热处理对NiAlMn高温形状记忆合金相变行为的影响

研究了热处理和热循环Ni－Al－30Mn高温形状记忆合金相变行为的影响。结果表明：（1）在600－1100℃固溶淬火时，随固溶温度升高，该合金的马氏体相变温度升高；在1000℃固溶淬火后，马氏体相变开始温度和马氏体逆相变结束温度为分别为465℃和549℃，（2）在1000℃固溶处理处理和400℃时效处理后，该合金可获得良好的相变特性；热循环使相变行为的稳定性提高。（3）该合金的淬火组织由马氏体和γ相组成，其中马氏体的体积约占60％，马氏体的硬度高于γ相，时效处理后合金的相组成未变，硬度有所增加。     

多晶镍钛形状记忆合金相变伪弹性特性的研究

利用四光束云纹干涉法对多晶镍钛形状记忆合金拉伸过程中的马氏体与奥氏体相互相转变以及相界面传播的现象进行了研究.从云纹图可看到,形状记忆合金发生相变时,奥氏体与马氏体的分布以及两相的界面附近的位移场分布.利用材料试验机(MTS Sintech 10/D)获得多晶镍钛形状记忆合金的应力-应变特性;通过云纹图能够发现多晶镍钛形状记忆合金拉伸过程中马氏体的发生、生长和传播规律.结果表明,云纹干涉法可以用来研究形状记忆合金的相变,且结果直观、可靠。     

Ti-50Ni激冷合金薄带的组织、相变和形状记忆行为

用熔体激冷法制备了Ti-50Ni合金薄带,用扫描电子显微镜、透射电子显微镜、X射线衍射仪、示差扫描量热仪和弯曲试验研究了Ti-50Ni激冷合金薄带的显微组织、相组成、相变和形状记忆行为。结果表明,铸态和退火态Ti-50Ni激冷合金薄带都具有良好的形状记忆效应,其显微组织呈树枝状,由马氏体和母相组成,冷却时都发生A→R→M二阶段相变,加热时铸态和400~500℃退火态激冷合金薄带发生M→R→A二阶段相变,550~600℃退火态则发生M→A一阶段相变。随退火温度升高,马氏体逆相变温度T_A、R正相变温度T_R、R逆相变温度T_(Rr)和马氏体相变热滞△T_M升高,马氏体正相变温度T_M和R相变热滞△T_R降低。     

Au-Cu-Al合金中的马氏体转变

采用3种热处理工艺研究了Au-Cu-Al合金母相的有序化程度,分析了其A2→B2→L21的有序化转变对马氏体转变的影响,即其相变点、马氏体和母相的结构,以及400℃时效炉冷处理后没有生成马氏体的原因.结果表明,采用100℃时效1.5 h后淬火到冰水中(热处理工艺II)的热处理工艺,可以得到表面浮突的马氏体;采用从650℃直接淬火到液氮中(热处理工艺I)的热处理工艺,也会发生马氏体转变,且其均为bct结构,时效处理可使母相得到充分有序化,从而提高其马氏体转变点温度,并使马氏体转变更加充分;此外,采用400℃时效、炉冷处理并淬火(热处理工艺III)的热处理工艺,可以获得更高的母相有序度,且不会导致马氏体相变,其所产生的bct结构的新相可能是通过形核长大转变而来.     

18Ni马氏体时效钢内耗的研究

用倒扭摆法测试了18 Ni马氏体时效钢的低频内耗.发现在降温中于165℃附近出现正马氏体相变内耗峯.在升温中于700℃附近出现反马氏体相变内耗峯.内耗峯的高度与T/f(T—温度变化速率,f—振动频率)成线性关系,恒温测量时,相变内耗降为背景值.还观察到相变过程中,切变模量发生软化.我们认为这个内耗是由外加切应力促进或加速接近临界的马氏体胚芽的界面位错滑移所引起.     

形变过程中TRIP效应的相变热动态研究

采用拉伸与测温试验同时进行的方法,将应力应变曲线与热能曲线相结合,动态研究热轧TRIP钢拉伸过程中的相变热.研究表明:热轧TRIP钢在拉伸过程中材料增加的热能由部分转变的塑性功和马氏体相变热组成,因此,拉伸过程中实际测得的试样热能高于由塑性功转变的热能.利用平均综合热能损失系数对低速拉伸的TRIP钢的热能进行补充,通过计算与推导,证实了试样在刚进入塑性变形时,一定数量的较不稳定残余奥氏体首先集中发生马氏体相变,随着应变的进一步加大,剩余的较稳定的残余奥氏体根据其稳定情况发生马氏体相变的数量逐渐减少,在试样均匀延伸结束前绝大部分残余奥氏体已转变为马氏体.结合相变热变化可动态描述热轧TRIP钢形变过程中马氏体相变的情况.     

Fe对Ni-Mn-Ga形状记忆合金相变和力学性能的影响

研究了Fe含量对Ni56Mn25 xFexGa19(x=0～10)合金的微观组织结构、相变行为、力学性能和记忆特性的影响规律.当x 4时,Ni56Mn25–xFexGa19合金仍然保持着单一的四方结构马氏体相;当x 6时,合金呈现为马氏体相和面心立方γ相组成的双相结构.相对于马氏体相,γ相为富Ni和富Fe相,其含量随Fe含量的增加而增加.随着Fe含量增加,合金的马氏体相变温度逐渐降低,其峰值温度从x=0时的356℃降低至x=10时的170℃,这主要归因于马氏体相尺寸因素和电子浓度的综合作用.通过添加Fe替代Mn在合金中引入的γ相可提高合金的强度和塑性,但最大形状记忆回复应变从x=0时的5.0%降低到x=6时的2.0%.     

电子辐照CuZnAl形状记忆合金马氏体稳定化的研究

用能量 1.7MeV不同注量的电子辐照CuZnAl形状记忆合金样品 ,通过循环水冷的方法 ,将辐照控制在马氏体相进行 .实验结果表明 ,样品被辐照处理后 ,其马氏体相变温度和相变滞后 ,以及相变特征温度T0 都随辐照注量的增大而升高 ;当辐照注量在 6 .30× 10 2 0 m- 2 ～ 1.89×10 2 1m- 2 时 ,其相变温度变化渐趋平缓 .作者认为 ,这是由于电子辐照产生的点缺陷造成了马氏体相点阵畸变 ,从而诱生了马氏体稳定化     

CoMn合金中的马氏体相奕和形状记忆效应

研究了CoMn合金中的γγ(fcc)-ε(hcp)马氏体相关,并测量了合金的形状记忆效应（SME）,结果表明,该合金的马氏体相变具有典型的γ→ε马氏体相变体相变特征,它在发生马氏体相变时,内耗峰并不对应于母相模量的下降,其形核无需籍软模或区域软模,通过训练可以改善CoMn合金的SME,对改善的原因进行了初步的探讨。     

基于磁共振影像的乳腺癌计算机辅助检测方法综述

β钛合金具有良好的力学性能、高耐蚀性以及优异的生物相容性，在生物医用材料领域备受关注。β钛合金的超弹性归因于应力诱发的β→α"马氏体相变及其逆转变。阐述了影响β钛合金超弹性的因素，归纳了提高合金超弹性的方法。通过添加合金元素调整相变温度和滑移临界应力使得应力诱发马氏体相变更易发生，延迟β相塑性变形的发生，能够获得更大的相变应变和超弹性回复。通过优化热处理工艺和加工方法调控合金的相组成、晶粒尺寸、位错密度和织构等，也可提高合金的可回复应变，增强合金的超弹性。     

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