过共晶球墨铸铁中石墨球周围奥氏体壳的形成机制

有用着色腐蚀技术，可清晰地显示出过共晶球墨铸铁中的高温凝固组织，观察分析了石墨球周围奥氏体壳（奥氏体壳是奥氏体枝晶的一部分）的形成机制。结果表明，初生枝晶和晕圈枝晶交替生长，促成石墨球周围奥氏体壳的形成；奥氏体以石墨生长面（0001）为衬底形核、生长，在初生石墨球周围形成环状封闭奥氏体壳；共晶前期石墨球在枝晶臂间或框架中形核、生长、尔后为枝晶高次臂所包围，形成封闭或不封闭的框架奥氏体壳。共晶后期石墨球不形成奥氏体壳。     

Ultrastructure of sensilla on the maxillary and labial palps of the adult Xylotrechus grayii (Coleoptera: Cerambycidae)

The longhorn beetle, Xylotrechus grayii (White, 1855), is a serious woodborer pest of many economic and medicinal plants. The maxillary and labial palps of X. grayii adults are strongly involved in mating and host selection behaviors. To further develop control strategies of the pest, sensilla on the palps were studied with scanning and transmission electron microscopy. Five types of sensilla (nine subtypes) were identified: sensilla styloconica (four subtypes, Sty1‐4), sensilla chaetica (2 subtypes, SC1‐2), sensilla digitiformia (Di), sensilla basiconica (Ba), and Böhm sensilla (Bm). Sty and Ba have dendrites and wall pores. SC2 has a tubular body. Di exist only on the terminal segment of the maxillary palp. Sty numbers are the highest in both palps, followed by SC. The number of sensilla in the maxillary palp is significantly higher than that in the labial palp. There are no significant sexual differences in sensilla types, characteristics, distribution, and quantity in the maxillary or labial palps, except for the number of SC sensilla on the maxillary palp. Sensilla functions were compared with correlative sensilla in previous studies. Sty may be sense gustation and olfaction stimulation, while SC are mechanoreceptors. Ba are likely thermo‐ and hygroreceptors. The phylliform depression area formed by Di may exert multiple functions. Bm may sense palp position and movement. These results contribute to the study of the electrophysiology and behavior mechanisms of X. grayii.     

CrFeMnVCu系高熵合金的微观组织和性能

本文在CrMnFeV四元合金的基础上添加奥氏体形成元素Cu元素,同时降低Mn元素含量,并采用电弧熔炼+铜模吸铸工艺制备了CrMnFeVCu系高熵合金,并系统研究了合金的成分设计和元素配比对高熵合金组织和性能的影响机理。结果表明,CrMnFeV四元合金由BCC固溶体和极少量B2颗粒组成,CrMnxFeVCu0.2x （x= 0.3、0.5、0.7、1）合金由BCC结构的树枝晶相和FCC结构的枝晶间相组成,且随着Cu含量的增加,FCC枝晶间相的体积分数和尺寸逐渐增大,相形态从颗粒状逐渐转变为长条状和块状。压缩试验表明,CrMn0.3FeVCu0.06合金的屈服强度最高（1273 MPa）,且塑性优异（εf = 50.7%）,随着Cu含量的增加,合金的力学性能逐渐降低,这主要归因于CrMnxFeVCu0.2x合金中主要的强化机制是位错强化和第二相强化,而FCC相尺寸的增大会降低第二相强化的效果。     

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 对27SiMn钢连铸圆坯中心星形裂纹产生原因进行了研究。采用金相显微镜、扫描电子显微镜及X射线能谱仪对中心星形裂纹的宏观和微观特征、化学成分、显微组织进行分析,结果表明：中心星形裂纹是连铸坯最后凝固钢液形成的卵形树枝晶在张应力作用下形成的空隙。     

High voltage preparation, characterization, and optical properties of silver dendrites in PVA matrix

In this paper, we present a room-temperature synthesis of silver dendrites in a poly(vinyl alcohol) (PVA)-Ag composite system with the assistance of high voltage. In the silver dendrites, the nanounits are platelike,thus the surface plasmon absorption bands of silver dendrites are tuned from visible to～800 nm, which is due to the template function of PVA and the assistance of high voltage. Scanning electron microscope (SEM), X-ray diffraction (XRD), and energy dispersive X-ray (EDX) data confirm that the structures are crystalline silver embedded in PVA. The absorption results indicate that the ratio of PVA and Ag do not influence the position but the intensity of the near-infrared (NIR) absorption. This material has potential use in the field of bio-application and infrared sensors.     

Spontaneously Splitting Copper Nanowires into Quantum Dots on Graphdiyne for Suppressing Lithium Dendrites

As an emerging carbon allotrope, the controllable growth of graphdiyne has been an important means to explore its unique scientific properties and applications. In this work, the effect of the crystal structure of copper (Cu) on the growth of graphdiyne is systematically studied. It is found that the crystal boundaries are the origin of the reaction activity. The polycrystalline Cu nanowire with many crystal boundaries is spontaneously split into Cu quantum dots (about 3 nm) by the grown graphdiyne. These Cu quantum dots are uniformly dispersed on the graphdiyne, and they block the long-range ordered growth of the graphdiyne. These Cu quantum dots in situ supported on graphdiyne demonstrate high efficiency in inhibiting the growth of lithium dendrites in lithium metal batteries. Based on this interesting finding, the Cu quantum dots anchored on the all-carbon graphdiyne can be prepared on a large scale, and unique applications of Cu quantum dots in electrochemical fields can be implemented.     

Horizontal Growth of Lithium on Parallelly Aligned MXene Layers towards Dendrite‐Free Metallic Lithium Anodes

Although metallic lithium is an extremely promising anode for lithium‐based batteries due to its high theoretical capacity, the uncontrollable growth of lithium dendrites, in particular under deep stripping and plating, have stagnated its application. It is demonstrated that parallelly aligned MXene (Ti₃C₂T_x ) layers enable the efficient guiding of lithium nucleation and growth on the surface of 2D MXene nanosheets, giving rise to horizontal‐growth lithium anodes. Moreover, the inherent fluorine terminations in MXene afford a uniform and durable solid electrolyte interface with lithium fluoride at the anode/electrolyte interface, efficiently regulating electromigration of lithium ions. Thus, a dendrite‐free lithium anode with a long cycle life up to 900 h and excellent deep stripping–plating capabilities up to 35 mAh cm^?2 is achieved, which can further serve as an anode for a lithium metal battery, exhibiting high cycle stability up to 1000 cycles.     

Simultaneously Regulating the Ion Distribution and Electric Field to Achieve Dendrite‐Free Zn Anode

Rechargeable aqueous Zn‐ion batteries are promising candidates for large‐scale energy storage systems. However, there are many unresolved problems in commercial Zn foils such as dendrite growth and structural collapse. Herein, Cu mesh modified with CuO nanowires is constructed to simultaneously coordinate the ion distribution and electric field during Zn nucleation and growth. Owing to the improved uniformity of Zn plating and the confined Zn growth in the 3D framework, the prepared Zn anodes can be operated steadily in symmetrical cells for 340 h with a low voltage hysteresis (20 mV). This work can provide a new strategy to design the dendrite‐free Zn anodes for practical application.     

Component‐Interaction Reinforced Quasi‐Solid Electrolyte with Multifunctionality for Flexible Li–O2 Battery with Superior Safety under Extreme Conditions

High‐performance flexible lithium–oxygen (Li–O₂) batteries with excellent safety and stability are urgently required due to the rapid development of flexible and wearable devices. Herein, based on an integrated solid‐state design by taking advantage of component‐interaction between poly(vinylidene fluoride‐co‐hexafluoropropylene) and nanofumed silica in polymer matrix, a stable quasi‐solid‐state electrolyte (PS‐QSE) for the Li–O₂ battery is proposed. The as‐assembled Li–O₂ battery containing the PS‐QSE exhibits effectively improved anodic reversibility (over 200 cycles, 850 h) and cycling stability of the battery (89 cycles, nearly 900 h). The improvement is attributed to the stability of the PS‐QSE (including electrochemical, chemical, and mechanical stability), as well as the effective protection of lithium anode from aggressive soluble intermediates generated in cathode. Furthermore, it is demonstrated that the interaction among the components plays a pivotal role in modulating the Li‐ion conducting mechanism in the as‐prepared PS‐QSE. Moreover, the pouch‐type PS‐QSE based Li–O₂ battery also shows wonderful flexibility, tolerating various deformations thanks to its integrated solid‐state design. Furthermore, holes can be punched through the Li–O₂ battery, and it can even be cut into any desired shape, demonstrating exceptional safety. Thus, this type of battery has the potential to meet the demands of tailorability and comformability in flexible and wearable electronics.