Ti注入钢时金属间化合物形成对钢强化机理的研究

探讨了 Ti 注入 H13钢时形成 Ti 和 Fe 合金相的规律以及 Ti 注入钢的硬化机理.根据辐射损伤理论给出了离子注入引起的空位和间隙原子产生率微分方程,并导出了平衡态时方程的解.研究了注量、能量和靶温对合金形成的影响.注入后退火的样品表面硬度可提高40～50%.用 X衍射和透射电子显微镜测量了 Fe_2Ti 和 FeTi 合金相.用维氏硬度计测量了上述诸条件下注入样品的表面硬度,用针盘磨损机测量了样品抗磨损特性.分析了这些合金相对表面硬化和抗磨损影响的机制.     

金属离子注入纳米结构和特性

材料中纳米弥散相的形成对材料强化有着非常重要的作用,离子注入技术在材料表面容易形成这种结构.透射电子显微镜观察表明,经过Ti注入的钢,表面形成了直径为10～30nm丝状的FeTi和FeTi2相,其长度为150～320nm, 当束流密度分别为25～50μA*cm-2时,弥散相的密度分别为1.2×1011和6.5×1010 cm-2,其平均直径则分别为10和18nm. 扫描电子显微镜观察C+Ti样品表明, 注入后表面形成的抗腐蚀钝化层也为丝状纳米结构, 细丝直径25～60nm,长度100～200nm,密度约2.2×109 cm-2.这种致密的结构具有很强的抗磨损特性和抗腐蚀特性.抗磨损特性提高了8倍.电化学测量结果表明,随注量的增加,腐蚀电流密度Jp明显下降,用3×1017 cm-2注量的Ti注入H13钢Jp比未经注入之值降低到0.125%～0.050%; W注入聚脂膜(PET)形成了10～20nm W的析出相,这种相的析出使PET表面硬度增加,抗磨损和抗腐蚀特性增强,并使之形成了优良的导电层.     

钒和碳双注入钢的纳米结构、强化机制和抗磨损特性

研究了V C双重离子注入合成纳米结构、相变和抗磨损机制．研究表明，注入后可改变钢的成分，V与Fe原子比最高可达到28％；形成了纳米相弥散强化结构和无序相强化结构．从而提高了钢表面硬度，表面硬度可提高23％～146％；抗磨损也有着明显的提高，磨损阻抗为未注入钢的2．2～3．6倍．     

碳、钨离子共注入H13钢表面改性的研究

将不同单质机械混合,在不增加注入机离子源数目的基础上实现了不同离子的共注入.发现C+W离子共注入使H13钢表面强化,硬度和抗磨损能力提高,且注量的增大加强了这种强化效果.共注入增强了H13钢的抗均匀腐蚀能力,且比双注入效果好.在开始的15个周期致钝电流密度保持为零.C+W离子共注入提高了H13钢点蚀电位,大注量(4×1017 cm-2)注入时,点蚀电位升高了200mV,而双注入则使点蚀电位有所降低.     

双注入匹配的计算机模拟和Ti^＋＋N^＋双注入的实验结果

为在金属中形成所需要的合金或金属间化合物而采用双重离子注入技术.2种注入离子注入能量和注量需要合理匹配.还考虑了溅射效应和扩散效应存在时的各种修正.在计算机模拟的基础上,对 Ti~++N~+双注入 H13钢中 Fe_2Ti,TiN 和 Fe_2N 等化合物进行了测量.这些合金相和金属间化合物的形成提高了钢表面抗磨损特性.还讨论了双注入金属表面的硬化机理.     

MEVVA源强流Ti离子注入纯铜表面层的结构与性能研究

采用金属蒸气真空弧(MEVVA)离子源技术对强流Ti离子束注入到纯铜表面的结构和性能进行了系统的研究.材料表面层的机械性能测试表明:强流Ti离子注入纯铜后材料表面的硬度和耐磨性均有提高,相对于纯铜基体,5×1017 cm-2注量注入可以使材料表面硬度提高2.3倍,使表面摩擦因数下降14%.注入层的X射线结构分析表明:金属离子注入后,在纯铜表面注入层中析出了合金相,合金相的析出是材料的表面硬度和耐磨性提高的主要因素.     

Mo离子注入钢退火过程中的相变研究

着重研究了金属离子注入合成表面优化复合层的机理和纳米相镶嵌结构形成,探索了注入和退火过程中纳米结构和相变过程,讨论相变机制.实验中发现用较低束流密度的Mo离子注入钢明显地改变了钢表面的结构,可使钢表面晶粒细化,使阻止位错移动的晶界数量增多;可在钢表面形成Mo原子超饱和固溶体;随所用的束流密度的增加,注入时表面温度升高,注入的Mo原子将与钢中的铁原子和碳原子化合而形成纳米尺寸的析出相.这些弥散的析出相在钢表面形成了弥散强化.用低束流密度注入后经过退火,在钢表面也形成了纳米尺寸的析出相,从而增加了表面弥散强化的效果.随退火温度的增高,纳米析出相将会聚成大一些的纳米颗粒,颗粒之间互相连接而形成网状结构,这将会进一步增加表面强化效果.     

Al/Ti对磁控溅射TiAlN膜层结构、硬度和摩擦性能的影响

采用磁控溅射技术在炮钢基材表面制备不同Ti靶电流的TiAlN膜层。利用激光共聚焦、X射线衍射仪、扫描电镜、纳米压痕仪、多功能材料表面性能测试仪、蔡司显微镜等检测方法,研究不同Al/Ti对TiAlN膜层的粗糙度,相结构、纳米硬度、摩擦性能的影响。结果表明:磁控溅射沉积TiAlN膜层光滑致密,无大液滴,以TiN(200)、(220)为主相择优生长。Al/Ti比值为1.32时,薄膜硬度处于峰值区,纳米硬度最高可达19GPa。Al/Ti比值为0.87时硬度略微降低,但表面粗糙度最小为0.029μm,摩擦系数保持稳定最低为0.4723左右。Al/Ti比值为0.87时,表现出较好的抗磨损性能。     

Y,Y＋C和Y＋Cr注入H13钢表面改性研究

用ＭＥＶＶＡ源引出的强束流Ｙ，Ｃｒ，Ｃ注入Ｈ１３钢改善了注入层抗氧化、耐腐蚀和抗磨损特性，探索了表面改性的机理。实验结果表明单注入和Ｙ＋Ｃ，Ｙ＋Ｃｒ双注入均能得到表面改性的良好效果，双注入效果略好。表面改性的原因是注入样品氧化前后的结构和合金相发生了明显的变化。上述特性的改善和注入层结构变化、钇铁化物析出相的生成以及铁钇氧化物形成密切相关。这些氧化物经短时氧化（１０ｍｉｎ）即可形成。由于这些氧化物     

Ti离子注入聚合物纳米结构分析

采用MEVVA源引出的Ti等离子注入聚酯 (PET)薄膜 ,注量在 1× 10 172× 10 17cm- 2 范围 .用透射电子显微镜分析了金属离子注入PET纳米结构随注量增加的变化 .结果表明 ,注入的Ti原子在PET中形成了密集的纳米相 ,这些纳米相均匀地弥散分布在注入层中 .用透射电子显微镜 (TEM )观察横截面表明 ,注入层为 3层结构 .可见Ti的注入已经在注入层中形成了金属化表面 .表面硬度、抗磨损特性和电导率明显地增加 .最后分析了金属离子注入对聚合物特性的改善机理 .     

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     

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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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has