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Spatial phase structure and oxidation process of Al-W alloy powder with high sphericity

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Journal of materials science & technology 2022年第19期114卷 62-72页

作者： Aobo Hu Shuizhou Cai state key laboratory of material processing and die&mould technology The School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

In this study,Al-30W(wt.%)alloy powder was prepared by Aluminothermic reduction and hightemperature gas atomization.We then studied the phase composition,surface morphology,spatial phase structure,and thermal oxidation process using XRD,SEM/EDS,TEM,DSC,and DTA/TG analysis.The results showed that the Al-30W alloy powder exhibited high sphericity,and the interior presented a special spatial phase structure in which the Al/W amorphous alloy phase and the metastable Al/W intermetallic compound phase were distributed in the pure Al matrix.When the Al-30W alloy powder was stabilized in a vacuum tube furnace,the spatial phase structure of the alloy powder changed,and a small amount of pure Al was embedded in the Al_(12)W matrix.The resulting Al-30W alloy powder products,treated in air at different temperatures,were collected in situ and characterized.The results presented that with an increase in temperature,the types and morphologies of the Al/W intermetallic compounds in the Al-30W alloy powder changed.Furthermore,the Al-30W alloy powder began to undergo intense oxidation reactions at about 900℃,accompanied by a concentrated energy release and rapid weight gain.The volatilization of WO_(3)produced in the oxidation process promoted the complete oxidation of the Al-30W alloy powder,and the Al-30W alloy powder was completely oxidized at 1300℃.At this stage,all W atoms were transformed into gaseous WO_(3),and only a large number of small Al_(2)O_(3)fragments remained in the oxidation product.Thus,the Al-30W alloy powder exhibited excellent thermal reactivity and oxidation integrity,and may offer excellent application prospects in the field of energetic materials.

关键词： Aluminothermic reduction High-temperature gas atomization Al/W amorphous alloy phase Metastable Al/W intermetallic compound phase Thermal oxidation process

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电解液调控实现高电压高镍三元长循环稳定性

science Bulletin 2022年第21期67卷 2225-2234页

作者：程方圆张晓宇魏鹏孙世雄徐月李箐方淳韩建涛黄云辉 state key laboratory of material processing and die&mould technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

为进一步提高高镍三元放电比容量,将充电截止电压从4.3 V提高到4.5/4.7 V,放电比容量可从200 mAh g^(-1)提高到230 mAh g^(-1),这对提高能量密度是非常有利的,但同时会导致界面稳定性进一步降低.本文在商业电解液(1 mol L^(-1)LiPF_(6)/... 详细信息

为进一步提高高镍三元放电比容量,将充电截止电压从4.3 V提高到4.5/4.7 V,放电比容量可从200 mAh g^(-1)提高到230 mAh g^(-1),这对提高能量密度是非常有利的,但同时会导致界面稳定性进一步降低.本文在商业电解液(1 mol L^(-1)LiPF_(6)/EC:DEC=1:1,体积比)基础上,加入双添加剂二氟草酸硼酸锂(LiDFOB)和三甲基硅基磷酸酯(TMSP),一方面形成富含F,B,Si等元素的无机组分界面膜增加高电压下界面稳定性;另一方面,TMSP中的Si-O键具有清除电解液中高腐蚀性HF的作用,以此增加电解液的稳定性.在成膜和除HF的双重作用下,抑制了4.5/4.7 V高截止电压下的界面反应、过渡金属溶出、表面相变及产气.组装的LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)/Li电池在4.5 V下具有800圈的循环寿命,在4.7 V下具有500圈的循环寿命.

关键词：放电比容量循环寿命高电压界面稳定性高镍循环稳定性截止电压能量密度

内膨胀核-缓冲-壳结构Si/EG/C复合材料应用于高性能锂离子电池负极

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science China materials 2022年第11期65卷 2949-2957页

作者：张泽宇孙世雄张稳徐佳王鑫方淳李箐韩建涛 state key laboratory of material processing and die&mould technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

本文采用球磨和喷雾干燥法,制备了类西瓜型可控内膨胀核-缓冲-壳结构Si/电化学剥离石墨烯/C(Si/EG/C)复合材料.在纳米硅和碳壳之间填充了含大量褶皱和空隙的EG,不仅缓冲了Si/EG/C颗粒内部硅的体积变化,还提供了锂离子的快速传输通道.凭... 详细信息

本文采用球磨和喷雾干燥法,制备了类西瓜型可控内膨胀核-缓冲-壳结构Si/电化学剥离石墨烯/C(Si/EG/C)复合材料.在纳米硅和碳壳之间填充了含大量褶皱和空隙的EG,不仅缓冲了Si/EG/C颗粒内部硅的体积变化,还提供了锂离子的快速传输通道.凭借这些优势,核-缓冲-壳结构的Si/EG/C表现出优异的电化学性能.半电池中Si/EG/C负极在100次循环后相对于初始容量没有下降(834 mA h g^(-1)).此外,Si/EG/C//LiCoO_(2)全电池在500次循环后相对于初始放电容量的容量保持率接近100%.这些结果表明Si/EG/C在下一代锂离子电池中具有潜在应用前景.

关键词： silicon graphene lithium-ion battery anode coreshell

Bioinspired Centimeter-scale Sensor Free Obstacle-passing Robots with a Wireless Control System

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Journal of Bionic engineering 2022年第4期19卷 953-964页

作者： Longxin Kan Zhenhua Wu Bo Song Bin Su Yusheng Shi state key laboratory of material processing and die&mould technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074HubeiChina

Obstacle avoidance is of great importance for mobile robots since it provides protection for the robots’safety and ensures their routine operations.Sensors are proven to play an important role in robots obstacle avoidance,and they are useful as well.However,more sensors indicating additional space,larger weight load and more energy consumption.Reducing unnecessary sensors is conducive to the development of mobile robots and remains promising.Here we demonstrate Sensor Free Obstacle-Passing Robots(SFOPRs)inspired by flies using the Obstacle-passing strategy instead of Obstacle avoidance.The ability to autonomously adjust its direction after hitting obstacles and the ability to continuously hit obstacles are 2 key problems that need to be solved to build this robot.Owing to arc-shaped head design and undulating motion behaviors,the robots can autonomously adjust their direction to the outline of obstacles,such as a 90°corner,dispersive irregular obstacles,and even an"S"type channel without the assistance of any sensor.Besides,the caterpillar-like movement enables robots to continuously hit obstacles.Furthermore,collaborative awareness and mutual aid can be realized among two or more prototype robots,indicating simple yet functional units for future swarm robots.This study could provide a new strategy to pursue sensor-free obstacle-passing robots for future swarm robot applications.

关键词： Bioinspired Sensor Obstacle Swarm robots Untethered

Toughening additive manufactured Zr-based bulk metallic glass composites by martensite phase transformation

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Journal of materials science & technology 2024年第3期170卷 95-102页

作者： Pengcheng Zhang Cheng Zhang Jie Pan Di Ouyang Lin Liu state key laboratory of materials processing and die&mould technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

Additive manufacturing technology based on laser powder bed fusion(LPBF)offers a novel approach for fabricating bulk metallic glass(BMG)products without restriction in size and geometry.Nevertheless,the BMGs prepared by LPBF usually suffered from less plasticity and poorer fracture toughness as compared to their cast counterparts due to partial crystallization in heat-affected zones(HAZs).Since crystallization in HAZs is hard to avoid completely in LPBF BMGs,it is desirable to design a suitable alloy system,in which only ductile crystalline phase,instead of brittle intermetallics,is formed in HAZs.This unique structure could effectively increase the toughness/plasticity of the LPBF BMGs.To achieve this goal,a quaternary BMG system with a composition of Zr 47.5 Cu 45.5 Al 5 Co_(2)is adopted and subjected to LPBF.It is found that nearly a single phase of B_(2)-ZrCu is precipitated in HAZs,while a fully amorphous phase is formed in molten pools(MPs).This B_(2)phase reinforced BMG composite exhibits excellent mechanical properties with enhanced plasticity and toughness.Furthermore,it is easy to modulate the mechanical properties by altering the amount of the B_(2)phase via adjusting the laser energy input.Finally,the best combination of strength,plasticity,and notch toughness is obtained in the BMG composite containing 27.4%B_(2)phase and 72.6%amorphous phase,which exhibits yield strength(σ_(s))of 1423 MPa,plastic strain(ε_(p))of 4.65%,and notch toughness(K_(q))of 53.9 MPa m 1/2.Furthermore,a notable strain-hardening is also observed.The improvement of plasticity/toughness and appearance of strain-hardening behavior are mainly due to the martensite phase transformation from the B_(2)phase to the Cm phase during plastic deformation(i.e.,the phase transformation-induced plasticity effect).The current work provides a guide for making advanced BMGs and BMG composites by additive manufacturing.

关键词： Laser powder bed fusion Bulk metallic glass composites Phase transformation-induced plasticity Deformation mechanism

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类沸石结构分子:极具潜力的二维介电材料

science China materials 2023年第1期66卷 233-240页

作者：刘立昕李鹏雨赵英鹤宋海洋刘腾李会巧翟天佑 state key laboratory of materials processing and die&mould technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

二维半导体材料的出现为新一代半导体器件的开发与摩尔定律的延续带来了前所未有的机遇.然而,缺乏合适的介电材料使二维半导体的实际应用严重受阻.在本文中,我们采用理论结合实验的研究方法,展示了类沸石结构分子(ZLMs)在用作二维介电... 详细信息

二维半导体材料的出现为新一代半导体器件的开发与摩尔定律的延续带来了前所未有的机遇.然而,缺乏合适的介电材料使二维半导体的实际应用严重受阻.在本文中,我们采用理论结合实验的研究方法,展示了类沸石结构分子(ZLMs)在用作二维介电材料方面极具潜力.具体而言,ZLMs具有与二氧化硅相当的带隙与介电常数,且ZLMs与二维半导体材料通过范德华力进行连接,形成了理想的接触界面.此外,ZLMs具有良好的环境稳定性.本文提出了一类全新的范德华介电材料,对二维半导体领域意义重大.

关键词：介电材料半导体器件摩尔定律范德华力二维半导体接触界面介电常数

具有亚2-nm沟道长度的二维垂直p-n结二极管

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science China materials 2023年第9期66卷 3637-3643页

作者：王浩云宋星宇李东燕李泽鑫许翔陈韵欣刘鹏斌周兴翟天佑 state key laboratory of materials processing and die&mould technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

尺寸极限微缩的p-n结二极管对互补金属氧化物半导体(CMOS)集成电路的发展至关重要.然而,由于界面缺陷和短沟道效应,实现5 nm以下沟道长度的p-n结二极管仍然面临着巨大的挑战.本文展示了1.9 nm沟道的WSe_(2)/WS_(2)垂直p-n结二极管,实现... 详细信息

尺寸极限微缩的p-n结二极管对互补金属氧化物半导体(CMOS)集成电路的发展至关重要.然而,由于界面缺陷和短沟道效应,实现5 nm以下沟道长度的p-n结二极管仍然面临着巨大的挑战.本文展示了1.9 nm沟道的WSe_(2)/WS_(2)垂直p-n结二极管,实现了~8×10^(3)的高开关比和~17的整流比.此外,沟道长度为4.7 nm的器件具有~10^(4)的高开关比和~10^(3)的整流比.其高性能源于无肖特基势垒的接触导致的理想带排列,以及无缺陷的全范德华(vdW)界面导致的低隧穿电流和小的费米钉扎效应.因此,我们实现了p-n二极管的本征性能.该策略也可以扩展到其他的p-n结,如WSe_(2)/MoSe_(2)和WSe_(2)/MoS_(2),这表明我们的策略具有普适性.该策略为电子器件尺寸微缩和集成电路的进一步发展提供了新的思路.

关键词：沟道长度肖特基势垒短沟道效应隧穿电流开关比集成电路二极管界面缺陷

钠离子高电压正极Na_(0.7)Ni_(0.35)Sn_(0.65)O_(2)材料在空气中的劣化及修复机理

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science China materials 2023年第1期66卷 88-96页

作者：张瑞旺梁嘉宁曾诚陈佳俊马颖翟天佑李会巧 state key laboratory of materials processing and die&mould technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

层状过渡金属氧化物因其高比容量、环境友好、易于规模化合成等优点,一直以来被认为是钠离子电池最有潜力的正极候选材料.作为一种新报道的层状材料,O3-Na_(0.7)Ni_(0.35)Sn_(0.65)O_(2)的平台电位高达3.7V,是目前层状正极材料中平均电... 详细信息

层状过渡金属氧化物因其高比容量、环境友好、易于规模化合成等优点,一直以来被认为是钠离子电池最有潜力的正极候选材料.作为一种新报道的层状材料,O3-Na_(0.7)Ni_(0.35)Sn_(0.65)O_(2)的平台电位高达3.7V,是目前层状正极材料中平均电压的最高值,但关于其空气稳定性的研究还未见报道.本文详细考察了层状Na_(0.7)Ni_(0.35)Sn_(0.65)O_(2)材料在空气中的劣化机制,发现该材料对空气非常敏感,在25℃,80%相对湿度的条件下仅过4小时就完全转化为水化相.进一步通过复烧法对其进行修复,发现因空气暴露而脱出的Na+是否可以重新嵌入到晶格中是结构和电化学性能恢复的关键.本工作揭示了Na_(0.7)Ni_(0.35)Sn_(0.65)O_(2)材料在空气中的劣化过程和修复机理,为该材料的应用及复烧工艺的深层理解提供了有价值的参考.

关键词：钠离子电池层状正极材料层状材料过渡金属氧化物电化学性能空气稳定性高电压平均电压

Effects of mechanical vibration on filling and solidification behavior, microstructure and performance of Al/Mg bimetal by lost foam compound casting

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China Foundry 2023年第6期20卷 469-479页

作者： Guang-yu Li Feng Guan Wen-ming Jiang Yuan-cai Xu Zheng Zhang Zi-tian Fan state key laboratory of materials processing and die&mould technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

Al/Mg bimetal was prepared by lost foam solid-liquid compound casting,and the effects of mechanical vibration on the filling and solidification behavior,microstructure and performance of the bimetal were investigated.Results show that the mechanical vibration has a remarkable influence on the filling and solidification processes.It is found that after mechanical vibration,the filling rate increases and the filling rate at different times is more uniform than that without vibration.In addition,the mechanical vibration also increases the wettability between liquid AZ91D and A356 inlays.The mechanical vibration reduces the horizontal and vertical temperature gradient of the casting and makes the temperature distribution of the whole casting more uniform.Compared to the Al/Mg bimetal without vibration,the shear strength is improved by 39.76%after the mechanical vibration is applied,due to the decrease of the inclusions and Al_(12)Mg_(17) dendrites,and the refinement and uniform distribution of the Mg_(2)Si particles in the interface of the Al/Mg bimetal.

关键词： lost foam casting filling and solidification processes Al/Mg bimetal mechanical vibration microstructure mechanical properties