Vacuum最新文献

{"title":"Martensite instability induced surface hardening on gradient nano-structured 316L stainless steel","authors":"Y.B. Lei ,&nbsp;Z.M. Niu ,&nbsp;B. Gao ,&nbsp;Y.T. Sun","doi":"10.1016/j.vacuum.2024.113831","DOIUrl":"10.1016/j.vacuum.2024.113831","url":null,"abstract":"<div><div>Gradient nanostructured (GNS) 316L stainless steel manufactured by surface mechanical rolling treatment (SMRT) with a full martensitic phase on the surface exhibits an extraordinary annealed hardening. The surface hardness increases by 44 % from 4.1 GPa of the SMRTed 316L stainless steel up to 5.9 GPa after annealed at 400 °C for 120 min. Surface hardening is primarily attributed to the formation of low angle grain boundaries (LAGBs) within the original nano-grains. LAGBs function as substructures that effectively divide the grains into smaller units. These LAGBs originate from lattice distortions caused by Ni segregation during the annealing process. Furthermore, the redistribution of Ni can be regarded as a nucleation step leading to phase reversion from martensite to austenite. Additionally, the presence of Ni-enriched zones distributed within the martensite matrix serves to hinder dislocation movement, thus contributing to the observed surface hardening.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113831"},"PeriodicalIF":3.8,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657455","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}

{"title":"Molecular dynamics study on the mechanical behavior and deformation mechanism of gradient oxygen content nano-polycrystalline α-T","authors":"Junqiang Ren ,&nbsp;Xinyue Zhang ,&nbsp;Qing Gao ,&nbsp;Qi Wang ,&nbsp;Junchen Li ,&nbsp;Hongtao Xue ,&nbsp;Xuefeng Lu ,&nbsp;Fuling Tang","doi":"10.1016/j.vacuum.2024.113830","DOIUrl":"10.1016/j.vacuum.2024.113830","url":null,"abstract":"<div><div>Interstitial oxygen significantly affects the mechanical properties of <em>α</em>-Titanium (<em>α</em>-Ti) by modifying dislocation slip and deformation twinning mechanisms. This study utilizes molecular dynamics simulations to investigate the influence of interstitial oxygen atoms on the tensile mechanical properties and deformation mechanisms of nano polycrystalline <em>α</em>-Ti, taking into account two distinct average grain sizes and varying gradients of oxygen content. The pinning effect of interstitial oxygen atoms on grain boundary relaxation dislocations is critical for stabilizing the nano-polycrystalline grain boundaries (GBs), with this effect becoming increasingly pronounced as the oxygen content rises. Additionally, the simulation results indicate that oxygen atoms at the twin boundary enhance the stability of the {10 <span><math><mrow><mover><mn>1</mn><mo>‾</mo></mover></mrow></math></span> 2} twin boundary while exerting minimal influence on the migration of the {10<span><math><mrow><mover><mn>1</mn><mo>‾</mo></mover></mrow></math></span> 1} twin boundary. The deformation associated with {10<span><math><mrow><mover><mn>1</mn><mo>‾</mo></mover></mrow></math></span> 1} twinning leads to a crystallographic orientation transformation of the entire grain, which contrasts with the conventional grain rotation mechanism typically observed in nanocrystals. During plastic deformation, the primary dislocation slip mechanism is identified as the Shockley partial dislocation <span><math><mrow><mfrac><mn>1</mn><mn>3</mn></mfrac></mrow></math></span> &lt;<span><math><mrow><mover><mn>1</mn><mo>‾</mo></mover></mrow></math></span> 100&gt;, whereas the basal plane perfect dislocation <span><math><mrow><mfrac><mn>1</mn><mn>3</mn></mfrac></mrow></math></span> &lt;11<span><math><mrow><mover><mn>2</mn><mo>‾</mo></mover></mrow></math></span> 0&gt; easily dissociates into two Shockley partial dislocations due to the pinning effect of oxygen atoms. As a result, the dislocation density of the Shockley partial dislocation <span><math><mrow><mfrac><mn>1</mn><mn>3</mn></mfrac></mrow></math></span> &lt;<span><math><mrow><mover><mn>1</mn><mo>‾</mo></mover></mrow></math></span> 100&gt; is the highest.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113830"},"PeriodicalIF":3.8,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657369","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}

{"title":"Design a self-reinforcement buffer layer to assist braze SiC and Nb with Cu-xTiH2 filler alloy","authors":"Qiang Ma ,&nbsp;Zhekai Zhu ,&nbsp;Peng He ,&nbsp;Yongwei Chen ,&nbsp;Shujin Chen ,&nbsp;Jun Wang","doi":"10.1016/j.vacuum.2024.113829","DOIUrl":"10.1016/j.vacuum.2024.113829","url":null,"abstract":"<div><div>A buffer layer was designed to assist to braze SiC and Nb. The effect of brazing temperature and holding time on the microstructure and the shear strength of the joint was analyzed. The strengthening mechanism of the joint was evaluated. The results found that the SiC-Nb joint was brazed with Cu-5TiH₂, because of its good wettability on the surface of SiC. The typical microstructure of SiC-Nb joint brazed at 1060 °C for 5 min was SiC/C particles + TiC + Cu(s,s)/α-Ti + Nb(s,s)/Cu(s,s)+(Ti,Nb)₅Si₃+Ti₅Si₃/α-Ti/(Ti,Nb)Si/Nb. In addition, a buffer layer formed, which was consisted of two parts: reaction layer (α-Ti + Nb(s,s)) and infiltration layer (much C particles, little TiC and Cu(s,s)). With brazing temperature and holding time increasing, element Nb continuously diffused into brazing seam and solidified into α-Ti. With Nb content increasing, the α-Ti existed in the form of discontinuous to continuous layer, and then to particles. When Nb solidified into α-Ti continuous layer, the strength of the layer was improved and effective joining between SiC and Nb formed. In addition, the buffer layer was contributed to forming a good gradient transition of coefficient of thermal expansion (CTE), and released residual stress. So, the shear strength of the joint was increased to 52.6 MPa.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113829"},"PeriodicalIF":3.8,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659328","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}

{"title":"Preparation of Au@AuAg yolk-shell nanoparticles with porous surface and their catalytic reduction of 4-nitrophenol","authors":"Meng Yao,&nbsp;Sitong Zhao,&nbsp;Xiankui Lv,&nbsp;Junqi Tang","doi":"10.1016/j.vacuum.2024.113828","DOIUrl":"10.1016/j.vacuum.2024.113828","url":null,"abstract":"<div><div>Yolk-shell structure nanoparticles, consisting of outer shell, inner core and cavity, are a combination of core-shell structure and hollow structure. Due to the existence of their internal gaps, yolk-shell nanostructures have more excellent optoelectronic properties than hollow nanostructures and core-shell nanostructures, and have promising applications in catalysis, energy storage, drug delivery, lithium batteries, biosensors and nanoreactors. In this paper, gold-silver bimetallic yolk-shell nanoparticles (Au@AuAg Y-SNPs) with porous surface structure were synthesized. The morphology and structure of Au@AuAg Y-SNPs were characterized by UV–vis, XRD, SEM, TEM, HRTEM, SAED, and HAADF-STEM, the results demonstrated that the nanostructures are composed of gold and silver bimetals with various shell thickness, and tunable internal voids. In addition, the catalytic activity of the Au@AuAg yolk-shell nanoparticles were investigated based on the model catalytic reaction of hydrogenation reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with superfluous sodium borohydride. The yolk-shell nanostructure had the best catalytic activity when the ratio of Ag to Au was 1:4. The kinetic constant of the reaction, apparent rate constants (K_app) was 0.0072 s⁻¹ when 100 μL of this nanocatalyst was added. This suggests that Au@AuAg Y-SNPs have a promising application in the removal of pollutants from water bodies and environmental remediation.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113828"},"PeriodicalIF":3.8,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659327","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}

{"title":"Defect engineering of anchored on F-doped BNNR surface to enhance low-frequency microwave absorption and achieve exceptional thermal conductivity properties","authors":"Zhen Lv ,&nbsp;Zhongyang Duan ,&nbsp;Ning Jiang ,&nbsp;Ruoxuan Zheng ,&nbsp;Di Yin ,&nbsp;Yufeng Bai ,&nbsp;Tingting Yang ,&nbsp;Tai Peng","doi":"10.1016/j.vacuum.2024.113826","DOIUrl":"10.1016/j.vacuum.2024.113826","url":null,"abstract":"<div><div>The growing demand for AI and smart computing drives the development of compact, lightweight electronic products to mitigate electromagnetic wave (EMW) pollution and thermal management issues. This necessitates materials with enhanced microwave absorption (MA) and optimal thermal conductivity (TC). Herein, we designed and synthesized fluorinated boron nitride nanorods (F-BNNRs) in a single step via plasma ball milling. Ammonium fluoride (NH₄F) served as the fluorinating agent for hexagonal boron nitride nanorods (h-BNNRs). F-BNNR3, with a NH₄F to h-BNNR ratio of 10:1 and 5.84 % fluorine (F) content, exhibits excellent MA, achieving a minimum reflection loss (RLmin) of −68.56 dB at 5.14 GHz with a thickness of 4.32 mm. It also displays a broad MA frequency range (4.6–6.1 GHz, 15.4–17.2 GHz) with significant RL &lt; −10 dB. Additionally, a 0.09 wt% F-BNNR3 solution achieves a thermal conductivity (TC) of 0.95 W m⁻¹K⁻¹, 134 % higher than that of a 0.09 wt% h-BNNR dispersion fluid. Following a post-static treatment, F-BNNR3 attains a TC of 0.86 W m⁻¹K⁻¹, 118 % higher than that of h-BNNR. The incorporation of F into h-BNNRs significantly enhances MA and TC performance, addressing EMW pollution and thermal management challenges in advanced communication technologies utilizing nanofluids.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113826"},"PeriodicalIF":3.8,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657338","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}

{"title":"Development and diagnostic study of the RF nitrogen atom source","authors":"Mengting Li,&nbsp;Xin Xu,&nbsp;Wubin Wu,&nbsp;Shixiang Peng,&nbsp;Weiping Chen,&nbsp;Zhiyi Zhai,&nbsp;Qing Luo,&nbsp;Haiping Peng,&nbsp;Ailin Zhang","doi":"10.1016/j.vacuum.2024.113820","DOIUrl":"10.1016/j.vacuum.2024.113820","url":null,"abstract":"<div><div>With the development of thin film technology, particularly the increasing demand for research on group III nitride materials, the need for N ions has significantly increased. A wider and more efficient RF nitrogen atom source specifically designed for nitride film growth has been developed. To evaluate the nitrogen atom density from the RF nitrogen source, a global model of RF nitrogen gas discharge plasma was created. This model was calibrated by measuring the emission spectrum of RF nitrogen gas discharge, and the relationships between nitrogen atom density and actual working pressure, power, and discharge chamber size were determined. It was found that the nitrogen atom density increases with increasing power and initially increases with pressure before decreasing. Finally, the nitrogen atom density was determined, achieving an 18 % nitrogen atom dissociation rate and a nitrogen atom density of 5 × 10¹²/cm³ at an RF power of 400 W. This density is significantly higher than that of nitrogen ions, indicating that this is a nitrogen atom source with high purity.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113820"},"PeriodicalIF":3.8,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659330","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}

{"title":"Influence of the growth rate during Nb film pulsed laser deposition on the sapphire R-plane","authors":"I.V. Malikov","doi":"10.1016/j.vacuum.2024.113827","DOIUrl":"10.1016/j.vacuum.2024.113827","url":null,"abstract":"<div><div>Optimal conditions for obtaining high quality epitaxial Nb thin films on the monocrystalline sapphire R-plane by pulsed laser deposition in ultrahigh vacuum have been determined. The ratio of room temperature resistance to the residual resistance (RRR) on the substrate temperature has the maximum at about 630 °C. The RRR dependence on the growth rate has the maximum at growth rates of 3–6 nm/min. In epitaxial Nb films, there is a simultaneous increase in the value of RRR and growth misorientation of Nb(001) relatively sapphire R-plane. At the maximum value of RRR, the shapes of Nb X-ray diffraction (XRD) peaks (002) and (011) are symmetrical and close to the Gaussian distribution; at lower RRR values, the shapes of XRD peaks become asymmetrical and cannot be approximated by a single Gaussian distribution, and their shape can be described by the sum of several Gaussian functions. For all obtained films, full width at half maximum (FWHM) of Nb (002) and Nb (011) peaks are 0.2^o and 0.4^о, respectively. FWHM of Nb (002) rocking curves is 0.4^o.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113827"},"PeriodicalIF":3.8,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659418","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}

{"title":"Wide-temperature-range tribological properties of Cu-Ni-Al films with multiple oxidation states","authors":"Ziluo Cheng ,&nbsp;Xiao Wang ,&nbsp;Xiaona Li ,&nbsp;Zhumin Li ,&nbsp;Yinglin Hu ,&nbsp;Qiao Jiang ,&nbsp;Renwei Liu ,&nbsp;Yuandi Hou ,&nbsp;Min Li ,&nbsp;Rui Zheng ,&nbsp;Chuang Dong","doi":"10.1016/j.vacuum.2024.113823","DOIUrl":"10.1016/j.vacuum.2024.113823","url":null,"abstract":"<div><div>High-temperature (HT) apparatus suffer from galling and seizure of contact interface, for which a wear-resistant film is helpful but challenging to design. In this work, the Cu-Ni-Al films prepared by magnetron sputtering provide effective wear-resistant protection for Ni-based superalloy over room temperature (RT) to 800 °C, decreasing the coefficient of friction by 45 %, 30 %, 15 % and wear rate by 97 %, 65 %, 62 % at RT, 400 °C, 600 °C, respectively, and exhibiting especially low wear rate 1.88 × 10⁻⁵mm³N⁻¹m⁻¹ at 800 °C. Layered structure with multiple oxidation states formed during friction is the crucial, with the Cu₂O-rich layer and the CuO layer serving lubrication at RT and HT, respectively. The FCC + L1₂ structure ensures the high-temperature carrying capacity and film-substrate adhesion. AFM investigation exhibits the microscale tribological behavior is relevance with Ni + Al content. This work provides a novel strategy for the design and preparation of wide-temperature-range wear-resistant film.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113823"},"PeriodicalIF":3.8,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659325","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}

{"title":"A new system for sample synthesis, preparation and modification combined with in-situ depth profiling using medium energy ions","authors":"Radek Holeňák ,&nbsp;Dmitrii Moldarev ,&nbsp;Eleni Ntemou ,&nbsp;Theofanis Tsakiris ,&nbsp;Carolin Frank ,&nbsp;Kevin Vomschee ,&nbsp;Svenja Lohmann ,&nbsp;Daniel Primetzhofer","doi":"10.1016/j.vacuum.2024.113824","DOIUrl":"10.1016/j.vacuum.2024.113824","url":null,"abstract":"<div><div>We present equipment for sample synthesis, preparation and modification enabling <em>in-situ</em> studies employing medium energy ion beams at the ion implanter facility of the Tandem Laboratory national research infrastructure at Uppsala University. The integral instrumentation enables controlled thin-film synthesis, modification and characterization applicable to study near-surface processes such as thin-film growth, phase transformation, oxidation, annealing, catalysis or ion implantation. We describe the available instrumentation with its specifications and present four demonstrative experiments with a particular focus on the acquired <em>in-situ</em> capabilities addressing 1) Evaporation and thermal alloying of thin films – nickel silicides 2) Reactive magnetron sputtering and controlled oxidization – photochromic YHO 3) Sputtering and low-energy implantation – hydrogen in tungsten and 4) Surface cleaning of sensitive systems – self-supporting silicon membranes.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113824"},"PeriodicalIF":3.8,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nanocubic transition metal sulfides (FeMn)S2@NC synthesized by MOFs facily for supercapacitors","authors":"Guoqing Feng ,&nbsp;Tiewei Zhao ,&nbsp;Lingling Zhou ,&nbsp;Xin Wang ,&nbsp;Hao Ding ,&nbsp;Feng Jiang ,&nbsp;Huiyu Li ,&nbsp;Yongsheng Liu ,&nbsp;Qing Yu ,&nbsp;Haijing Cao ,&nbsp;Yan Xu ,&nbsp;Yanyan Zhu","doi":"10.1016/j.vacuum.2024.113819","DOIUrl":"10.1016/j.vacuum.2024.113819","url":null,"abstract":"<div><div>Transition metal sulfides have attracted considerable attention as supercapacitor materials due to their favorable electrochemical properties and low cost. However, challenges such as slow electrochemical kinetics and significant volume changes still persist. In this study, (FeMn)S₂@NC nanocubes were synthesized by utilizing MOFs as precursors, employing a solution method to encapsulate Ppy around the periphery, followed by a one-step annealing process. The electrode prepared from (FeMn)S2@NC exhibits a high specific capacitance of 1154 F/g at 1 A/g and retains a specific capacitance of 777 F/g even at a high current density of 5 A/g. After 8000 charge-discharge cycles at 10 A/g, it still maintains a high capacity retention of 94 % and close to 100 % Coulombic efficiency. The (FeMn)S2@NC//AC capacitor exhibite excellent electrochemical performance with good rate capability and practical value 39.73F/g at 1A/g, 38.26F/g at 2A/g, 26.67F/g at 5A/g, 20.53F/g at 7A/g and 14F/g at 10A/g. Electrochemical testing at 5A/g show 93.3 % high capacity retention after 180,000 cycles.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113819"},"PeriodicalIF":3.8,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657370","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}