Mg-Sn合金化与固溶-时效行为的研究现状

作为具备良好发展前景的可时效强化镁合金，Mg-Sn合金通过Mg₂Sn相析出强化、固溶强化与细晶强化获得了优异的性能。与Mg-Zn、Mg-Al主要镁合金相比，Sn在Mg中的固溶度较好，析出强化效果优异；另外，Mg₂Sn相的熔点高达771.5 ℃，使Mg-Sn合金成为非稀土系列的低成本耐热镁合金。从合金化、固溶-时效处理工艺分析总结了可时效强化Mg-Sn合金的研究进展，分析Mg-Sn合金时效行为的重要参数及其影响因素，主要目的为细化Mg₂Sn析出相或增加Mg₂Sn析出相数量；同时，对添加到Mg-Sn合金中的合金元素的固溶效果、细晶效果与形成三元强化相效果进行系统总结与分析，为Mg-Sn合金成分的设计和性能改善提供重要参考。     

时效状态对Cu-Cr-Zr系合金性能的影响

采用不同时效状态和随后形变热处理工艺制备了Cu-Cr-Zr系合金,采用微观组织观察、硬度和导电率测试等手段研究了不同时效状态对双级时效Cu-Cr-Zr系合金性能的影响.结果表明：欠时效+冷轧+时效工艺和峰时效+冷轧+时效工艺制备的Cu-Cr-Zr-Mg-Si和Cu-Cr-Zr-Ni-Si合金均可获得力学性能和电学性能的优良组合.其中：欠时效+冷轧+时效工艺所制备的合金综合性能更优,但加工热处理过程中性能变化剧烈,材料生产过程中性能均匀性不易控制;峰时效+冷轧+时效工艺制备的合金综合性能极其稳定,易于在生产中控制.不同工艺下的合金性能差异是由析出相与位错的交互作用机制不同造成的.     

多级断续时效对Mg-Zn-Mn合金显微组织和力学性能的影响

为探索镁合金的多级时效工艺,利用Ｘ射线衍射、光学金相、扫描电镜以及能谱分析、透射电镜、显微硬度、力学性能测试等实验手段,研究了多级断续时效（T6I6）对ZM61新型镁合金显微组织和力学性能的影响。结果表明,与T6态相比,T6I6工艺更能显著提高合金强度,显微硬度为90HV,屈服强度为340Mpa,抗拉强度达到356Mpa,强度增幅分别为13%和8%;T6I6处理使合金晶间干净,第一级和第二级过程中只有Mn以α-Mn的形式继续析出,形成更多的Mn单质颗粒,终级时效的硬化幅度增加,且峰时效时析出了弥散分布的β'相,使强化效应得到充分发挥。     

Mg-Al合金非连续析出相改性的研究进展

Mg-Al合金因其密度低、比强度高、成本低廉,成为镁合金材料中被广泛应用的系列之一。然而,Mg-Al合金时效热处理过程中所存在的非连续析出行为恶化了其力学性能,限制了其进一步的应用。介绍了Mg-Al合金中非连续析出相的形成机制,进而从时效工艺调整和添加合金元素2个方面总结了目前改性或解决非连续析出行为的研究进展,最后对未来研究措施进行了简要展望,希望为Mg-Al合金材料的研究者提供借鉴。     

预变形对7N01铝合金力学性能及显微结构的影响

采用力学性能测量和显微结构表征和工艺调控等手段,系统研究了预变形加时效的组合工艺对7N01铝合金力学性能和显微结构的影响.研究表明:与单一的变形强化工艺和单一的时效强化工艺相比,合适的形变时效工艺能大幅提高材料的性能.本实验采用10%预变形后120℃再时效,合金的屈服强度可以达到430 MPa,抗拉强度可以达到470MPa,延伸率仍然保持在14%.随着预变形量的增加,合金的强度先上升后下降,采用过大的变形量反而不利于优化材料力学性能;变形引入的位错会对后续时效强化中纳米析出相颗粒的种类、尺寸和分布等产生关键作用,从而影响材料最终的综合力学性能.     

钇对铸态ZK60镁合金晶界析出相形态的影响

通过金相分析、扫描电镜(SEM)以及能谱(EDX)分析等实验手段,对Mg-6.0Zn-0.45Zr,Mg-6.0Zn-1.2Y和Mg-6.0Zn-0.6Zr-1.0Y三种合金铸态晶界析出相的形态进行了研究.实验结果表明,铸态Mg-6.0Zn-0.45Zr合金的晶界主要析出相是Mg-Zn二元相. 铸态Mg-6.0Zn-1.2Y合金与Mg-6.0Zn-0.6Zr-1.0Y合金的晶界析出相相似,主要以两种形态出现,一是在三角晶界形核,呈"鱼骨状",由Mg-Zn二元相和Mg-Zn-Y三元相组成;另一是几乎包围整个晶粒,呈连续网状,由Mg-Zn-Y三元相组成.另外,在含Y的合金中还发现,晶界析出相的边缘均有大量弥散的颗粒状析出物,颗粒呈辐射状向晶粒内部延伸分布.Y能强烈改变铸态Mg-Zn-Zr系合金(ZK60)的晶界析出相的形态.     

蠕变时效对Mg-8.8Gd-3.4Y-1.5Nd-0.5Zr合金力学性能和微观组织的影响

采用蠕变时效实验、维氏硬度、透射电子显微镜(TEM)和拉伸性能测试等手段研究蠕变时效在相同时间下对Mg-8.8Gd-3.4Y-1.5Nd-0.5Zr合金力学性能和显微组织影响。研究结果表明:Mg-8.8Gd-3.4Y-1.5Nd-0.5Zr合金蠕变时效时的稳态蠕变速率随着蠕变应力的增加与温度的升高而增大;蠕变时效能够细化析出相尺寸,加快合金时效析出相析出速率,从而缩短到达峰值时效的时间;外加应力会使合金β′相产生应力位向效应,导致合金形成β′相与β′e交错排列的链状析出相,应力位向效应对合金的力学性能产生不利影响。     

Al-Zn-Mg-Cu合金包覆淬火残余应力 与时效工艺研究

结合残余应力测量、原位电阻率表征、硬度测试和透射电子显微镜观察等探究了一种新型包覆淬火工艺及后续时效处理对Al-Zn-Mg-Cu合金板材微观组织和力学性能的影响.结果表明:包覆淬火工艺可以有效降低Al-Zn-Mg-Cu合金的淬火残余应力及位错密度,原位电阻率结果显示包覆层厚度越厚(0.2～0.6 mm),包覆淬火处理合金的时效析出行为与普通淬火合金越接近;通过原位电阻率和硬度测试获得了包覆淬火合金优化的峰值时效制度,在此时效处理条件下,包覆处理合金能够保持与普通水淬样品近似的析出显微组织及力学性能.     

Mg-Sm系合金的显微组织及力学性能

研究了Mg-(1%～3%)Sm(质量分数)合金在多种状态下的显微组织和力学性能.采用光学金相分析(OM),扫描电子显微分析(SEM),X射线衍射分析(XRD)等多种分析和测试手段,系统研究了挤压工艺及热处理(固溶处理、时效处理)对Mg-Sm系合金显微组织和力学性能的影响.结果显示,合金的铸态组织由a-Mg基体和Mg41Sm5组成.合金经热挤压加工后,Mg41Sm5相沿挤压方向呈纤维或颗粒状分布.在420℃挤压时,试样内发生了动态再结晶,致使挤压后合金的强度和塑性得到大幅度改善.固溶以及时效处理后,合金的性能比铸态有较大提高;而采用挤压后的直接时效(T5)处理,可获得良好的综合力学性能.因此,Sm可以考虑作为强化变形镁合金的添加元素.     

近固溶度高温析出对7055铝合金时效强化和应力腐蚀的影响

对7055合金采用先高温固溶后降温析出处理,通过光学显微镜、TEM观察和力学性能测试,分析了固溶后高温预析出处理对7055铝合金显微组织及力学性能的影响.研究结果表明:先高温固溶后再进行降温处理,在近固溶度条件下于晶界处产生预析出,并提高了后续时效状态下晶界析出相不连续分布的程度;这种预析出在保持高强度和高塑性的同时,可以改善合金的应力腐蚀抗力.     

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

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.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

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-