Nb对快淬Nd10Fe84B6合金微观组织和磁性能的影响

研究了添加Nb对快淬Nd10Fe84B6合金磁性能、微观组织和晶化温度的影响.结果表明:添加Nb可以提高快淬态合金中非晶相的热稳定性,减小最佳退火温度和晶化起始温度之间的温度差,抑制热处理时α-Fe和Nd2Fe14B晶粒的预先析出和长大,有效细化了晶粒,提高磁性能.快淬Nd10Fe83Nb1B6合金经过715℃热处理10 min,磁性能达到Br=0.90 T,iHc=750 kA/m,(BH)max=120 kJ/m3,较之Nd10Fe84B6合金,内禀矫顽力提高了25%,最大磁能积提高了14%.     

超快冷对含Nb钢相变行为的影响

为揭示超快冷对含Nb钢相变行为的影响机制,利用MMS-300热/力模拟试验机研究超快冷+层流冷却条件下含Nb钢的相变行为。研究结果表明:实验钢于680℃处于铁素体相变区;当冷却速度大于20℃/s时,实验钢于600℃处于针状铁素体和贝氏体相变区。实验钢变形后冷却至铁素体相区后,随着保温时间的延长,铁素体含量逐渐增加;当保温时间超过76.5 s时,超快冷工艺下的铁素体含量高于层流冷却工艺下的铁素体含量。当前段冷却速度达到30℃/s时,组织中出现硬相组织,继续增大冷却速度,对最终相变组织影响不大。     

影响２０MnSi棒材质量原因分析

针对济钢２０MnSi棒材曾出现断裂现象,从微观组织、化学成分、出钢湿度以及终钢温度等方面进行了探讨。认为钢坯中元素含量与均匀程度是影响棒材质量的重要因素,并提出２０MnSi钢中,Ｃ含量最好控制在0.18-0.24%,Mn含量控制在１.2%-1.6%,Mn/Si比值控制在３.0左右,Ｓ含量控制在０.025%以上;加热炉温度可控制在ＡＣ３线以上３０－５０℃,固相线ＮＳＥ以上１００－１５０℃之间;加热时间宜控制在８０－１００min;终轧温度在ＡＣ３线以上５０－１００℃。     

添加硼对La-Mg-Ni系(PuNi3-型)贮氢合金微观结构及电化学性能的影响

为了提出La-Mg-Ni(PuNi3型)系贮氢合金的电化学循环稳定性,在La2Mg(Ni0.85Co0.15)9合金中添加微量的B,用铸造及快淬工艺制备La2Mg(Ni0.85Co0.15)9Bx(x=0,0.05,0.10,0.15,0.20)贮氢合金,分析测试铸态及快淬态合金的微观结构与电化学性能,研究硼对合金微观结构及电化学性能的影响。结果表明:铸态合金具有多相结构,包括主相(La,Mg)Ni3相(PuNi3型)和LaNi5相,一定量的LaNi2相和微量的Ni2B相经快淬处理后,Ni2B相消失,且其他相的相对量随淬速的变化而变化。硼的加入提高了铸态及快淬态合金的循环稳定性,但使铸态合金的容量下降;铸态合金的电化学容量随B含量的增加单调下降,而快淬态合金的容量随B含量的增加有一极大值,B对铸态及快淬态合金电化学性能的影响机理是完全不同的。     

Nd_2Fe_(14)C/α-Fe系稀土永磁材料微观组织及磁性能

为了提高纳米双相稀土永磁材料Nd2Fe14B/α-Fe的性能,研究了一种新型合金Nd9.0Fe85.5Nb1.0B4.0C0.5。在合金中添加碳可提高矫顽力,添加钕可细化晶粒;合金的淬态微观组织显著影响其磁性能,合金中的部分预析出微晶相有助于在随后的热处理中获得均匀的微观组织;在热处理工艺中,晶化退火温度和时间对合金微观组织结构具有显著影响,并影响合金的磁性能。使用原子力/磁力显微镜观察Nd-Fe-(BC)/α-Fe纳米复合磁体的微观组织及磁畴结构,并由此对纳米双相稀土永磁材料中的交换耦合作用进行了解释。结果表明,最佳热处理工艺为:700℃保温15min,其性能为:剩磁1.381Wb.m-2,矫顽力518.05kA.m-1,剩磁比0.74,最大磁能积137.75kJ.m-3。     

Nd2Fe14(BC)/α-Fe系稀土永磁材料微观组织及磁性能

为了提高纳米双相稀土永磁材料Nd2Fe14B/α-Fe的性能,研究了一种新型合金Nd9.0Fe85.5Nb1.0B4.0C0.5. 在合金中添加碳可提高矫顽力,添加钕可细化晶粒; 合金的淬态微观组织显著影响其磁性能,合金中的部分预析出微晶相有助于在随后的热处理中获得均匀的微观组织; 在热处理工艺中,晶化退火温度和时间对合金微观组织结构具有显著影响,并影响合金的磁性能.使用原子力/磁力显微镜观察Nd-Fe-(BC)/α-Fe纳米复合磁体的微观组织及磁畴结构,并由此对纳米双相稀土永磁材料中的交换耦合作用进行了解释.结果表明,最佳热处理工艺为 700 ℃保温15 min, 其性能为 剩磁1.381 Wb*m-2, 矫顽力518.05 kA*m-1, 剩磁比0.74, 最大磁能积137.75 kJ*m-3.     

分段冷却模式下热轧双相钢的组织演变及力学性能

通过热模拟实验研究了分段冷却模式下变形温度、保温温度及保温时间对Nb-Ti微合金热轧双相钢组织演变及性能的影响.结果表明:降低变形温度可促进铁素体的转变,使马氏体形态由大块状过渡到岛状;保温温度从740℃逐渐降至580℃时,铁素体转变量先增加后减少,保温温度为660℃时铁素体转变量达到峰值;随保温时间延长铁素体转变量增加,且铁素体转变量与时间的关系曲线呈“S”型.采用超快冷+空冷+层流冷的冷却模式并通过调整终轧温度及空冷时间获得了630~710MPa的热轧双相钢,屈强比≤061,相应的组织为铁素体+马氏体或铁素体+马氏体+少量的贝氏体.     

热处理对Al-W合金组织及性能的影响

选取W含量为7%的Al-W合金为研究对象,研究了固溶和时效对合金微观组织、硬度及耐磨性的影响。研究结果表明:固溶温度、固溶时间、时效温度和时效时间对合金的组织和性能有较大影响。对于含W为7%的Al-W合金,随着固溶温度的升高,合金的耐磨性和硬度增强;随着时效温度的升高和时效时间的延长,合金的硬度增大、耐磨性增强。实验条件下,合金最佳热处理工艺为530℃固溶80 min,220℃时效10 h。     

20MnSi钢筋冷却的淬透层深度

通过数值方法求解20MnSi钢筋在线冷却过程中的温度场，进而求得组织场，并分析了各控冷工艺参数对20MnSi钢筋在线冷却过程中的淬透层深度的影响．结果表明：组织场的实验结果与计算结果符合较好，可以通过调整控冷工艺参数控制淬透层深度，为得到高强钢筋需要增大冷却水量，降低冷却水温；钢筋端面单元剖分的粗细会影响计算结果，使淬透层深度与控冷工艺参数之间呈阶跃式变化．     

快淬Mg2Ni型合金的结构及贮氢动力学

用快淬技术制备Mg2-xLaxNi(x=0,0.2,0.4,0.6)贮氢合金,用XRD,SEM和HRTEM分析合金的微观组织结构;测试合金的气态及电化学贮氢动力学。结果表明:快淬二元Mg2Ni合金具有典型的纳米晶结构,而快淬La替代合金明显地具有非晶结构,La替代Mg提高Mg2Ni型合金的非晶形成能力。La替代Mg明显地改变Mg2Ni型合金的相组成,当x=0.4时,合金的主相改变为(La,Mg)Ni3+LaMg3。快淬及La替代明显影响合金的气态及电化学贮氢动力学,La替代使合金的吸氢动力学先降低后增加,但使合金的气态脱氢及电化学贮氢动力学先增加后降低。快淬对合金气态及电化学贮氢动力学的影响与合金的成分相关,对于La0.4合金,合金的气态吸氢动力学随淬速的增加先增加后减小,其放氢动力学随淬速的增加而增加。     

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