空冷贝氏体钢破片中绝热剪切带的微观形貌特征

利用金相显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)、原子力显微镜(AFM)等设备,研究了空冷贝氏体钢爆破圆筒破片中的绝热剪切带的微观形貌特征.实验结果表明:破片中绝热剪切带为白亮带,其形貌与基体组织有明显的区别,绝热剪切带上有分叉和裂纹;衍射证明绝热剪切带内组织为晶体结构,带内有位错胞和位错缠结;原子力显微镜观测表明绝热剪切带高于基体.     

高速冲击下2519A-T87铝合金微观组织研究

用金相显微镜(OM)和透射电子显微镜(TEM)对2519A-T87铝合金靶材弹坑周围的高速冲击特征组织进行了观察分析。在OM下观察分析发现弹坑周围形成了变形带和绝热剪切带,裂纹在绝热剪切带内萌发和扩展。TEM下观察分析发现变形带内为微带组织,绝热剪切带内是动态再结晶组织。位错在微观组织演化过程中起到了重要作用。显微硬度测试结果表明,绝热剪切带的硬度值远远低于基体。     

宽带激光熔覆铸造WCp /Ni基合金复合涂层结合界面组织特征

研究了宽带激光熔覆铸造WCp /Ni基合金复合涂层结合界面组织特征。结果表明结合界面微区组织特征为细小的共晶体组织、过渡层组织以及白亮带组织。白亮带及过渡层中主要含有Fe ,Cr,Ni,Si等元素。白亮带主要是单相的γ - (Fe ,Cr ,Ni,Si)固溶体组织。从熔覆区→过渡层→白亮带的平均显微硬度值呈梯度分布。复合涂层结合界面主要元素、微观组织结构和显微硬度呈梯度分布的特征 ,提高了涂层与基材之间的匹配性 ,缓解应力集中 ,避免裂纹形成 ,实现了基材与涂层良好的冶金结合。     

切削高强度结构钢形成的绝热剪切带微结构观察

使用扫描电子显微镜和透射电子显微镜对高强度结构钢30CrNi3MoV正交切削产生的切屑内绝热剪切带的微细组织进行了观察，测量了绝热剪切带的显微硬度。绝热剪切带中心和基体组织之间，组织是渐变的。绝热剪切带内硬度达到了淬火马氏体硬度，并具有细小的等轴晶组织，内部含有少量χ-Fe6C2和Fe3C碳化物与奥氏体。基体和剪切带之间的过渡区为大塑性变形的马氏体组织，分布有高密度的位错。研究结果表明，在实验切削条件下得到的绝热剪切带属于相变带。     

宽带激光熔覆铸造ＷＣp／Ni基合金复合涂层结合界面组织特征

研究了宽带激光熔覆铸造ＷＣp/Ｎｉ基合金复合涂层结合界面组织特征。结果表明结合界面微区组织特征为细小的共晶体组织、过渡层组织以及白亮带组织。白亮带及过渡层中主要含有Fe,Cr,Ni,Si等元素。白亮带主要是单相的γ－(Fe,Cr,Ni,Si)固溶体组织。从熔覆区→过渡层→白亮带的平均显微硬度值呈梯度分布。复合涂层结合界面主要元素、微观组织结构和显微硬度呈梯度分布的特征,提高了涂层与基材之间的匹配性,缓解应力集中,避免裂纹形成,实现了基材与涂层良好的冶金结合。     

30MnCrNiMoB钢绝热剪切带的显微观察与微结构分析

３０ＭｎＣｒＮｉＭｏＢ低合金钢板（１５ｍｍ厚）经９００℃淬火．４００℃×２ｈ回火，在模拟穿甲弹射击下，背强为４３７ｍ／ｓ．弹坑周围用硝酸酒精腐蚀可观测到白亮的绝热剪切带（ＡＳＢ）．带的尖端分布着向基体发散的流变线．透射电镜观察显示带中为严重碎化的马氏体，其衍射花样几乎等于多晶环．绝热剪切带内除马氏体外尚有细小碳化物．本文证实这种绝热剪切带是一种形变带，并测得最大剪切应变为１９００％．     

二次退火时间对TNM合金微观组织和硬度的影响

研究了TNM(Ti-Al-Nb-Mo)合金中热处理条件与显微组织、力学性能的关联.将合金样品先在1 270℃下退火后,再分别于800℃保温500、1 000和2 000 h.利用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和显微硬度计分析了具有不同二次退火时间样品的物相、微观形貌及显微硬度的变化.结果表明:随着退火时间的延长,(α2+γ)层片团边界逐渐粗化,界面处出现更多的βo和γ组成的网络状组织;同时在α2层片内出现更多的纳米级βo颗粒,使单个α2层片中出现α2/βo/α2结构.由于βo颗粒的硬度较大,且层片内的α2/βo界面可以阻碍位错的运动,所以TNM合金的硬度随着二次退火时间的延长而有所提高.     

化学镀镍磷合金层的性能研究

在45钢表面获得了磷含量为10%的化学镀Ni—P合金层,研究了热处理对Ni-P合金层性能的影响.结果表明:化学镀Ni-P合金层经400℃热处理显微硬度高达1070HVO.1.经600℃热处理后硬度仍高达610HVO.1,且具有良好的耐蚀性和抗热疲劳性能.     

钛在爆炸复合冲击载荷下的绝热剪切现象

研究了在爆炸复合冲击载荷下工业纯钛和低碳钢（ＴＡ２／Ａ３）爆炸复合界面层附近ＴＡ２侧出现的绝热剪切带（ＡＳＢ）内的显微组织，表明其ＡＳＢ内具有等轴微晶组织特征并未发现微裂纹，ＡＳＢ内的显微硬度比附近基体略高，对仅在ＴＡ２侧产生ＡＳＢ，而在Ａ３侧从未观察到．这一现象从材料－力学－热学上进行了综合分析讨论．结果表明：应变丰和应变都影响绝热剪切过程；在爆炸复合冲击载荷这一近似绝热条件下，材料本身的物理性能（如比定容热容ｃｖ，密度ｐ等）、刀学性能（如导热系数ｋ）都影响ＡＳＢ产生的倾向性．     

等温处理对新型高强钢力学性能和绝热剪切行为的影响

为了使新型高强钢更好地在冲击领域得到应用,采用等温盐浴方法对新型高强度钢进行热处理.通过OM、SEM、TEM对材料的微观组织进行观察,采用万能试验机对材料进行准静态拉伸力学性能测试,通过分离式霍普金森压杆（SHPB）对材料进行动态性能测试并捕捉临界应变率下萌生发展的绝热剪切带形貌.研究结果表明:随着等温温度的升高,对应材料的主要组织由马氏体+下贝氏体,马氏体+下贝氏体+上贝氏体变化为马氏体+上贝氏体,材料的屈服强度和塑性逐渐降低.330℃等温处理的材料绝热剪切带萌生的临界应变率为3种等温处理材料中最低,上贝氏体组织的出现使材料对绝热剪切变形的敏感性降低.      

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

正~~