao, He Wu, Rengeng Li
In this article, we subjected the Ti60 alloy to solid-solution treatment at 1020 °C and aging treatment at 600 °C, respectively, achieving a bimodal microstructure. The microstructures obtained after aging treatment showed no significant difference in the primary α-phase content, size, and width of the lamellar α phase. This suggests that the final microstructure morphology is primarily determined by the solid-solution temperature, with the aging process exerting less pronounced effects on microstructural alterations. Furthermore, we investigated the effect of solid-solution and aging treatment on the crystallographic orientation evolution of the secondary α phase (αs) in the near-α titanium alloy Ti60. The αs phase displays a random orientation in solid-solution treatment sample, while it demonstrated a preferential {0 1 −1 0} orientation after aging treatment. This interesting phenomenon is attributed to the enhanced variant selection resulting from the dissolution of variant near 60° and 90° during aging. Furthermore, the αs with {0 1 −1 0} orientation nucleated at the grain boundary and coalesced into larger αs lath with increasing aging time, further contributing to the αs {0 1 −1 0} texture.
{"title":"Aging Treatment Induces the Preferential Crystallographic Orientation of αs in the Near-α Titanium Alloy Ti60","authors":"Bin Liu, Chenglu Liu, Xuewen Li, Hao Wu, Kesong Miao, He Wu, Rengeng Li","doi":"10.3390/met14050602","DOIUrl":"https://doi.org/10.3390/met14050602","url":null,"abstract":"In this article, we subjected the Ti60 alloy to solid-solution treatment at 1020 °C and aging treatment at 600 °C, respectively, achieving a bimodal microstructure. The microstructures obtained after aging treatment showed no significant difference in the primary α-phase content, size, and width of the lamellar α phase. This suggests that the final microstructure morphology is primarily determined by the solid-solution temperature, with the aging process exerting less pronounced effects on microstructural alterations. Furthermore, we investigated the effect of solid-solution and aging treatment on the crystallographic orientation evolution of the secondary α phase (αs) in the near-α titanium alloy Ti60. The αs phase displays a random orientation in solid-solution treatment sample, while it demonstrated a preferential {0 1 −1 0} orientation after aging treatment. This interesting phenomenon is attributed to the enhanced variant selection resulting from the dissolution of variant near 60° and 90° during aging. Furthermore, the αs with {0 1 −1 0} orientation nucleated at the grain boundary and coalesced into larger αs lath with increasing aging time, further contributing to the αs {0 1 −1 0} texture.","PeriodicalId":510812,"journal":{"name":"Metals","volume":"36 20","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141120399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study explored the impact of Hot Forming–Quenching (HFQ) and heat treatment processes on the mechanical properties of AA6016 sheets. The experimental findings demonstrated that at high-temperature pre-straining (HT-PS) of 15%, the strength performance of the AA6016 sheet exhibited enhancement, with a progressive increase in both the heat treatment temperature and duration. Conversely, under HT-PS conditions of 3% and 7%, the heat treatment process exhibited a relatively modest impact on the mechanical properties of the AA6016 sheet. Differential scanning calorimetry (DSC) was employed to understand the influence of different process conditions on the precipitated phases. By comparing the precipitation peaks of the β″ phase at HT-PS of 3% and 15%, it was observed that the precipitation peak of the β″ phase decreased with an increase in HT-PS. This indicated that HT-PS promoted the precipitation of the β″ phase. In order to forecast the mechanical performance of the AA6016 sheets after applying various pre-straining and heat treatment parameters, two models were used: a backpropagation (BP) neural network and a genetic algorithm (GA)-BP neural network. These models were evaluated for their fitting and predictive capabilities. The research findings demonstrated that the GA-BP neural network model exhibited superior fitting and predictive accuracy compared to the BP neural network model.
{"title":"The Effect of Hot Forming–Quenching and Heat Treatment Processes on the Mechanical Properties of AA6016 Aluminum Alloy Sheets","authors":"Jiahong Lu, Baitong Liu, Shiyao Huang, Zuguo Bao, Yutong Yang, Xilin Li, Zhenfei Zhan, Qing Liu","doi":"10.3390/met14050599","DOIUrl":"https://doi.org/10.3390/met14050599","url":null,"abstract":"This study explored the impact of Hot Forming–Quenching (HFQ) and heat treatment processes on the mechanical properties of AA6016 sheets. The experimental findings demonstrated that at high-temperature pre-straining (HT-PS) of 15%, the strength performance of the AA6016 sheet exhibited enhancement, with a progressive increase in both the heat treatment temperature and duration. Conversely, under HT-PS conditions of 3% and 7%, the heat treatment process exhibited a relatively modest impact on the mechanical properties of the AA6016 sheet. Differential scanning calorimetry (DSC) was employed to understand the influence of different process conditions on the precipitated phases. By comparing the precipitation peaks of the β″ phase at HT-PS of 3% and 15%, it was observed that the precipitation peak of the β″ phase decreased with an increase in HT-PS. This indicated that HT-PS promoted the precipitation of the β″ phase. In order to forecast the mechanical performance of the AA6016 sheets after applying various pre-straining and heat treatment parameters, two models were used: a backpropagation (BP) neural network and a genetic algorithm (GA)-BP neural network. These models were evaluated for their fitting and predictive capabilities. The research findings demonstrated that the GA-BP neural network model exhibited superior fitting and predictive accuracy compared to the BP neural network model.","PeriodicalId":510812,"journal":{"name":"Metals","volume":"85 14","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141121073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Quan Gao, Rengeng Li, Hao Wu, Kesong Miao, He Wu, Chenglu Liu, Xuewen Li
The mechanical properties of a fine-grained (FG) Ti-6Al-4V extra-low interstitial (ELI) alloy were investigated by tensile tests at 298 K and 77 K. The experimental results indicated that, at 77 K, the alloy exhibits a small uniform elongation of 2.65%, but has a fracture elongation of 19.2%, showing superior post-necking elongation. At 298 K, the alloy displays a single dislocation slipping, β→α″ phase transformation occurred, and 6.35% uniform elongation was obtained, whereas the coupling of dislocation slipping and twinning deformation behaviors dominated at 77 K. The limited uniform elongation is attributed to the absence of martensite phase transformation at 77 K, whereas the decent fracture elongation is ascribed to the resistance offered by twinning against plastic instability.
通过在 298 K 和 77 K 下进行拉伸试验，研究了细晶粒（FG）Ti-6Al-4V 超低间隙（ELI）合金的力学性能。实验结果表明，在 77 K 下，合金的均匀伸长率较小，仅为 2.65%，但断裂伸长率高达 19.2%，显示出优异的颈后伸长率。在 298 K 时，合金显示出单一的位错滑动，发生了 β→α″ 相变，获得了 6.35% 的均匀伸长率，而在 77 K 时，位错滑动和孪晶变形行为的耦合占主导地位。
{"title":"Revealing the Superior Post-Necking Elongation in the Fine-Grained Ti-6Al-4V ELI at Cryogenic Temperature","authors":"Quan Gao, Rengeng Li, Hao Wu, Kesong Miao, He Wu, Chenglu Liu, Xuewen Li","doi":"10.3390/met14050600","DOIUrl":"https://doi.org/10.3390/met14050600","url":null,"abstract":"The mechanical properties of a fine-grained (FG) Ti-6Al-4V extra-low interstitial (ELI) alloy were investigated by tensile tests at 298 K and 77 K. The experimental results indicated that, at 77 K, the alloy exhibits a small uniform elongation of 2.65%, but has a fracture elongation of 19.2%, showing superior post-necking elongation. At 298 K, the alloy displays a single dislocation slipping, β→α″ phase transformation occurred, and 6.35% uniform elongation was obtained, whereas the coupling of dislocation slipping and twinning deformation behaviors dominated at 77 K. The limited uniform elongation is attributed to the absence of martensite phase transformation at 77 K, whereas the decent fracture elongation is ascribed to the resistance offered by twinning against plastic instability.","PeriodicalId":510812,"journal":{"name":"Metals","volume":"38 20","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141122222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The effect of pre-weld heat treatment on the microstructure and low-temperature impact toughness of the coarse-grained heat-affected zone (CGHAZ) after simulated welding was systematically investigated through the utilization of scanning electron microscopy (SEM) and electron back-scattering diffraction (EBSD). The Charpy impact test validated the presence of an optimal pre-weld heat treatment condition, resulting in the highest impact toughness observed in the CGHAZ. Three temperatures for pre-weld heat treatment (690, 720 and 750 °C) were used to obtain three different matrices (Steel 1, Steel 2, Steel 3) for simulated welding. The optimal pre-weld heat treatment is 720 °C for 15 min followed by water quench. Microstructure characterization showed that there is an evident microstructure comprising bainite (B) in Steel 1 and Steel 2 after pre-weld heat treatment, while the addition of martensite (M) with the pre-weld heat treatment temperature exceeds Ac1 by almost 60 °C (Steel 3). These differences in microstructures obtained from pre-weld heat treatment influence the refinement of high-temperature austenite during subsequent simulated welding reheating processes, resulting in distinct microstructural characteristics in the CGHAZ. After the optimal pre-weld heat treatment, Steel 2 subjected to single-pass welding thermal simulation demonstrates a refined microstructure characterized by a high density of high-angle grain boundaries (HAGBs) within the CGHAZ, particularly evident in block boundaries. These boundaries effectively prevent the propagation of brittle cracks, thereby enhancing the impact toughness.
{"title":"Effect of Pre-Weld Heat Treatment on the Microstructure and Properties of Coarse-Grained Heat-Affected Zone of a Wind Power Steel after Simulated Welding","authors":"Zhixing Wang, Xuelin Wang, Chengjia Shang","doi":"10.3390/met14050587","DOIUrl":"https://doi.org/10.3390/met14050587","url":null,"abstract":"The effect of pre-weld heat treatment on the microstructure and low-temperature impact toughness of the coarse-grained heat-affected zone (CGHAZ) after simulated welding was systematically investigated through the utilization of scanning electron microscopy (SEM) and electron back-scattering diffraction (EBSD). The Charpy impact test validated the presence of an optimal pre-weld heat treatment condition, resulting in the highest impact toughness observed in the CGHAZ. Three temperatures for pre-weld heat treatment (690, 720 and 750 °C) were used to obtain three different matrices (Steel 1, Steel 2, Steel 3) for simulated welding. The optimal pre-weld heat treatment is 720 °C for 15 min followed by water quench. Microstructure characterization showed that there is an evident microstructure comprising bainite (B) in Steel 1 and Steel 2 after pre-weld heat treatment, while the addition of martensite (M) with the pre-weld heat treatment temperature exceeds Ac1 by almost 60 °C (Steel 3). These differences in microstructures obtained from pre-weld heat treatment influence the refinement of high-temperature austenite during subsequent simulated welding reheating processes, resulting in distinct microstructural characteristics in the CGHAZ. After the optimal pre-weld heat treatment, Steel 2 subjected to single-pass welding thermal simulation demonstrates a refined microstructure characterized by a high density of high-angle grain boundaries (HAGBs) within the CGHAZ, particularly evident in block boundaries. These boundaries effectively prevent the propagation of brittle cracks, thereby enhancing the impact toughness.","PeriodicalId":510812,"journal":{"name":"Metals","volume":"4 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140962251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Jürgensen, Andreas Frehn, Klaus Ohla, Sandra Stolz, Michael Pohl
Hydrogen embrittlement (HE) poses the risk of premature failure for many metals, especially high-strength steels. Due to the utilization of hydrogen as an environmentally friendly energy source, efforts are made to improve the resistance to HE at elevated pressures and temperatures. In addition, applications in hydrogen environments might require specific material properties in terms of thermal and electrical conductivity, magnetic properties as well as corrosion resistance. In the present study, three high-strength Cu-base alloys (Alloy 25, PerforMet® and ToughMet® 3) as well as austenitic stainless AISI 321, Ni-base alloy IN 625 and ferritic steel 1.4511 are charged in pressurized hydrogen and subsequently tested by means of Slow Strain Rate Testing (SSRT). The results show that high-strength Cu-base alloys exhibit a great resistance to HE and could prove to be suitable for materials for a variety of hydrogen applications with rough conditions such as high pressure, elevated temperature and corrosive environments.
氢脆（HE）给许多金属，尤其是高强度钢带来过早失效的风险。由于氢是一种环境友好型能源，人们正在努力提高氢在高压和高温下的抗脆性。此外，氢环境中的应用可能要求材料在导热性、导电性、磁性和耐腐蚀性方面具有特定的性能。在本研究中，三种高强度铜基合金（Alloy 25、PerforMet® 和 ToughMet® 3）以及奥氏体不锈钢 AISI 321、镍基合金 IN 625 和铁素体钢 1.4511 都充入了加压氢气，随后通过慢应变速率测试 (SSRT) 进行了测试。结果表明，高强度铜基合金对 HE 具有很强的抵抗力，可证明是适用于高压、高温和腐蚀性环境等恶劣条件下各种氢气应用的材料。
{"title":"Effect of Hydrogen Charging on the Mechanical Properties of High-Strength Copper-Base Alloys, Austenitic Stainless Steel AISI 321, Inconel 625 and Ferritic Steel 1.4511","authors":"J. Jürgensen, Andreas Frehn, Klaus Ohla, Sandra Stolz, Michael Pohl","doi":"10.3390/met14050588","DOIUrl":"https://doi.org/10.3390/met14050588","url":null,"abstract":"Hydrogen embrittlement (HE) poses the risk of premature failure for many metals, especially high-strength steels. Due to the utilization of hydrogen as an environmentally friendly energy source, efforts are made to improve the resistance to HE at elevated pressures and temperatures. In addition, applications in hydrogen environments might require specific material properties in terms of thermal and electrical conductivity, magnetic properties as well as corrosion resistance. In the present study, three high-strength Cu-base alloys (Alloy 25, PerforMet® and ToughMet® 3) as well as austenitic stainless AISI 321, Ni-base alloy IN 625 and ferritic steel 1.4511 are charged in pressurized hydrogen and subsequently tested by means of Slow Strain Rate Testing (SSRT). The results show that high-strength Cu-base alloys exhibit a great resistance to HE and could prove to be suitable for materials for a variety of hydrogen applications with rough conditions such as high pressure, elevated temperature and corrosive environments.","PeriodicalId":510812,"journal":{"name":"Metals","volume":"90 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140964285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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