BackgroundCu-W composites are widely used in electric power, electronics, and plastic forming owing to the excellent electrical and thermal conductivities of copper combined with the outstanding ...strength and thermal properties of tungsten.PurposeThis study aims to investigate the extension of the solid solubility of the Cu-W immiscible system under high current pulsed electron beam (HCPEB) irradiation.MethodsFirst of all, the Cu-15W powder mixture was sintered by vacuum at 850 ℃ after ball milling for 5 h to prepare the Cu-W composites. After polishing, the Cu-W composites was exposed by a HOPE-1 type HCPEB device with 1, 5, 10 and 15 pulses, respectively. Then, Rigaku D/Max-2500/pc X-ray diffractometer (XRD) was used to analyze the phase constitutes of the milling powder, sintered samples and irradiated samples. The surface morphology was observed by JEOL JSM-7001F field emission scanning electron microscope (SEM). The energy dispersive spectrometer (EDS) in SEM was used for the examination of micro-region c
TL1; Cu-W复合材料由于兼具铜的导热性与导电性以及钨的高强度与高温性能而被广泛应用于电力、电子、塑性成形等众多领域.本研究利用电子束快速凝固的特点,提高Cu-W互不相溶合金体系的固溶度,以改善材料性能.采用粉末冶金法制备Cu-W复合材料,并利用强流脉冲电子束(High Current Pulsed Electron ...Beam,HCPEB)技术对其进行表面改性,研究不同处理工艺参数对样品固溶度和表面硬度的影响.结果表明:在球磨过程中形成了Cu(W)固溶体,球磨5 h时粉末固溶度的提升最为明显.差示扫描量热分析仪(Differential Scanning Calorimeter,DSC)表明,固溶体在烧结的加热过程中会发生脱溶反应.利用强流脉冲电子束对烧结试样表面进行辐照处理,结果表明:HCPEB辐照可有效提高Cu-W互不固溶合金体系的固溶度,致使辐照表面形成Cu(W)过饱和固溶体合金化层.W在Cu基体中的固溶度随辐照次数而增加,10次辐照后Cu(W)固溶体中溶质元素(W)的重量百分比达到了1.63％;辐照表面的硬度随着固溶度的增加而显著增加,固溶强化和弥散强化效应是辐照表面性能改善的根本原因.
In this investigation, chromium (Cr) was adopted as an alloying element on a nickel substrate, and the alloying process was materialized via high-current pulsed electron beam (HCPEB) irradiation. ...X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were also conducted for microstructure characterization. The results showed that after HCPEB irradiation a nanocrystalline Cr-Ni alloying layer was formed and numerous dislocations were generated, resulting in a great deal of diffusion paths for Cr elements. Moreover, properties including hardness, wear and electrochemical performance were significantly improved after HCPEB irradiation, which was mainly due to the formation of the nanocrystalline Cr⁻Ni alloying layer. In addition, each strengthening mechanism that contributed to the hardness of the HCPEB-irradiated sample was mathematically analyzed, and solid solution strengthening was found to be of great importance.
Although semiconducting ferromagnetism has been experimentally discovered in two-dimensional (2D) crystals, the spin coupling is still quite weak, which leads to a rather low Curie temperature (T C). ...Thus, it is quite confused whether the ferromagnetism in semiconductors can survive under room temperature. Here, through isovalent alloying, we propose that the semiconducting ferromagnetism of 2D MnS2 can be significantly enhanced with T C improved higher than room temperature. Based on first-principles calculations, we systematically studied the properties of original MnS2 and the isovalent alloying systems Mn x Re1–x S2. The spin coupling is significantly enhanced by introducing Mn–Re virtual bonds, and the highest T C of the system reaches 360 K. Besides this, a tensile strain will further enhance the ferromagnetic couplings as well as the uniaxial magnetic anisotropy, which is important for the stabilization of long-range ferromagnetic order in a 2D system. Our results not only broaden the family of 2D ferromagnetic semiconductors but also provide the direct clues to prepare such high-temperature magnetic materials for promising applications in spintronics.
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IJS, KILJ, NUK, PNG, UL, UM
Atomically thin two-dimensional (2D) crystals have piqued the curiosity of researchers due to their unique features and potential applications, such as catalysis and ion batteries. One essential and ...desirable aspect of 2D materials is that they have a large photoreactive contact surface for optical absorption. Here, a 2D crystal is proposed that possesses a moderate adjustable indirect band gap of 1.95 eV (HSE06) and exhibits ultrahigh visible light harvesting with a absorption coefficient of up to 108 cm−1 in the ∼380 to 800 nm range of the visible light spectrum. Besides that, the indirect band gap can be converted to a direct one under biaxial strain. By means of density functional theory, the 2D Al2Te5 monolayer displays great stability and promise of experimental fabrication. These advantages will provide considerable application potential for future photovoltaics (PV) devices.
Atomically thin two-dimensional (2D) crystals have piqued the curiosity of researchers due to their unique features and potential applications, such as catalysis and ion batteries. One essential and ...desirable aspect of 2D materials is that they have a large photoreactive contact surface for optical absorption. Here, a 2D crystal is proposed that possesses a moderate adjustable indirect band gap of 1.95 eV (HSE06) and exhibits ultrahigh visible light harvesting with a absorption coefficient of up to 10
cm
in the ∼380 to 800 nm range of the visible light spectrum. Besides that, the indirect band gap can be converted to a direct one under biaxial strain. By means of density functional theory, the 2D Al
Te
monolayer displays great stability and promise of experimental fabrication. These advantages will provide considerable application potential for future photovoltaics (PV) devices.
Atomically thin two-dimensional (2D) crystals have piqued the curiosity of researchers due to their unique features and potential applications, such as catalysis and ion batteries. One essential and ...desirable aspect of 2D materials is that they have a large photoreactive contact surface for optical absorption. Here, a 2D crystal is proposed that possesses a moderate adjustable indirect band gap of 1.95 eV (HSE06) and exhibits ultrahigh visible light harvesting with a absorption coefficient of up to 10
8
cm
−1
in the ∼380 to 800 nm range of the visible light spectrum. Besides that, the indirect band gap can be converted to a direct one under biaxial strain. By means of density functional theory, the 2D Al
2
Te
5
monolayer displays great stability and promise of experimental fabrication. These advantages will provide considerable application potential for future photovoltaics (PV) devices.
Atomically thin two-dimensional (2D) crystals have piqued the curiosity of researchers due to their unique features and potential applications, such as catalysis and ion batteries.
In this work, the microstructure and optical properties of the Mo/Si multilayers mirror for the space extreme-ultraviolet solar telescope before and after 100 keV proton irradiation have been ...investigated. EUV/soft X-ray reflectometer （EXRR） results showed that, after proton irradiation, the reflectivity of the Mo/Si multilayer decreased from 12.20% to 8.34% and the center wavelength revealed red shift of 0.38 nm, as compared with those before proton irradiation. High-resolution transmission electron microscopy （HRTEM） observations revealed the presence of MoSi2, Mo3Si and Mo5Si3 in Mo-on-Si interlayers before irradiation. The preferred orientation such as MoSi2 with （101） texture and Mo5Si3 with （310） texture was formed in Mo-on-Si interlayers after proton irradiation, which led to the increase of thickness in the interlayers. It is suggested that the changes of microstructures in Mo/Si multilayers under proton irradiation could cause optical properties degradation.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In this paper, a new TiBN micro-nano powder was synthesized by boronizing sintering method. The TiBN powder exhibits specific micro-nano composite structure, which is composed of TiBN crystal and ...amorphous layer of nanometer size. The amorphous structure mostly distributes along particle boundary with minimum thickness of 2 nm. The TiBN powder shows combined ceramic and metallic properties with an exordinary electrical conductivity, having an electrical resistivity of 2.655 × 10−5 Ωm (much better than that of TiN, TiCN, TiB2 and TiC). Solid dissolution of B into TiN decreases the number electron of the system and pull down the Fermi level, making the electron present a quasi-linear dispersion contributing to excellent electrical conductivity of TiBN powder. Such TiBN can be used as conductive phase and reinforcing phase in electrical contact materials. Additionally, the TiBN significantly improve the arc erosion resistance of copper-based electrical contact without reducing the electrical conductivity of copper. When the reinforced phase content was 2.5 wt%, the resistivity of Cu/TiBN was 0.26 × 10−6 Ωm, which was only 20.5% that of Cu/TiN. TiO2, Ti3O5, B2O3 and N2 were formed on the surface of Cu/TiBN samples during arc erosion. Such products can significantly enhance the arc erosion resistance of Cu/TiBN electrical contact materials. This TiBN powder synthesis route can be used to prepare bulk materials in engineering materials industry. In addition, it has attractive research value and broad application prospects in photovoltaic cells and energy storage collector applications including lithium batteries, supercapacitors, and fuel cells.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Mo/Si multilayers were fabricated by using magnetron sputtering method at different background pressures：6×10-5 Torr,3×10-5 Torr,and 3×10-6 Torr.The reflectivity of the Mo/Si multilayers increased ...from 1.93% to 16.63%,and the center wavelength revealed a blue shift to 0.12 nm with the decrease of background pressure.Grazing incident X-ray diffraction（GIXRD） indicated that multilayers fabricated at high background pressure possessed better periodic structure and thinner Mo-on-Si interlayers.Low crystallization degree in（110） preferred the orientation of Mo layers and serious interdiffusion in the Mo/Si multilayers fabricated at low background pressure were observed by transmission electron microscopy（TEM）.According to quantitative analysis of microstructural parameters,the Mo layers thickness and thickness ratio of Mo/Si multilayers both decreased and approached the design value gradually by the decrease of background pressure.In addition,the thicknesses of Mo-on-Si and Si-on-Mo interlayers were 1.17 nm and 0.85 nm respectively.It is suggested that the influence of background pressures on the microstructure has a critical role in determining the optical properties of Mo/Si multilayers.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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