热变形奥氏体先共析铁素体的热力学计算

用超组元模型为热力学基础,计算了35CrMo结构钢合金形奥氏体→铁素体转变的亚稳碳摩尔分数x_C~(α/γ)和x_C~(γ/α)以及先共析铁素体析出驱动力△G~(γ→α γ′),并讨论了不同的形变温度和形变速率对亚稳碳浓度和先共析铁素体析出驱动力的影响.未变形钢的先共析铁素体热力学平衡温度A_(e3)的计算值与实测值基本符合.分析了γ相热变形对A_(e3)的影响。     

热变形温度对先共析铁素体等温转变动力学的影响

试验研究了一种Cr－Mn－Mo－B低碳低合金高强钢奥氏作热变形温度对相变前奥氏体组织状态及对先共析铁素体等温转变动力学的影响，结果表明，随着奥氏体热变形温度的降低，相变前奥氏体晶粒减小，并且先共析铁素体等温转变孕育期缩短，先共析铁素体转变量增多．     

Fe-C-X系合金针状铁素体在奥氏体贫碳区先共析转变的热力学分析

针状铁素体组织强度高、韧性好,基于氧化物夹杂形核,有很强的自身细化晶粒的能力,获得大量超细针状铁素体组织是超级钢研究的主要发展方向.建立了Fe-C-X系合金针状铁素体在奥氏体贫碳区先共析转变的热力学模型,并对Q235钢进行了数值模拟.结果表明,针状铁素体在实际相变开始温度(约923 K)的相变驱动力(绝对值)为450～740 J/mol,而且随着贫碳区碳含量的减少而增加.该模型可获得比以往扩散模型更大的相变驱动力,从热力学角度来讲,针状铁素体在奥氏体贫碳区很可能具有先共析转变的相变过程.     

Fe-C-X系合金针状铁素体在奥氏体贫碳区先共析转变的热力学分析

针状铁素体组织强度高、韧性好，基于氧化物夹杂形核，有很强的自身细化晶粒的能力，获得大量超细针状铁素体组织是超级钢研究的主要发展方向。建立了Fe—C-X系合金针状铁素体在奥氏体贫碳区先共析转变的热力学模型，并对Q235钢进行了数值模拟。结果表明，针状铁素体在实际相变开始温度（约923K）的相变驱动力（绝对值）为450-740J／mol，而且随着贫碳区碳含量的减少而增加。该模型可获得比以往扩散模型更大的相变驱动力，从热力学角度来讲，针状铁素体在奥氏体贫碳区很可能具有先共析转变的相变过程。     

形变奥氏体→铁素体转变的动力学研究

基于相变动力学和热力学原理，并根据Schieil叠加原理和热膨胀实验结果，建立了形变奥氏体(γ)→铁素体(α)连续冷却相变动力学行为的预测模型，将其应用于形变奥氏体后的控制冷却过程，可以计算出铁素体相变开始温度以及室温组织中的体积分数等参数．该方法的计算模拟结果与实测结果吻合很好，表明这种理论的计算方法是可行的．     

中碳铝硅镇静钢连铸坯的高温延塑性

采用Ｇｌｅｅｂｌｅ－１５００热模拟实验机测试了宝钢生产的易出现角模裂纹缺陷的中碳铝硅镇静钢ＧＲ４１５１连铸坯的高温延塑性，并通过金相、扫描电镜等对拉断后试样的断口及组织形貌进行了分析检验。结果表明：ＧＲ４１５１钢在熔点￣７００℃的温度区间存在２个脆性区域，即熔点￣１３３０℃的第Ｉ脆性区和８６０￣７４０℃的第Ⅲ脆性区，γ单相域ＡＩＮ等氮化物在γ晶界析出在γ＋α两相区先共析铁素体叶网状并在γ晶界析出是     

中碳亚包晶成分钢连铸坯角横裂的防止对策

宝钢生产的中碳亚包晶成分钢连铸坯角横裂属于沿晶界的开裂，主要发生在８５０℃以下温度，对３个钢种连铸坯试样的高温力学性能的测定表明，在ε＝４×１０＾－３／ｓ应变速率下，所测钢种在熔点～７００℃范围存在两个脆性温度区域，即熔点～１３５０℃的第Ｉ脆性温度区域和８５０～７２５℃的第Ⅲ脆性温度区域，在第Ⅲ脆性温度区域，γ单相域Ａ１Ｎ等氮化物在γ晶界的析出和在γ＋α两相区先共析α相呈网膜状，在γ晶界的析出是造     

亚共析合金钢40Cr铁素体和珠光体恒温转变动力学

用膨胀法和金相法研究了亚共析合金钢４０Ｃｒ铁素体和珠光体恒温转变 动力学。提出了用碳当量计算Ａ１～Ａ３温度区间亚共析合金钢铁素体恒温转 变动力学公式。测出了Ａ１温度以下的拐点温度；在拐点温度以下，铁素体和珠光体转变符合Ｊｏｈｎｓｏｎ－Ｍｅｈｌ公式。讨论了在拐点温度至Ａ１温度之间，铁 素体和珠光体恒温转变的动力学公式。     

18Mn18Cr高氮钢析出相特征及形成机制

通过金相显微镜、扫描电镜、电子探针显微分析、透射电镜及热力学计算软件研究C和N含量对铸态及时效态18Mn18Cr高氮钢析出相特征及形成机制的影响.研究发现在铸态,随C/N质量比降低,析出相依次为Cr23C6相、σ相和Cr2N相.增加C或N含量可分别促进Cr23C6相和Cr2N相析出.C和N含量影响实验钢凝固模式及不稳定铁素体相共析分解产物.18Mn18Cr0.44N钢凝固模式为AF模式,不稳定铁素体相共析分解反应为δ→σ+γ2(0.025%C)和δ→γ2+Cr23(CxNy)6(x/y>1)(0.16%C);18Mn18Cr0.72N钢凝固模式为A模式,晶界处存在少量颗粒状Cr2N相.在固溶时效态,实验钢仅析出片层状的Cr2N0.39C0.61相.随C+N含量增加,片层状析出相体积分数和片层间隙增加,析出孕育时间减少.     

Q235碳素钢不同热变形条件下退火过程的织构分析

利用扫描电镜、背散射电子衍射(EBXD)和X射线衍射技术研究了三种方式热变形后保温时铁素体的长大行为.结果表明,回复、再结晶和长大的相对程度与第二相粒子的状态及铁素体的取向分布有关.形变强化相变产生的超细铁素体中形变储存能较低,退火时难以发生静态再结晶,而以晶粒长大为主,铁素体因第二相出现较晚而充分生长:A1温度以下纯铁素体区形变的铁素体虽然形变储存能最高,形变量最大,但第二相钉扎最明显,铁素体仅发生部分再结晶,<111>取向形变晶粒比<100>取向形变晶粒更明显地被削弱;α+γ两相区形变时,铁素体(亚)晶粒发生回复式长大,<111>取向晶粒和<100>取向晶粒有不同的再结晶倾向.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

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