高能球磨对TiC0.5/Cu(Al)复合材料组织和性能的影响

以Ti2AlC和Cu粉作为原料,分别采用滚筒球磨和高能球磨对原料粉进行预混处理,在1 150℃下原位热压反应制备了TiC0.5/Cu(Al)复合材料.实验结果表明,Al从Ti2AlC溶出进入Cu中,Ti2AlC分解并转变成TiC0.5相,然而滚筒球磨制备的复合材料中生成少量AlCu2Ti相.通过对原料粉高能球磨处理,制备后的复合材料AlCu2Ti相消失,细小的TiC0.5颗粒均匀分布于基体中.两种不同方法制备的复合材料的弯曲强度和维氏硬度试验结果表明,高能球磨工艺能提高TiC0.5/Cu(Al)复合材料的弯曲强度,同时维氏硬度略有降低.其中,高能球磨处理后制备的27％ TiC0.5/Cu(Al)复合材料的弯曲强度达到981 MPa,维氏硬度为2.43 GPa.     

磁控溅射沉积Cu-W薄膜的结构及性能

 以磁控溅射制备W原子数分数为2.1%~53.1%的Cu-W薄膜,用EDX、XRD、TEM、SEM、显微硬度计和四探针电阻仪对薄膜成分、结构和性能进行表征,研究薄膜中W含量的变化对薄膜结构及性能的影响.结果表明,Cu-W薄膜呈纳米晶结构,含x=2.1%~16.2%W的Cu-W膜中存在W在Cu中的铜基fcc Cu(W) 非平衡亚稳过饱和固溶体,Cu-36.0%W膜中存在fcc铜基和bcc钨基双相固溶体,含x=48.7%~53.1%W的Cu-W膜则存在Cu在W中的钨基bcc W(Cu)亚稳过饱和固溶体.具两相结构的Cu-36%W薄膜的显微硬度最大,而Cu-W膜电导率则随W含量上升而持续降低.400 ℃退火1 h后,Cu-W薄膜发生基体相晶粒长大,硬度降低,但电导率提高.Cu-W薄膜在退火后结构和性能变化的主要原因是退火中基体相晶粒发生了长大.     

热处理对激光立体成形Ti_3Al/TC11连接界面组织性能的影响

通过对激光立体成形Ti3Al/TC11连接界面沉积态、去应力退火和固溶时效3种状态的组织进行对比研究,探索改善Ti3Al/TC11连接界面组织以提高其性能的新途径。研究表明,沉积态试样在两个基体与过渡区交界处组织形貌差异较大,经去应力退火后试样连接界面的组织形貌与沉积态相比变化不大,但针状α′相长度明显减小,Ti3Al侧β晶界厚度减小且变模糊。经固溶时效处理后,两个基体与过渡区交界处组织形貌差异较小,均为等轴、细小α相、α2相和转变β相的三重混合组织,β晶界消失,沿整个试样显微硬度值分布均匀,相比去应力退火态其显微硬度整体较高,这可能与弥散相的固溶强化作用有关。     

热处理对激光立体成形Ti3Al/TC11连接界面组织性能的影响简

通过对激光立体成形Ti3 Al/TC11连接界面沉积态、去应力退火和固溶时效3种状态的组织进行对比研究,探索改善Ti3 Al/TC11连接界面组织以提高其性能的新途径。研究表明,沉积态试样在两个基体与过渡区交界处组织形貌差异较大,经去应力退火后试样连接界面的组织形貌与沉积态相比变化不大,但针状α′相长度明显减小,Ti3 Al侧β晶界厚度减小且变模糊。经固溶时效处理后,两个基体与过渡区交界处组织形貌差异较小,均为等轴、细小α相、α2相和转变β相的三重混合组织,β晶界消失,沿整个试样显微硬度值分布均匀,相比去应力退火态其显微硬度整体较高,这可能与弥散相的固溶强化作用有关。     

退火处理对过饱和Cu-Mo合金膜微观结构的影响

采用磁控溅射方法在柔性聚酰亚胺(PI)基体上沉积了Cu-Mo合金薄膜,对样品进行了真空退火处理。利用X射线、场发射扫描电镜、能谱仪表征了退火前后合金膜及纯Cu膜的成分、物相结构、表面形貌,分析了退火处理对合金膜微观结构的影响以及退火后合金膜表面Cu颗粒的形成机理。研究结果表明:退火处理后合金膜微观结构发生了明显变化。退火后Cu-21.3%Mo合金膜表面自形成了大量多面体Cu颗粒,颗粒尺寸为几十纳米到数百纳米,并且随着退火温度逐渐升高,薄膜表面自形成颗粒数量逐渐增加。     

放电等离子烧结制备Cu/Ti3SiC2-TiC复合材料

选用单质粉(Ti,Si,C,Al)为原料,采用机械合金化法制备含有Ti3SiC2和TiC的混合粉体,然后将Ti3SiC2,TiC和Cu的混合粉体进行放电等离子烧结,以制备Cu/Ti3SiC2-TiC复合材料,并对其组织耐磨性进行了研究。实验结果表明,放电等离子烧结可制备致密的Cu/Ti3SiC2-TiC复合材料,复合材料的显微硬度随强化相(Ti3SiC2-TiC)掺加量的增加显著提高,当强化相掺加量为20 vol%时,复合材料的硬度值达1.58 GPa。Cu/Ti3SiC2-TiC复合材料的耐磨性随强化相含量增加显著提高,当强化相掺入量为20 vol%时,复合材料的耐磨性为纯Cu的4倍。     

Al含量对TiAlN涂层热稳定性能的影响

采用阴极电弧蒸镀在WC-Co硬质合金基体上沉积Ti1-xAlxN涂层(x=0.5、0.55和0.6),并对涂层试样在900℃下真空退火0.5～4 h.采用X线衍射仪(XRD)和显微维氏硬度计分析比较退火前后TiAlN涂层物相及硬度,研究Al含量对涂层结构、硬度和热稳定性能的影响.研究结果表明:Ti0.5Al0.5N和Ti0.45Al0.55N为单相面心立方结构,Ti0.4Al0.6N为面心立方(fcc)TiAlN和密排六方(hcp)AlN双相结构.涂层退火时发生分解,先析出介稳相fcc-AlN,再转变为稳定相hcp-AlN和fcc-TiN,硬度逐渐下降.Ti0.45Al0.55N涂层高温下能保持较长时间的稳定,退火后仍具有最高的硬度,表现出优异的热稳定性;而Ti0.4Al0.6N涂层中因存在hcp-AlN硬度略低,分解最早,热稳定性最差.当x=0.55时为最佳涂层成分.     

粉末冶金制备Ti-Cu二元合金和力学性能的研究

以纯钛(Ti)粉和铜(Cu)粉为原料,采用粉末冶金法,真空烧结制备Ti-Cu(质量分数)二元合金。利用X射线衍射(XRD)、扫描电镜(SEM)、能谱仪(EDS)等测试手段对样品的相组成、成分、微观组织形貌等进行表征,用硬度仪测试材料的宏观及微观硬度。研究结果表明:Ti、Cu粉末在850-1200℃真空烧结后,合金中存在αTi、CuTi_2、CuTi_3三相;随Cu含量的增加,Ti-Cu合金的相对密度及硬度都是先升高后降低,当含铜量为5%的合金相对密度达到89.2%,洛氏硬度达到49HRA,合金的致密度较好;Ti-Cu共析相的显微硬度为370HV,随着CuTi_2、CuTi_3相的析出,合金硬度下降。     

Ti与Al比例及退火温度对AlGaN/GaN HEMT欧姆接触影响

利用热蒸发方法制备了Ti/Al金属双层结构的AlGaN/GaN高电子迁移率晶体管(HEMT)欧姆接触,Ti与Al比例分别为1∶2(20 nm/40 nm)、1∶5(20 nm/100 nm)和1∶8(20 nm/160 nm).采用相同退火时间、不同退火温度对不同的Ti与Al比的AlGaN/GaN HEMT结构进行退火.通过XRD对电极结构进行了分析,利用金相显微镜观察了电极的表面形貌.实验结果显示,相同退火时间条件下,退火温度在800℃, Ti与Al比为1∶5的AlGaN/GaN HEMT结构形成了较好的欧姆接触.     

Cu/Ti3 AIC2复合材料的耐磨性研究

以元素单质粉Ti,Al,C,Cu为原料,采用机械合金化和放电等离子烧结(SPS),成功制备了Cu/Ti3AlC2复合材料块体,并对其进行了组织性能分析.实验结果表明:采用SPS烧结技术制备的Cu/Ti3AIC2复合材料,随着Ti3AIC2含量的增加,其显微硬度逐渐提高,相同烧结工艺条件下(900℃烧结,保温20 rain)添加15vol%Ti3AlC2复合材料的硬度比纯Cu提高近2倍;添加适量的Ti3AlC2可显著提高复合材料的耐磨性,当复合材料中含5vol%Ti3AlC2时,磨损量降低30%以上.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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