检索结果-南通市图书馆

Effect of trace tungsten on the microstructure of TiAl alloys containing Nb and B

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2007年第4期26卷 323-329页

作者： LIU Bin LIU Yong huang Lan huang Jinsong ZHANG Yonghong huang boyun State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China

New TiAl alloys, containing 45 at.% A1, 7 at.% Nb, x at.% W, and 0.15 at.% B （x = 0, 0.2, 0.4, and 0.7） were prepared by arc melting and drop casting consequently. Using optical microscopy, scanning electron microscopy （SEM）, and electron superprobe technologies, the effects of tungsten on the microstructural evolution of the TiA1 alloys, including the colony size and lamellar spacing, were analyzed. It was found that cellular structures and dendrites were formed in the as-cast TiA1 alloys, and heavy metals, such as niobium and tungsten, tend to segregate strongly at the interface of the cellular structures and dendrites. Trace tungsten can effectively impede the grain growth and narrow the interlamellar spacing. 0.4 at.% tungsten is more effective in refuting the microstructure of the TiAI alloys.

关键词： TiAl alloys tungsten grain size β(B2)phase microstructure

Hierarchically porous Ni monolith@branch-structured NiCo2O4 for high energy density supercapacitors

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2016年第3期26卷 276-282页

作者： Mengjie Xu Rongjun Xu Ying Zhao Libao Chen boyun huang Weifeng Wei State Key Laboratory of Powder Metallurgy Central South University

A variety of NiCo2O4nanostrucutures ranging from nanowire to nanoplate and branched structures were successfully prepared via a simple hydrothermal process. The experimental results show that NiCo2O4with branched structures possesses the best overall electrochemical performance. The improvement of energy density was explored in terms of hierarchically three-dimensional（3D） metal substrates and a high specific area capacitance, and area energy density is obtained with hierarchically porous Ni monolith synthesized through a controlled combustion procedure.

关键词： Supercapacitors NiCo2O4 nanostructures Porous Ni monolith Energy density

Engineering of yolk-shelled FeSe_(2)@nitrogen-doped carbon as advanced cathode for potassium-ion batteries

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2021年第11期32卷 3601-3606页

作者： Chang Liu Yujie Li Yanhong Feng Sen Zhang Di Lu boyun huang Tao Peng Weiwei Sun College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China School of Physics and Electronics Hunan UniversityChangsha 410082China School of Physics and Electronic Engineering Xinyang Normal UniversityXinyang 464000China

Potassium-ion batteries(KIBs)have become the most promising alternative to lithium-ion batteries for large-scale energy storage system due to their abundance and low ***,previous reports focused on the intercalation-type cathode materials usually showed an inferior capacity,together with a poor cyclic life caused by the repetitive intercalation of large-size K-ions,which hinders their practical ***,we combine the strategies of carbon coating,template etching and hydrothermal selenization to prepare yolk-shelled FeSe_(2)@N-doped carbon nanoboxes(FeSe_(2)@C NBs),where the inner highly-crystalline FeSe_(2)clusters are completely surrounded by the self-supported carbon *** integrated and highly conductive carbon shell not only provides a fast electron/ion diffusion channel,but also prevents the agglomeration of FeSe_(2)*** evaluated as a conversion-type cathode material for KIBs,the FeSe_(2)@C NBs electrode delivers a relatively high specific capacity of 257 mAh/g at 100 mA/g and potential platform of about 1.6 V,which endow a high energy density of about 411 Wh/*** importantly,by designing a robust host with large internal void space to accommodate the volumetric variation of the inner FeSe_(2)clusters,the battery based on FeSe_(2)@C NBs exhibits ultra-long cycle ***,even after 700 cycles at 100 mA/g,a capacity of 221 mAh/g along with an average fading rate of only 0.02%can be retained,which achieves the optimal balance of high specific capacity and long-cycle stability.

关键词： Potassium battery Yolk-shell structure FeSe_(2) Conversion-type cathode High energy density

在线全文

学校读者我要写书评

暂无评论

细晶TiAl基铸造合金的制备及其凝固特征

稀有金属材料与工程 2009年第6期38卷 982-986页

作者：肖代红黄伯云中南大学粉末冶金国家重点实验室湖南长沙410083

采用非自耗电弧熔炼铸造方法,制备了Ti-Al-Nb基铸造合金。通过X射线衍射、金相观察、扫描电镜及透射电镜等实验方法,研究了Al含量对基体合金显微组织与凝固特征的影响。结果表明,适当降低铸造合金中铝的含量,能制备出晶粒细小的Ti-44Al-... 详细信息

采用非自耗电弧熔炼铸造方法,制备了Ti-Al-Nb基铸造合金。通过X射线衍射、金相观察、扫描电镜及透射电镜等实验方法,研究了Al含量对基体合金显微组织与凝固特征的影响。结果表明,适当降低铸造合金中铝的含量,能制备出晶粒细小的Ti-44Al-2Nb-1Cr-1W-1B合金,其平均晶粒尺寸为50μm。细晶TiAl基铸态合金中β相与γ相存在'伴生'现象;同时,该合金中一定量β相稳定元素W和Nb的加入,使高温β相得以在凝固过程中保留到室温,这种少量β相的存在也限制了α相晶粒的长大。

关键词：钛铝基合金制备显微组织凝固特征

在线全文

学校读者我要写书评

暂无评论

原位合成钛基复合材料的最新进展

粉末冶金技术 2008年第3期26卷 217-223,229页

作者：肖代红黄伯云中南大学粉末冶金国家重点实验室长沙410083

原位合成钛基复合材料以其高比强、高比模量引起了人们的广泛关注,尤其是如何提高其高温性能成为近年来钛基复合材料研究的热点。本文综合评述了原位合成钛基复合材料的最新进展,包括各种制备方法、增强体与钛基体的选择、各种增强体的... 详细信息

原位合成钛基复合材料以其高比强、高比模量引起了人们的广泛关注,尤其是如何提高其高温性能成为近年来钛基复合材料研究的热点。本文综合评述了原位合成钛基复合材料的最新进展,包括各种制备方法、增强体与钛基体的选择、各种增强体的反应体系以及原位合成钛基复合材料显微组织与力学性能,指出了原位合成钛基复合材料今后的发展方向。

关键词：钛基复合材料原位合成制备方法力学性能

C/C-SiC复合材料的导热性能及其影响因素

在线全文

学校读者我要写书评

暂无评论

中南大学学报（自然科学版） 2013年第1期44卷 40-45页

作者：李专肖鹏熊翔黄伯云中南大学粉末冶金国家重点实验室湖南长沙410083

以炭纤维针刺毡为预制体,采用化学气相渗透法和熔融渗硅法相结合制得C/C-SiC复合材料;研究C/C-SiC材料在室温至1 300℃之间的导热性能以及预制体结构、基体炭结构和石墨化处理对其热扩散率的影响。研究结果表明:C/C-SiC材料的比热容随... 详细信息

以炭纤维针刺毡为预制体,采用化学气相渗透法和熔融渗硅法相结合制得C/C-SiC复合材料;研究C/C-SiC材料在室温至1 300℃之间的导热性能以及预制体结构、基体炭结构和石墨化处理对其热扩散率的影响。研究结果表明:C/C-SiC材料的比热容随着温度的升高不断增大,在700℃时达到最大值2.18 J/(g·K),随后降至1 300℃时的0.57 J/(g·K),其导热系数在1 300℃时为3.95 W/(m.K);C/C-SiC材料的热扩散率在室温时为0.12 cm2/s,随着温度的升高不断降低并趋于常量,平行摩擦面方向的热扩散率明显比垂直于摩擦面方向的大;以全网胎为预制体的C/C-SiC材料其垂直和平行摩擦面的热扩散率相当,树脂炭质量分数增大及石墨化处理均可显著提高C/C-SiC材料的热扩散率。

关键词： C C-SiC复合材料导热系数熔融渗硅炭纤维

First-principles study on the lattice stability of elemental Co,Rh,and Ir in the ⅧB group

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2009年第3期28卷 212-220页

作者： TAO Huijina YIN Jian YIN Zhimin ZHANG Chuangfu LI Jie huang boyun School of Materials Science and Engineering Central South University Changsha 410083 China School of Metallurgical Science and Engineering Central South University Changsha 410083 China Key Lab of Nonferrous Materials Science and Engineering Ministry of Education of China Central South University Changsha 410083 China

Lattice constants, total energies, and densities of state of transition metals Co, Rh, and Ir in the VⅢB group with different crystalline structures were calculated via generalized gradient approximation （GGA） of the total energy plane wave pseudopotential method in first-principles. The lattice stabilities of Rh and Ir are ΔG^ bcc-hcp 〉 Δ G^fcc-hcp 〉 0, agreeing well with those of the projector augmented wave method in first-principles and the CALPHAD method in spite of elemental Co. Analyses of the electronic structures to lattice stability show that crystalline Rh and Ir with fcc structures have the obvious characteristic of a stable phase, agreeing with the results of total energy calculations. Analyses of atomic populations show that the transition rate of electrons from the s state to the p or d state for hcp, fcc, and bcc crystals of Co and Rh increases with the elemental period number to form a stronger cohesion, a higher cohesive energy, or a more stable lattice between atoms in heavier metals.

关键词： Co Rh Ir lattice stability plane wave pseudopotential method generalized gradient approximation

GOVERNMENT WORK UNDER MICROSCOPE

在线全文

学校读者我要写书评

暂无评论

Beijing Review 2014年第11期57卷 12-15页

作者： Xu Shousheng huang boyun huang Taiyan Nyima Zhoima Li Ruogu Chen Dongzheng Du Ying

Chinese Premier Li Keqiang delivered the government＇s annual work report during the opening meeting of the Second Session of the 12th National People＇s Congress （NPC）-China＇s top legislature-in Beijing on March 5. Beijing Review reporters Zhou Xiaoyan, Deng Yaqing, Zeng Wenhui, Miao Xiaoyang and Hou Weili spoke to NPC deputies and members of the 12th National Committee of the Chinese People＇s Political Consultative Conference （CPPCC）-China＇s top political advisory body-to hear their viewpoints on topics covered in the report. Edited Excerpts follow：

关键词：中国人民政治协商会议显微镜全国人民代表大会人大代表咨询机构总理李委员会北京

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

钨合金的形变强化新工艺与断裂机制研究

硬质合金 2007年第2期24卷 119-123页

作者：范景莲黄伯云中南大学粉末冶金国家重点实验室湖南长沙410083

形变强化是提高钨合金性能的必要手段,是制备拉伸强度大于1200MPa的钨合金穿甲弹弹芯材料的主要途径。形变强化主要通过旋锻、静液挤压、热挤压或其它热机械加工复合变形技术实现。形变强化的机制主要是大变形使钨晶粒呈纤维状。本文综... 详细信息

形变强化是提高钨合金性能的必要手段,是制备拉伸强度大于1200MPa的钨合金穿甲弹弹芯材料的主要途径。形变强化主要通过旋锻、静液挤压、热挤压或其它热机械加工复合变形技术实现。形变强化的机制主要是大变形使钨晶粒呈纤维状。本文综述了国内外对钨合金穿甲弹弹芯材料的形变强化工艺和机制的研究现状。

关键词：形变强化钨合金穿甲弹弹芯材料机制