Evolution of helium bubbles in FeCoNiCr-based high-entropy alloys containing γ′ nanoprecipitates

A series of high-entropy alloys(HEAs) containing nanoprecipitates of varying sizes is successfully prepared by a non-consuming vacuum arc melting method.In order to study the irradiation evolution of helium bubbles in the FeCoNiCrbased HE As with γ' precipitates,these samples are irradiated by 100-keV helium ions with a fluence of 5 × 10^(20) ions/m^(2) at 293 K and 673 K,respectively.And the samples irradiated at room temperature are annealed at different temperatures to examine the diffusion behavior of helium bubbles.Transmission electron microscope(TEM) is employed to characterize the structural morphology of precipitated nanoparticles and the evolution of helium bubbles.Experimental results reveal that nanosized,spherical,dispersed,coherent,and ordered L1_(2)-type Ni_(3)Ti γ' precipitations are introduced into FeCoNiCr(Ni_(3)Ti)_(0.1) HEAs by means of ageing treatments at temperatures between 1073 K and 1123 K.Under the ageing treatment conditions adopted in this work,γ' nanoparticles are precipitated in FeCoNiCr(Ni_(3)Ti)_(0.1) HE As,with average diameters of 15.80 nm,37.09 nm,and 62.50 nm,respectively.The average sizes of helium bubbles observed in samples after 673-K irradiation are 1.46 nm,1.65 nm,and 1.58 nm,respectively.The improvement in the irradiation resistance of FeCoNiCr(Ni_(3)Ti)_(0.1) HEAs is evidenced by the diminution in bubbles size.Furthermore,the FeCoNiCr(Ni_(3)Ti)_(0.1) HEAs containing γ' precipitates of 15.8 nm exhibits the minimum size and density of helium bubbles,which can be ascribed to the considerable helium trapping effects of heterogeneous coherent phase boundaries.Subsequently,annealing experiments conducted after 293-K irradiation indicate that HEAs containing precipitated phases exhibits smaller apparent activation energy(E_(a)) for helium bubbles,resulting in larger helium bubble size.This study provides guidance for improving the irradiation resistance of L1_(2)-strengthened high-entropy alloy.

新型薄膜太阳电池器件:柔性设计与印刷制造

作为新型薄膜太阳电池的代表,有机/钙钛矿太阳电池的光电转换效率在最近十几年内实现了巨大突破.同时,由于其质轻、柔韧性好及可溶液法低成本印刷制备等特点,新型薄膜太阳电池还展现出了应用于柔性器件的潜质,结合与其他功能性柔性电子设备的集成设计,可以满足人们对便携式移动电源和可穿戴设备日益增长的物质需求.作者研究团队近年来围绕柔性薄膜太阳电池集成设计与印刷的关键科学和技术问题,主要针对器件的易脆性和柔性印刷形貌重现性差的问题,开展了系统研究并取得系列创新成果.本专论中重点介绍了在柔性透明电极的设计、柔性界面工程调控、光电转换活性层柔性增韧设计和大面积柔性印刷策略的研究进展,并对柔性薄膜太阳电池组件的发展进行了展望.

Constant current electrodeposition preparation of nickel layer and its mechanical properties in ionic liquid

Smooth and compact nickel layers were successfully prepared in the ionic liquid of 1-butyl-3-methylimidazolium tetrafluoroborate(BMIMBF4)by constant current electrodeposition method.The effects of temperature,additive content,current density,and deposition time on the performance of the nickel layers were systematically analyzed.Scanning electron microscopy(SEM)and X-ray diffraction(XRD)were used to analyze the surface morphology and composition of the nickel layers.Meanwhile,the tensile strengths of the nickel layers were tested by universal tensile testing machine.The results show that different process conditions have a great effect on morphology and performance of the electrodeposited nickel layer.The optimization of process parameters is as follows:BMIMBF4 to ethylene glycol(EG)volume ratio of 2:1,deposition temperature of 120℃,and current density of 1.2 mA·cm^(-2).Current density has a greater influence on the tensile strength of the nickel layer,and the maximum value of tensile strength is 1275 MPa.

Microstructure and properties of electroformed nickel under different waveform conditions

In order to prepare electroformed nickel with excellent properties,the effect of different waveforms on microstructure and mechanical properties was investigated by optical microscopy(OM),X-ray diffraction(XRD) and tensile test,respectively.The results show that the samples are composed of micron columnar grains with high-density nanoscale coherent twin boundaries which are parallel to the growth plane.The tensile strength and elongation display opposite tendency with the increase in current density when direct current(DC) electroforming was applied.However,under the condition of pulse current(unidirectional,bidirectional) electroforming,the change regulation of tensile strength and elongation is close while cathode(peak,positive peak) current density increases.XRD results show that electroformed nickel layers with high purity are all fcc crystal configuration under different conditions of the current waveform.The nickel layers formed under bidirectional pulse current behave superior global performance with tensile strength of 692.0 MPa and elongation of 27.6 %.

Approaches to electrodeposit molybdenum from ionic liquid

Molybdenum is a kind of refractory metal and can hardly be deposited in aqueous solution since it is more likely to form molybdenum oxide rather than elementary Mo,but molten salts and ionic liquid become alternative to obtain Mo layer.This paper shows an available process to obtain metallic state molybdenum deposit from ionic liquid.Mo layer was electrodeposited under constant current in ionic liquid 1-Butyl-3-methylimidazolium tetrafluoroborate(BMIMBF_4).Micromorphology of the electrodeposited Mo layer was observed by scanning electron microscope(SEM),energy dispersive spectroscopy(EDS)and X-ray photoelectron spectroscopy(XPS).Results show that elementary Mo layer was electrodeposited under constant current in ionic liquid BMIMBF4.Properties of the Mo layer are affected significantly by additive ethylene glycol(EG),deposition temperature and current density.By parallel tests taking into consideration of different technical factors,optimized process parameters are obtained as volume ratio of 2:1 in BMIMBF4+EG system,deposition temperature of 150℃and current density of 0.75 mA·cm^(-2).