IF 3.8 2区材料科学

Vacuum Pub Date : 2025-03-07 DOI: 10.1016/j.vacuum.2025.114236

Jing-zhong Xu, Ze-yuan Gao, Ting-an Zhang, Yishan Liu, Yingqi Li, Hong-xuan Liu

引用次数: 0

Stable and high current emission of electrons from a HfC nanoneedle field-emitter fabricated by focused ion beam

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-03-06 DOI: 10.1016/j.vacuum.2025.114224

Shuai Tang , Jie Tang , Yimeng Wu , You-Hu Chen , Jun Uzuhashi , Tadakatsu Ohkubo , Masaki Takeguchi , Lu-Chang Qin

{"title":"Stable and high current emission of electrons from a HfC nanoneedle field-emitter fabricated by focused ion beam","authors":"Shuai Tang , Jie Tang , Yimeng Wu , You-Hu Chen , Jun Uzuhashi , Tadakatsu Ohkubo , Masaki Takeguchi , Lu-Chang Qin","doi":"10.1016/j.vacuum.2025.114224","DOIUrl":"10.1016/j.vacuum.2025.114224","url":null,"abstract":"<div><div>HfC nanoneedles with both excellent electron emission characteristics and robust structure are promising field-emission point electron sources, especially for applications desiring a high emission current. Herewith we report successful fabrication of HfC nanoneedle emitter by focused ion beam and its characterization. Transmission electron microscopy and energy dispersive X-ray spectroscopy examinations show that the HfC nanoneedle has a sharp tip with a radius of curvature of about 10 nm. Its atomic structure remains crystalline and it is aligned in a <100> direction. The HfC nanoneedle emitter has a low work function of 3.2 eV. It delivers an electron beam with a low turn-on field of 2.7 V/nm (at emission current of 2 nA) and a threshold field of 3.5 V/nm (at emission current of 50 nA), respectively. The HfC nanoneedle emitter also exhibits an excellent emission stability with a fluctuation of 1.5 % in 15 min under a high current (280 nA). The excellent current stability is attributed to the sharp tip lowering the extraction voltage that reduced ion bombardment and oxidation of the emitter surface with lowered activities in gas adsorption or desorption.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"238 ","pages":"Article 114224"},"PeriodicalIF":3.8,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143686973","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}

引用次数: 0

Silicon-based gallium oxide optical waveguide fabricated by MOCVD

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-03-06 DOI: 10.1016/j.vacuum.2025.114221

Yu Han , Wei Chen , Teng Jiao , Han Yu , Zhao Zhang , Xin Dong , Yuantao Zhang , Baolin Zhang

引用次数: 0

Tensile properties and molecular dynamics simulation of FeCrMnAlxCu high-entropy alloys

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-03-06 DOI: 10.1016/j.vacuum.2025.114219

Li Feng , Ruilong Liu , Kai Ma , Yanchun Zhao , Xuan Fu , Xian Zhang , Yajun Ling , Jun Li

{"title":"Tensile properties and molecular dynamics simulation of FeCrMnAlxCu high-entropy alloys","authors":"Li Feng , Ruilong Liu , Kai Ma , Yanchun Zhao , Xuan Fu , Xian Zhang , Yajun Ling , Jun Li","doi":"10.1016/j.vacuum.2025.114219","DOIUrl":"10.1016/j.vacuum.2025.114219","url":null,"abstract":"<div><div>High-entropy alloys with the composition FeCrMnAl<sub>x</sub>Cu (where x = 0, 0.1, 0.25, 0.5, 0.75, and 1.0) were synthesized utilizing vacuum arc melting techniques followed by Cu mold casting. This study systematically investigated the effects of different Al contents on the microstructure and mechanical properties of these alloys. The microstructural development and characteristics of FeCrMnAl<sub>x</sub>Cu high-entropy alloys under uniaxial tensile conditions were examined through molecular dynamics simulations. The experimental results indicated that as the Al content increased from 0 to 1.0, the alloy phase structure of the alloy before and after stretching was composed of FCC and BCC phases. Notably, the proportion of the BCC phase increased after stretching, while the dendrite region expanded and the interdendrite region decreased. The tensile strength decreased by 70.44 %, and elongation decreased by 87.14 % as the Al content increased from 0 to 1.0.t Additionally, molecular dynamics simulations revealed that the phase structure changed from the original FCC to a predominantly BCC configuration with increasing Al content. This increase adversely affected the mechanical properties of the FeCrMnAl<sub>x</sub>Cu high-entropy alloy, thereby leading to a reduction in dislocation density.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"238 ","pages":"Article 114219"},"PeriodicalIF":3.8,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580744","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}

引用次数: 0

Effect of deposition pressure on the microstructure, mechanical, and corrosion properties of tantalum nitride thin films deposited by reactive pulsed laser deposition

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-03-06 DOI: 10.1016/j.vacuum.2025.114228

Avery Bend , Venkata A.S. Kandadai , Jacob B. Petersen , Bharat K. Jasthi

{"title":"Effect of deposition pressure on the microstructure, mechanical, and corrosion properties of tantalum nitride thin films deposited by reactive pulsed laser deposition","authors":"Avery Bend , Venkata A.S. Kandadai , Jacob B. Petersen , Bharat K. Jasthi","doi":"10.1016/j.vacuum.2025.114228","DOIUrl":"10.1016/j.vacuum.2025.114228","url":null,"abstract":"<div><div>Tantalum nitride films have several beneficial properties that make them attractive for various applications, where protective coatings with excellent film integrity and corrosion resistance are essential. This study investigates the influence of deposition pressure (2, 5, and 8 mTorr) on the characteristics of tantalum nitride films synthesized by pulsed laser deposition in a pure nitrogen atmosphere. Microstructural analysis confirmed that extremely smooth films were produced, with increasing crystallinity correlated with higher deposition pressures. Grazing incidence X-ray diffraction and selective area electron diffraction analysis confirmed the formation of distinct phases, specifically hexagonal γ-Ta<sub>2</sub>N and cubic δ-TaN, in the deposited nanofilms. Decrease in hexagonal γ-Ta<sub>2</sub>N phase content from 90 wt% at 2 mTorr to 60 wt% at 8 mTorr was observed with corresponding increase in cubic δ-TaN phase content. The hardness and modulus of films were increased with increasing deposition pressure. Electrochemical studies conducted in 3.5 wt% NaCl solution indicated that the tantalum nitride film-coated titanium deposited at 2 mTorr exhibited a ∼6.4 times reduction in corrosion rates compared to uncoated titanium. Overall, the results suggest that deposition pressure significantly influenced the characteristics of the deposited films, indicating that the synthesis conditions can be effectively optimized for specific coating applications based on desired properties.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"238 ","pages":"Article 114228"},"PeriodicalIF":3.8,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143593540","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}

引用次数: 0

Fluid flow characteristics in RH vacuum refining with argon injection through down-leg snorkel

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-03-06 DOI: 10.1016/j.vacuum.2025.114227

Yang He , Shuo Zhang , Jianhua Liu , Xiaodong Yang , Jun Wang

{"title":"Fluid flow characteristics in RH vacuum refining with argon injection through down-leg snorkel","authors":"Yang He , Shuo Zhang , Jianhua Liu , Xiaodong Yang , Jun Wang","doi":"10.1016/j.vacuum.2025.114227","DOIUrl":"10.1016/j.vacuum.2025.114227","url":null,"abstract":"<div><div>The flow fluid characteristics in RH vacuum refining with argon injection through down-leg snorkel (AITDS) were investigated by conducting a physical modeling, treating an industrial RH facility as the prototype. The velocity distribution of flow field, mixing time, and circulation flow rate in the physical model were characterized using the particle image velocimetry (PIV), conductivity measurement, and ink tracing, respectively. The PIV results showed that the application of AITDS in RH refining led to the lifting of vortices between the down-leg snorkel and ladle wall, which was conducive to the stirring of liquid in this region. The liquid flow velocity inside the down-leg snorkel tended to reduce with the increasing flow rate of AITDS, resulting in the increase of mixing time at the ladle bottom region. It was suggested that the flow rate of AITDS should be set to 0.5 %–2 % of the lifting gas flow rate to balance both the efficiencies of bubble adhesion for inclusion removal and the circulation refining. Furthermore, the decarburization and degassing of RH refining with AITDS was discussed, and the reduction in circulation flow rate by AITDS had no noticeable negative impact on the control of final carbon, hydrogen, and nitrogen contents.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"238 ","pages":"Article 114227"},"PeriodicalIF":3.8,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601253","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}

引用次数: 0

Silver-graphene nanosheets flux and ultrasound-assisted synergistic enhancement of Sn-3Ag-0.5Cu solder joints: Study on interfacial reactions, mechanical properties

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-03-06 DOI: 10.1016/j.vacuum.2025.114223

Zhixiang Wu , Minming Zou , Wenjing Chen , Tao Xu , Xiongxin Jiang , Jue Wang , Sifan Tan , Jinghui Fan , Yanqing Lai , Yue Liu , Xiaowu Hu

{"title":"Silver-graphene nanosheets flux and ultrasound-assisted synergistic enhancement of Sn-3Ag-0.5Cu solder joints: Study on interfacial reactions, mechanical properties","authors":"Zhixiang Wu , Minming Zou , Wenjing Chen , Tao Xu , Xiongxin Jiang , Jue Wang , Sifan Tan , Jinghui Fan , Yanqing Lai , Yue Liu , Xiaowu Hu","doi":"10.1016/j.vacuum.2025.114223","DOIUrl":"10.1016/j.vacuum.2025.114223","url":null,"abstract":"<div><div>This research successfully prepared a composite flux containing varying concentrations of silver nanoparticle-modified graphene nanosheets (Ag-GNSs) through chemical modification. Additionally, ultrasonic vibration (USV) was brought into reflow process for improvement of mechanical properties. The individual and combined effects of Ag-GNSs composite flux and USV on the shear performance and microstructure of Sn-3.5Ag-0.5Cu/Cu (SAC305/Cu) solder joints have been thoroughly investigated. The application of composite flux effectively restrained the growth of intermetallic compound (IMC), suppressed the coarsening of grain, improved the shear strength of soldered samples. Furthermore, the IMC layer continuously thickened with extended aging time, the sample with 0.1 wt% Ag-GNS addition maintained the thinnest IMC among all joint. After introduced of USV, the shear performance of the soldered joints is increased varies to different extents due to the refinement of grain size and thinning of IMC layer. With increasing concentrations of composite flux, the reflowed joints transformed from brittle-ductile mixed fracture to ductile fracture mode, while all the USV-treated joints remain ductile fracture mode.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"238 ","pages":"Article 114223"},"PeriodicalIF":3.8,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580681","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}

引用次数: 0

TiSiN/AlCrN multilayer coatings with gradient modulation period deposited by HiPIMS: Mechanical and tribological properties

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-03-05 DOI: 10.1016/j.vacuum.2025.114217

Rong Tu , Yuanping Qiao , Mai Yang , Mingquan Jiang , Yibing Su , Yuzhe Han , Qizhong Li , Meijun Yang , Song Zhang , Takashi Goto

{"title":"TiSiN/AlCrN multilayer coatings with gradient modulation period deposited by HiPIMS: Mechanical and tribological properties","authors":"Rong Tu , Yuanping Qiao , Mai Yang , Mingquan Jiang , Yibing Su , Yuzhe Han , Qizhong Li , Meijun Yang , Song Zhang , Takashi Goto","doi":"10.1016/j.vacuum.2025.114217","DOIUrl":"10.1016/j.vacuum.2025.114217","url":null,"abstract":"<div><div>Hard nitride coatings with multilayer or gradient structures have been widely used in the field of machining, and their modulation period (Λ) plays a crucial role in it. In this study, high energy impulse magnetron sputtering (HiPIMS) was used to prepare four kinds of TiSiN/AlCrN multilayer coatings with different modulation periods and gradient variations in thickness (3.6–12.3 nm). The influence of Λ variation on the microstructure, mechanical properties, and wear resistance of coatings was studied. The coatings were mainly composed of fcc nanocrystals and a small amount of amorphous SiN<sub>x</sub>. The smaller Λ and gradient design result in unclear interlayer interfaces and mutual diffusion, displaying a coherent interface at Λ = 4.6 nm. The gradient variation of modulation period significantly improves the mechanical properties of the coating. The coating with an increasing and then decreasing modulation period (G3 gradient structure) exhibits the best mechanical properties, with the highest hardness (38.4 GPa), bonding strength (68.2 N), <em>H</em>/<em>E∗</em> (0.084), and <em>H</em><sup><em>3</em></sup>/<em>E∗</em><sup><em>2</em></sup> (0.380 GPa). Due to its high hardness and the presence of lubricating phases, G3 has the lowest wear rate (5 × 10<sup>−15</sup> m<sup>3</sup>N<sup>−1</sup>m<sup>−1</sup>) and a lower friction coefficient (0.34).</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"238 ","pages":"Article 114217"},"PeriodicalIF":3.8,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580680","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}

引用次数: 0

Role of pre-ageing treatment on microstructure evolution and strengthening mechanism of as-extruded Mg-Gd-Y-Mn-Sc alloy

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-03-05 DOI: 10.1016/j.vacuum.2025.114225

Zhao Yang , Chao Xu , Gang Wang , Kun Qian , Kaixuan Gui , Taiki Nakata , Shigeharu Kamado

{"title":"Role of pre-ageing treatment on microstructure evolution and strengthening mechanism of as-extruded Mg-Gd-Y-Mn-Sc alloy","authors":"Zhao Yang , Chao Xu , Gang Wang , Kun Qian , Kaixuan Gui , Taiki Nakata , Shigeharu Kamado","doi":"10.1016/j.vacuum.2025.114225","DOIUrl":"10.1016/j.vacuum.2025.114225","url":null,"abstract":"<div><div>The extruded Mg-8Gd-4Y-1Mn-0.4Sc (wt. %) alloy was fabricated by pre-ageing treatment and hot extrusion. Microstructure evolution and mechanical properties of the alloys with or without pre-ageing treatment were studied. The results show the dense nano-sized β′ phases and sub-micron particles precipitates inside grains after pre-ageing treatment, and the β’ phases coarsens and transforms into sub-micron β particles during pre-heating treatment. These particles obstructs the dynamic recrystallization process and restricts the grain growth during hot extrusion. Therefore, the bimodal microstructure composed of elongated un-dynamically recrystrallized (un-DRXed) grains and fine DRXed grains is formed in as-extruded Mg-8Gd-4Y-1Mn-0.4Sc (wt. %) alloys with or without pre-ageing treatment. The pre-aged-extruded (PE) sample exhibits a lower fraction of DRXed grains and densely distributed fine precipitates. The homogenized-extruded (HE) sample shows the optimal combination of strength and ductility, with tenslile yield strength (TYS) of 360 MPa, ultimate tensile strength (UTS) of 410 MPa, and elongation (EL) of 11.4 %, which is attributed to the bimodal microstructure, strong basal texture, and quantity of precipitated particles. The high fraction of un-DRXed regions and excessive sub-micron particles degrades the strength and ductility of PE sample.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"238 ","pages":"Article 114225"},"PeriodicalIF":3.8,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580682","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}

引用次数: 0

Microstructure evolution and tensile deformation behavior of an ultrahigh-strength Al-Mg-Mn-Sc-Zr alloy fabricated by laser powder bed fusion

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-03-05 DOI: 10.1016/j.vacuum.2025.114216

Jun Wang , Fencheng Liu , Xiaobin Yu , Fenggang Liu , Wugui Jiang , Zihong Wang , Chunping Huang , Xin Lin

{"title":"Microstructure evolution and tensile deformation behavior of an ultrahigh-strength Al-Mg-Mn-Sc-Zr alloy fabricated by laser powder bed fusion","authors":"Jun Wang , Fencheng Liu , Xiaobin Yu , Fenggang Liu , Wugui Jiang , Zihong Wang , Chunping Huang , Xin Lin","doi":"10.1016/j.vacuum.2025.114216","DOIUrl":"10.1016/j.vacuum.2025.114216","url":null,"abstract":"<div><div>In recent years, it has been proved to be an effective strategy to obtain high strength and ultrahigh-strength Al alloys by laser powder bed fusion (LPBF). However, these ultrahigh-strength LPBFed Al alloys are difficult to achieve good ductility. In this work, high content of Sc/Zr modified Al-Mg-Mn-Sc-Zr alloy was prepared by LPBF. The high content of Sc/Zr brought unique heterogeneous microstructure and further affected the tensile deformation behavior of the alloy. It was found that the precipitation of primary Al<sub>3</sub>(Sc,Zr) phase significantly increased the number of nucleation sites at the front of the liquid-solid interface and promoted the columnar-to-equiaxed transition (CET), leading to a microstructure of near-full equiaxed grains with a grain size range from 0.55 μm to 1.10 μm. Tensile tests showed that the yield strength of the as-built sample was 442 MPa, and the strengthening effect brought by ultrafine grains plays a leading role, which is difficult to achieve for the Al-Mg-Mn-Sc-Zr alloy with low Sc/Zr content. After aging treatment, the yield strength of the LPBFed Al-Mg-Mn-Sc-Zr alloy reached up to 613 ± 5 MPa under the combined effects of grain-boundary strengthening and precipitation strengthening. The decrease of work-hardening capacity induced a longer Lüders elongation after aging, but the reliable dislocation accumulation ability of coarse grains still existed, which finally made the elongation of the as-aged sample reach 11.7 ± 0.5 %.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"238 ","pages":"Article 114216"},"PeriodicalIF":3.8,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610158","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}

引用次数: 0

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