不同变形方式对5083铝合金组织的影响

为了获得较细的晶粒,采用等通道角挤压(ECAP)变形的方法对5083铝合金按A和B两种方式进行变形;变形后两种样品用背散射电子衍射(EBSD)技术进行测定,获得了极图、反极图、取向差分布、晶粒尺寸等实验结果.结果表明:5083铝合金按A方式晶粒细化效果强于B方式,而B方式织构面积及织构强度都大于A路径.     

采用ECAP制备亚微晶铝合金及其力学性能

采用ECAP与热处理工艺相结合制备了亚微晶7050和2224铝合金,并研究了力学性能·结果发现,ECAP后进行固溶和时效处理,晶粒细化到06μm;力学性能明显提高,7050合金的抗拉强度σb为616MPa,延伸率δ为17%,2224合金的抗拉强度σb为618MPa,延伸率δ为12%,成为亚微晶超高强铝合金     

等径弯曲通道变形制备超细晶铝合金的组织性能

用等径弯曲通道变形(ECAP)的方法制备出超细晶铝合金材料,并研究了在不同道次条件下其显微组织的演化过程.研究表明,随着强烈塑性变形的增加,显微组织中开始形成大量晶粒尺寸小于1μm的位错胞组织,当其晶界取向差增大时,亚晶粒变为越来越细的板条状组织.当经过8道次ECAP变形后,晶粒尺寸由变形前的约50μm细化为约0.2μm.该超细晶铝合金材料在150℃的退火条件下,其晶粒尺寸稳定在0.2～0.3μm的范围内.在温度为500℃、应变速率为10-3s-1的拉伸实验中,该超细晶铝合金材料的最大延伸率高达370%,呈现出良好的超塑性.     

退火温度对20MnSi钢ECAP变形组织的影响

采用C方式等径弯曲通道变形(ECAP)法制备了平均晶粒尺寸～0.20 μm的亚微晶20MnSi钢,研究了退火温度对ECAP变形组织的影响.结果表明,随退火温度升高,ECAP变形获得的亚微晶铁素体变形组织在原位逐渐演变为再结晶组织,300～500℃退火1 h后,亚微晶铁素体组织稳定,晶粒无明显长大.退火温度高于500℃后,铁素体晶粒开始明显长大,650℃退火后的铁素体平均晶粒尺寸～8μm.经ECAP变形的珠光体组织在较低温度退火时,渗碳体具有较强的球化能力.     

Al-Mg系铝合金超塑性薄壁管材

采用熔铸—均匀化退火—挤压工艺研制Al-5.60Mg-0.30Zr-0.07Cr-0.16Mn（质量分数,%）合金管材。对该合金管材进行析出退火处理后,采用热旋—退火—冷旋工艺制备薄壁旋压管。采用金相显微镜、扫描电镜、拉伸性能测试等手段研究该铝合金旋压管冷变形态与完全再结晶退火态的组织与性能,测试其超塑性能,讨论其超塑性变形与断裂行为。研究结果表明,在Al-Mg铝合金中加入微量锆、铬、锰,可以促使试验合金中第二相颗粒弥散分布,减小后续加工的变形不均匀性;Al-5.6Mg-0.30Zr合金经析出退火—旋压变形后,于500℃退火1 h的再结晶退火组织晶粒平均粒径小于10μm。     

等通道转角挤压-扭转的纯铜变形行为模拟

采用DEFORM-3D有限元模拟软件对纯铜等通道转角挤压-扭转(ECAP-T)进行模拟研究,研究变形过程中试样的等效应力和等效应变分布及变形路径对等效应变分布的影响,对变形后晶粒的细化效果进行分析.结果表明:相对于单纯ECAP变形,ECAP-T具有更大的应变量和更好的晶粒细化效果;多道次挤压后试样沿Bc路径的等效应变分布最均匀,沿A路径较差;ECAP等效应变主要集中在试样的中心部位,但ECAP-T等效应变主要集中在试样表面;ECAP-T变形后沿Bc路径的晶粒细化均匀性最好,Ba路径次之,A路径最差,且变形后试样纵截面上外侧点的变形均匀性比中心处好.     

基于MATLAB统计工具箱的5182铝合金组织及性能研究

文章比较不同细化方法细化5182铝合金的晶粒细化能力,同时用MATLAB统计工具箱采用统计分析方法对均匀化处理前后的5182铝合金的硬度进行分析.结果证明,Al-5Ti-1B细化合金的晶粒最小,含钛铝锭(GRAI) 0.25%Zr细化合金的晶粒略大于Al-5Ti-IB细化合金;GRAI中分别加入0.16%La、0.20%RE(富铈混合稀土)后,合金晶粒变化不大;GRAI制造的5182铝合金比Al-5Ti-IB、Al-10Ti中间合金细化的合金硬度高;加0.25%Zr使GRAI制造合金硬度增加;对于均匀化前的合金,加0.16%La使GRAI制造合金硬度减小,而加0.20%RE硬度变化较小;对于均匀化处理后的合金,加0.16%La使GRAI制造合金硬度变化较小,而加0.20%RE使GRAI制造合金硬度增加.均匀化处理,使合金的硬度有所下降,GRAI 0.25%Zr细化合金的硬度下降幅度最大.     

ZLD11铝合金晶粒细化分析

以ZLD11铝合金为研究对象,通过添加Sr来改变ZLD11铝合金的晶粒度,以达到细化晶粒的目的.介绍了ZLD11铝合金中元素的性质及作用,ZLD11铝合金的熔炼方法.以AlSr合金的形式加入熔体中,按照Sr的加入量占成品合金的0.04%,0.06%,0.08%以及0.10%来改变ZLD11铝合金的晶粒度,通过观察金相照片和测定晶粒度,来寻求合理的Sr的加入量,结果表明:采用X金属模铸造和用AlSr作为变质剂可以使ZLD11的晶粒细化,当Sr的加入量为0.08%时,细化晶粒效果最好.     

扭转变形及退火处理对MP35N高温合金力学性能及微观结构的影响

采用扭转变形和退火处理调控MP35N合金的微观结构并改善其力学性能,对其力学行为进行微观机理分析。研究结果表明：扭转变形在合金径向上引入了梯度位错密度,使应变最大的表面处晶粒细化并引入大量层错。梯度结构的引入使得扭转变形后合金的强度显著提高至约767 MPa,同时拥有可观的均匀伸长率(约40%);进一步的退火处理并未改变扭转变形引入的梯度结构(包括梯度位错密度和晶粒尺寸),但退火处理导致合金中一部分位错的湮灭,并使得表面区域的层错转变为纳米孪晶。退火处理导致纳米孪晶的形成以及“铃木(Suzuki)效应”的作用使得合金发生了二次硬化。退火过程产生的二次硬化与位错湮灭导致的退火软化相抵消,二次硬化提供的强度约为76 MPa。     

等通道转角挤压超细化合金组织性能的研究

等通道转角挤压技术是目前制备超细晶粒金属块材的最新研究领域之一.本实验采用了等通道转角挤压技术对3种商业铝合金以A、B、C等3种方式挤压,结果表明:3种挤压方式后的硬度与挤压道次的关系基本一致,即3~4次挤压后硬度趋于饱和;应用的负荷大小对ECAP期间剥落的可能性也被测量,以便改善挤压过程.X-射线衍射分析法显示挤压后这些铝合金出现亚微米级晶粒尺寸.本实验中,经不同方式等通道转角挤压(ECAP)铝合金组织结构变化有较大不同,晶粒得到明显细化.     

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