Pub Date : 2025-01-22DOI: 10.1016/j.vacuum.2025.114057
Ziwei Guo, Yamei Mao
Gallium oxide (Ga₂O₃) thin films were successfully deposited on 6° off-axis sapphire substrates using RF magnetron sputtering, and the effects of varying growth pressures on structural, optical, and stress properties were systematically explored. AFM, SEM, and XRD analyses showed significant changes in surface roughness, film thickness, and crystal orientation as pressure increased from 5 to 15 mTorr. At 10 mTorr, the films exhibited the highest crystallinity, smoothest surface, and most uniform orientation. TEM and GPA revealed internal stress was minimized at this pressure, reducing stress-induced distortions. XPS analysis confirmed that the oxidation process is more efficient at specific pressures (e.g., 10 mTorr) compared to lower or higher pressures tested in the study. Optical measurements showed films deposited at 10 mTorr achieved the highest transmittance and largest bandgap, identifying 10 mTorr as the optimal condition for high-quality Ga₂O₃ films.
{"title":"Optimization of Ga2O3 thin film growth via magnetron sputtering: Influence of growth pressure on crystallinity, surface morphology, and optical properties","authors":"Ziwei Guo, Yamei Mao","doi":"10.1016/j.vacuum.2025.114057","DOIUrl":"10.1016/j.vacuum.2025.114057","url":null,"abstract":"<div><div>Gallium oxide (Ga₂O₃) thin films were successfully deposited on 6° off-axis sapphire substrates using RF magnetron sputtering, and the effects of varying growth pressures on structural, optical, and stress properties were systematically explored. AFM, SEM, and XRD analyses showed significant changes in surface roughness, film thickness, and crystal orientation as pressure increased from 5 to 15 mTorr. At 10 mTorr, the films exhibited the highest crystallinity, smoothest surface, and most uniform orientation. TEM and GPA revealed internal stress was minimized at this pressure, reducing stress-induced distortions. XPS analysis confirmed that the oxidation process is more efficient at specific pressures (e.g., 10 mTorr) compared to lower or higher pressures tested in the study. Optical measurements showed films deposited at 10 mTorr achieved the highest transmittance and largest bandgap, identifying 10 mTorr as the optimal condition for high-quality Ga₂O₃ films.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"234 ","pages":"Article 114057"},"PeriodicalIF":3.8,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143205539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-21DOI: 10.1016/j.vacuum.2025.114059
Enshen Zhang , Hailing Sun , Jinjin Zheng , Xiu Wang , Mai Xu , Shiliu Yang , Lvlv Gao
Binary metal selenides are promised as potential anodes for sodium storage by the reason of their desirable theoretical specific capacity and satisfied electronic conductivity. Nevertheless, the binary-metal selenides anodes normally undergo serious volume change and unsatisfactory cycle life. Herein, the porous core-shell structured nitrogen doped carbon coated Cu2SnSe4 nanorod (Cu2SnSe4@NC) was obtained by simple template method. The porous core-shell structure not only relieves volume effect of Cu2SnSe4@NC anode, but also promotes the electrolyte infiltration and facilitates Na+ migration. Moreover, the bimetallic composition and nitrogen doped carbon shell speed up electron transform and exhibit high-rate of Cu2SnSe4@NC anode. Benefiting from the above advantages, Cu2SnSe4@NC anode shows favorable electrochemical performance. The Cu2SnSe4@NC delivered a capacity of 263 mAh g−1 at 7.0 A g−1, and showed an excellent cyclic stability of 311 mAh g−1 over 800 cycles at 2.0 A g−1.
{"title":"Porous core-shell structured nitrogen doped carbon coated Cu2SnSe4 nanorod for improved sodium ion battery anode","authors":"Enshen Zhang , Hailing Sun , Jinjin Zheng , Xiu Wang , Mai Xu , Shiliu Yang , Lvlv Gao","doi":"10.1016/j.vacuum.2025.114059","DOIUrl":"10.1016/j.vacuum.2025.114059","url":null,"abstract":"<div><div>Binary metal selenides are promised as potential anodes for sodium storage by the reason of their desirable theoretical specific capacity and satisfied electronic conductivity. Nevertheless, the binary-metal selenides anodes normally undergo serious volume change and unsatisfactory cycle life. Herein, the porous core-shell structured nitrogen doped carbon coated Cu<sub>2</sub>SnSe<sub>4</sub> nanorod (Cu<sub>2</sub>SnSe<sub>4</sub>@NC) was obtained by simple template method. The porous core-shell structure not only relieves volume effect of Cu<sub>2</sub>SnSe<sub>4</sub>@NC anode, but also promotes the electrolyte infiltration and facilitates Na<sup>+</sup> migration. Moreover, the bimetallic composition and nitrogen doped carbon shell speed up electron transform and exhibit high-rate of Cu<sub>2</sub>SnSe<sub>4</sub>@NC anode. Benefiting from the above advantages, Cu<sub>2</sub>SnSe<sub>4</sub>@NC anode shows favorable electrochemical performance. The Cu<sub>2</sub>SnSe<sub>4</sub>@NC delivered a capacity of 263 mAh g<sup>−1</sup> at 7.0 A g<sup>−1</sup>, and showed an excellent cyclic stability of 311 mAh g<sup>−1</sup> over 800 cycles at 2.0 A g<sup>−1</sup>.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"234 ","pages":"Article 114059"},"PeriodicalIF":3.8,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143266032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-21DOI: 10.1016/j.vacuum.2025.114058
Yu Wang , Helei Dong , Zhen Jia , Yuxin Miao , Jie Ma , Zhonghai Luo , Lei Zhang , Yongqiang Qin , Qiulin Tan
In this paper, an indium tin oxide (ITO) and indium oxide (In2O3) slurry that can be used for low-temperature sintering was prepared, after which an ITO/In2O3 thermocouple was prepared on an aluminum oxide (Al2O3) ceramic substrate using a screen-printing process for verifying its comprehensive performance. The samples were treated at an annealing temperature of 900 °C for different times. The characterization results show that when the annealing time is set to 3 h, the ITO film has the best crystallization effect. Moreover, under this annealing condition, Sn2⁺ ions are more inclined to transform into Sn⁴⁺ ions, promoting the release of additional free electrons, which significantly enhances the thermoelectric effect. The test result of its electrical conductivity is 134.2 s/cm. Within the temperature range of 900 °C, the thermocouple has an ultra-high Seebeck coefficient of 410.91 μV/°C, and the peak output voltage is 332.8 mV. The maximum repeatability error is 2.745 %. It can be seen that the slurry prepared in this paper has excellent electrical properties after sintering at 900 °C, and is expected to become a feasible substitute in the field of conductive slurry of low temperature co-fired ceramic (LTCC).
{"title":"Research on the optimization of electrical properties for low-temperature sintered indium tin oxide slurry","authors":"Yu Wang , Helei Dong , Zhen Jia , Yuxin Miao , Jie Ma , Zhonghai Luo , Lei Zhang , Yongqiang Qin , Qiulin Tan","doi":"10.1016/j.vacuum.2025.114058","DOIUrl":"10.1016/j.vacuum.2025.114058","url":null,"abstract":"<div><div>In this paper, an indium tin oxide (ITO) and indium oxide (In<sub>2</sub>O<sub>3</sub>) slurry that can be used for low-temperature sintering was prepared, after which an ITO/In<sub>2</sub>O<sub>3</sub> thermocouple was prepared on an aluminum oxide (Al<sub>2</sub>O<sub>3</sub>) ceramic substrate using a screen-printing process for verifying its comprehensive performance. The samples were treated at an annealing temperature of 900 °C for different times. The characterization results show that when the annealing time is set to 3 h, the ITO film has the best crystallization effect. Moreover, under this annealing condition, Sn<sup>2</sup>⁺ ions are more inclined to transform into Sn⁴⁺ ions, promoting the release of additional free electrons, which significantly enhances the thermoelectric effect. The test result of its electrical conductivity is 134.2 s/cm. Within the temperature range of 900 °C, the thermocouple has an ultra-high Seebeck coefficient of 410.91 μV/°C, and the peak output voltage is 332.8 mV. The maximum repeatability error is 2.745 %. It can be seen that the slurry prepared in this paper has excellent electrical properties after sintering at 900 °C, and is expected to become a feasible substitute in the field of conductive slurry of low temperature co-fired ceramic (LTCC).</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"234 ","pages":"Article 114058"},"PeriodicalIF":3.8,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143206010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-21DOI: 10.1016/j.vacuum.2025.114049
Yu Liu , Fei Li , ZuSheng Zhou , OuZheng Xiao , YiAo Wang , WenBin Gao , Han Xiao , FanYu Wang , ZhanDong Zhang , YunLong Chi , Abid Aleem , Munawar Iqbal , Noman Habib , XinAn Xu
Klystrons are the predominant RF power sources utilized in large particle accelerators, and enhancing klystron efficiency is crucial for reducing the overall energy consumption of these accelerators. One optional approach to improve klystron efficiency is implementing the depressed collector technique, successfully applied in low-power microwave electronic vacuum devices such as TWT and TV communication klystrons. While the theoretical advancements in klystron efficiency are promising, the practical integration of these techniques, particularly in high-power klystrons, remains challenging. In this paper, a depressed collector design applied to high-power klystrons will be proposed, laying the foundation for improving the overall efficiency of the RF power source in the Circular Electron Positron Collider(CEPC). To verify the key technology of energy recovery for the klystron, we designed an energy recovery verification device composed of an electron gun and a collector. The one-stage depressed collector was theoretically analyzed, and the electrode parameters were determined through simulation design. Beam optics was simulated using DGUN and CST software, while thermal analysis of the collector was performed with ANSYS software. The structural design of the collector was optimized to meet electrical insulation and breakdown requirements. Additionally, secondary electron emission was considered, and its effect on reflux electrons was mitigated, achieving a collector efficiency simulation result of 88.2 %.
{"title":"Development of energy recovery scheme for high-power depressed collector","authors":"Yu Liu , Fei Li , ZuSheng Zhou , OuZheng Xiao , YiAo Wang , WenBin Gao , Han Xiao , FanYu Wang , ZhanDong Zhang , YunLong Chi , Abid Aleem , Munawar Iqbal , Noman Habib , XinAn Xu","doi":"10.1016/j.vacuum.2025.114049","DOIUrl":"10.1016/j.vacuum.2025.114049","url":null,"abstract":"<div><div>Klystrons are the predominant RF power sources utilized in large particle accelerators, and enhancing klystron efficiency is crucial for reducing the overall energy consumption of these accelerators. One optional approach to improve klystron efficiency is implementing the depressed collector technique, successfully applied in low-power microwave electronic vacuum devices such as TWT and TV communication klystrons. While the theoretical advancements in klystron efficiency are promising, the practical integration of these techniques, particularly in high-power klystrons, remains challenging. In this paper, a depressed collector design applied to high-power klystrons will be proposed, laying the foundation for improving the overall efficiency of the RF power source in the Circular Electron Positron Collider(CEPC). To verify the key technology of energy recovery for the klystron, we designed an energy recovery verification device composed of an electron gun and a collector. The one-stage depressed collector was theoretically analyzed, and the electrode parameters were determined through simulation design. Beam optics was simulated using DGUN and CST software, while thermal analysis of the collector was performed with ANSYS software. The structural design of the collector was optimized to meet electrical insulation and breakdown requirements. Additionally, secondary electron emission was considered, and its effect on reflux electrons was mitigated, achieving a collector efficiency simulation result of 88.2 %.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"234 ","pages":"Article 114049"},"PeriodicalIF":3.8,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143206044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A promising approach to improve the high-temperature properties of Ni-Al intermetallics is macroalloying with chromium and microalloying with a small amount of rare-earth elements (REE). For powder manufacturing processes such as the combustion synthesis technique, macro- and microalloying can be achieved by employing Cr & REE containing masteralloy powders as one of the starting reagents along with nickel and aluminum powders. This study investigated a process of dysprosium deposition onto the particles of commercial Ni-Cr powder aimed to produce the Ni-Cr-Dy masteralloy powder. The process involves pretreatment of the particle surface by low-energy high-current electron beam (LEHCEB) and uniform magnetron deposition of a thin dysprosium film. The possibility of embedding the dysprosium film into the particle's surface using an additional stage of LEHCEB treatment has been considered. It has been observed that during LEHCEB modification, a change in the particle size distribution, smoothing of the surface, and the formation of an intermetallic Dy3Ni phase in the subsurface layer occurs. A fraction of the obtained Ni-Cr-Dy powders were added to the starting powder blend for the combustion synthesis of Ni-Al-Cr-Dy porous alloys. It has been demonstrated that dysprosium uniformly distributes throughout the intermetallic scaffold of porous alloys and is localized within the Ni3Al phase in the form of enriched regions and separate inclusions.
{"title":"Application of vacuum plasma techniques for preparation of Ni-Cr-Dy powders proposed as masteralloys for combustion synthesis of Ni-Al intermetallics","authors":"Evgeniy Pesterev, Evgeniy Yakovlev, Nikita Pichugin, Vsevolod Petrov, Anatoly Maznoy","doi":"10.1016/j.vacuum.2025.114054","DOIUrl":"10.1016/j.vacuum.2025.114054","url":null,"abstract":"<div><div>A promising approach to improve the high-temperature properties of Ni-Al intermetallics is macroalloying with chromium and microalloying with a small amount of rare-earth elements (REE). For powder manufacturing processes such as the combustion synthesis technique, macro- and microalloying can be achieved by employing Cr & REE containing masteralloy powders as one of the starting reagents along with nickel and aluminum powders. This study investigated a process of dysprosium deposition onto the particles of commercial Ni-Cr powder aimed to produce the Ni-Cr-Dy masteralloy powder. The process involves pretreatment of the particle surface by low-energy high-current electron beam (LEHCEB) and uniform magnetron deposition of a thin dysprosium film. The possibility of embedding the dysprosium film into the particle's surface using an additional stage of LEHCEB treatment has been considered. It has been observed that during LEHCEB modification, a change in the particle size distribution, smoothing of the surface, and the formation of an intermetallic Dy<sub>3</sub>Ni phase in the subsurface layer occurs. A fraction of the obtained Ni-Cr-Dy powders were added to the starting powder blend for the combustion synthesis of Ni-Al-Cr-Dy porous alloys. It has been demonstrated that dysprosium uniformly distributes throughout the intermetallic scaffold of porous alloys and is localized within the Ni<sub>3</sub>Al phase in the form of enriched regions and separate inclusions.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"234 ","pages":"Article 114054"},"PeriodicalIF":3.8,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143265953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-21DOI: 10.1016/j.vacuum.2025.114061
T.del N.J. Sánchez-Cruz , V.H. López-Morelos , J.A. González–Sánchez , H. Granados-Becerra , F.F. Curiel-López
The electrochemical behaviour of the passive film formed over the surface of dissimilar welds of AISI 2205 duplex stainless steel and AISI 316L austenitic stainless steel was evaluated using electrochemical impedance spectroscopy (EIS). Gas metal arc welding (GMAW) of the plates, 6.35 mm thick, was performed using ER309L and ER316L-Si filler wires with pulsed (GMAW-P) and spray (GMAW-S) transfer modes. The passive film resistance was determined conducting EIS tests at different anodic overpotentials (0.05, 0.150, 0.250 and 0.375 V). The results showed that increasing the anodic overpotential up to 0.250 V, led to the formation of a thicker, continuous and stable passive layer.
{"title":"Electrochemical impedance spectroscopy study of the passive state of 316L/2205 dissimilar welded joints","authors":"T.del N.J. Sánchez-Cruz , V.H. López-Morelos , J.A. González–Sánchez , H. Granados-Becerra , F.F. Curiel-López","doi":"10.1016/j.vacuum.2025.114061","DOIUrl":"10.1016/j.vacuum.2025.114061","url":null,"abstract":"<div><div>The electrochemical behaviour of the passive film formed over the surface of dissimilar welds of AISI 2205 duplex stainless steel and AISI 316L austenitic stainless steel was evaluated using electrochemical impedance spectroscopy (EIS). Gas metal arc welding (GMAW) of the plates, 6.35 mm thick, was performed using ER309L and ER316L-Si filler wires with pulsed (GMAW-P) and spray (GMAW-S) transfer modes. The passive film resistance was determined conducting EIS tests at different anodic overpotentials (0.05, 0.150, 0.250 and 0.375 V). The results showed that increasing the anodic overpotential up to 0.250 V, led to the formation of a thicker, continuous and stable passive layer.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"234 ","pages":"Article 114061"},"PeriodicalIF":3.8,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143205889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-20DOI: 10.1016/j.vacuum.2025.114056
Lanfeng Li , Yunfeng Wu , Xianrong Li , Haiying Du , Yaowen Xu , Zihan Guo , Naisen Yu
Hydrolysis of InN film was employed for synthesis of a self-powered In(OH)3/InN heterostructure photodetector. This novel heterostructure exhibited high performance in detecting white light in self-powered mode. The method eliminates the need for additional processing steps and equipment, thereby streamlining the overall process and reducing costs. The result presents a promising approach for the development of innovative photodetectors by integrating In(OH)3 nanostructures on InN. This research provides a promising strategy for the development of innovative photodetectors using InN film, thereby expanding the scope of potential applications in photoconversion technologies.
{"title":"Self-powered white light detector based on surface hydrolyzed InN film via aqueous method","authors":"Lanfeng Li , Yunfeng Wu , Xianrong Li , Haiying Du , Yaowen Xu , Zihan Guo , Naisen Yu","doi":"10.1016/j.vacuum.2025.114056","DOIUrl":"10.1016/j.vacuum.2025.114056","url":null,"abstract":"<div><div>Hydrolysis of InN film was employed for synthesis of a self-powered In(OH)<sub>3</sub>/InN heterostructure photodetector. This novel heterostructure exhibited high performance in detecting white light in self-powered mode. The method eliminates the need for additional processing steps and equipment, thereby streamlining the overall process and reducing costs. The result presents a promising approach for the development of innovative photodetectors by integrating In(OH)<sub>3</sub> nanostructures on InN. This research provides a promising strategy for the development of innovative photodetectors using InN film, thereby expanding the scope of potential applications in photoconversion technologies.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"234 ","pages":"Article 114056"},"PeriodicalIF":3.8,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143206013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-20DOI: 10.1016/j.vacuum.2025.114052
Tian-Xing Yang , Shigeharu Ukai , Peng Dou
Fe–Cr ODS steels are considered as promising materials for the fusion reactor blankets and the cladding of sodium-cooled fast reactors. For 9Cr ferritic/martensitic (F/M) (Fe–9Cr–0.14C–2W–0.23Ti–0.37Y2O3) and 12Cr ferritic (Fe–12Cr–0.027C–2W–0.23Ti–0.24Y2O3) ODS steels, the morphology of matrix grains and nanoparticles, as well as crystal & interface structures of nano-oxides were studied by TEM, STEM and HRTEM. For 9Cr F/M ODS steel, the particle dispersion morphology of the residual ferrite is much better than that of tempered martensite. The proportions of coherent/semi-coherent particles in residual ferrite of 9Cr F/M ODS steel and matrix of12Cr ferritic ODS steel are ∼83.7 % and ∼87.5 %, respectively, and however, for tempered martensite of 9Cr F/M ODS steel, the proportion is only ∼7.9 %, which explains the facts that the oxide particle dispersion morphology of ferritic matrix (i.e., residual ferrite of 9Cr F/M ODS steel and the matrix of 12Cr ferritic ODS steel) is much better than that of tempered martensite of 9Cr F/M ODS steel. Moreover, the results of first-principles calculations indicate that Y2TiO5 and Y2Ti2O7 oxides have excellent kinetic and thermal stability, which contribute to the high-temperature stability of both ODS steels. The findings provide valuable insights for the optimization and development of advanced ODS steels.
{"title":"Effects of matrix microstructure on oxide nanoparticles in 9Cr F/M and 12Cr ferritic ODS steels","authors":"Tian-Xing Yang , Shigeharu Ukai , Peng Dou","doi":"10.1016/j.vacuum.2025.114052","DOIUrl":"10.1016/j.vacuum.2025.114052","url":null,"abstract":"<div><div>Fe–Cr ODS steels are considered as promising materials for the fusion reactor blankets and the cladding of sodium-cooled fast reactors. For 9Cr ferritic/martensitic (F/M) (Fe–9Cr–0.14C–2W–0.23Ti–0.37Y<sub>2</sub>O<sub>3</sub>) and 12Cr ferritic (Fe–12Cr–0.027C–2W–0.23Ti–0.24Y<sub>2</sub>O<sub>3</sub>) ODS steels, the morphology of matrix grains and nanoparticles, as well as crystal & interface structures of nano-oxides were studied by TEM, STEM and HRTEM. For 9Cr F/M ODS steel, the particle dispersion morphology of the residual ferrite is much better than that of tempered martensite. The proportions of coherent/semi-coherent particles in residual ferrite of 9Cr F/M ODS steel and matrix of12Cr ferritic ODS steel are ∼83.7 % and ∼87.5 %, respectively, and however, for tempered martensite of 9Cr F/M ODS steel, the proportion is only ∼7.9 %, which explains the facts that the oxide particle dispersion morphology of ferritic matrix (i.e., residual ferrite of 9Cr F/M ODS steel and the matrix of 12Cr ferritic ODS steel) is much better than that of tempered martensite of 9Cr F/M ODS steel. Moreover, the results of first-principles calculations indicate that Y<sub>2</sub>TiO<sub>5</sub> and Y<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub> oxides have excellent kinetic and thermal stability, which contribute to the high-temperature stability of both ODS steels. The findings provide valuable insights for the optimization and development of advanced ODS steels.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"234 ","pages":"Article 114052"},"PeriodicalIF":3.8,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143206046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-20DOI: 10.1016/j.vacuum.2025.114053
Jiachen Yu
Designing heterogeneous structures within high-entropy alloys (HEAs) is a promising strategy to overcome the wear resistance and mechanical performance. In this study, we explore the tribological behavior and wear mechanisms of in-situ precipitation-strengthened HEAs with a tailored heterogeneous design. The reduced wear rates and enhanced durability result from precipitation strengthening and unique microstructural features, such as precipitate distribution and grain boundaries. The wear mechanism combines adhesive and abrasive wear, mitigated by these microstructural heterogeneities. These findings highlight the importance of heterogeneous design in optimizing the wear resistance of HEAs, opening new avenues for the development of advanced, high-performance materials with exceptional tribological properties. This work emphasizes the potential of leveraging powder metallurgy to efficiently and precisely control and optimize the multi-scale microstructure of HEAs, enhancing their tribological performance for demanding applications.
{"title":"Tribological behavior and wear mechanism of in-situ precipitation strengthened high-entropy alloys with heterogeneous design","authors":"Jiachen Yu","doi":"10.1016/j.vacuum.2025.114053","DOIUrl":"10.1016/j.vacuum.2025.114053","url":null,"abstract":"<div><div>Designing heterogeneous structures within high-entropy alloys (HEAs) is a promising strategy to overcome the wear resistance and mechanical performance. In this study, we explore the tribological behavior and wear mechanisms of in-situ precipitation-strengthened HEAs with a tailored heterogeneous design. The reduced wear rates and enhanced durability result from precipitation strengthening and unique microstructural features, such as precipitate distribution and grain boundaries. The wear mechanism combines adhesive and abrasive wear, mitigated by these microstructural heterogeneities. These findings highlight the importance of heterogeneous design in optimizing the wear resistance of HEAs, opening new avenues for the development of advanced, high-performance materials with exceptional tribological properties. This work emphasizes the potential of leveraging powder metallurgy to efficiently and precisely control and optimize the multi-scale microstructure of HEAs, enhancing their tribological performance for demanding applications.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"234 ","pages":"Article 114053"},"PeriodicalIF":3.8,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143351620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-19DOI: 10.1016/j.vacuum.2025.114048
Md Obidul Islam , Rawdah Mahmood , Hani E. Elsayed-Ali
A niobium laser multicharged ion source was developed using laser ablation with 10-ns, 1064-nm pulses and a laser fluence of 10–83 Jcm−2. Three distinct groups of Nb ions were detected: ultrafast, fast, and thermal. The ions were accelerated and allowed to drift in a transport line containing an electrostatic ion energy analyzer, a retarding field analyzer, and a Faraday cup. Analysis of the ion energy and charge (z) showed that each group of ions experienced different acceleration potentials during plasma expansion. Time-of-flight (TOF) signal of the thermal ions showed overlap of the signals from Nb1+ and Nb2+. For the fast ion group, z up to Nb7+ was observed and the ion acceleration potential during plasma expansion increased with z, over the charge states from Nb1+ to Nb7+. The TOF signal indicated that the ultrafast ions were composed of higher-charge ions.
{"title":"Ion emission from niobium nanosecond laser plasma","authors":"Md Obidul Islam , Rawdah Mahmood , Hani E. Elsayed-Ali","doi":"10.1016/j.vacuum.2025.114048","DOIUrl":"10.1016/j.vacuum.2025.114048","url":null,"abstract":"<div><div>A niobium laser multicharged ion source was developed using laser ablation with 10-ns, 1064-nm pulses and a laser fluence of 10–83 Jcm<sup>−2</sup>. Three distinct groups of Nb ions were detected: ultrafast, fast, and thermal. The ions were accelerated and allowed to drift in a transport line containing an electrostatic ion energy analyzer, a retarding field analyzer, and a Faraday cup. Analysis of the ion energy and charge (z) showed that each group of ions experienced different acceleration potentials during plasma expansion. Time-of-flight (TOF) signal of the thermal ions showed overlap of the signals from Nb<sup>1+</sup> and Nb<sup>2+</sup>. For the fast ion group, z up to Nb<sup>7+</sup> was observed and the ion acceleration potential during plasma expansion increased with <em>z</em>, over the charge states from Nb<sup>1+</sup> to Nb<sup>7+</sup>. The TOF signal indicated that the ultrafast ions were composed of higher-charge ions.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"234 ","pages":"Article 114048"},"PeriodicalIF":3.8,"publicationDate":"2025-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143206043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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