TiH2粉末制备钛合金的烧结脱氢规律及工艺

 以TiH₂粉末为原料,通过压制成型和烧结工艺制备粉末钛合金,不同于传统钛粉末冶金方法。通过热分析和热膨胀技术研究不同球磨粒度TiH₂粉末的脱氢和收缩规律,以此入手研究了TiH₂粉末压坯和TiH₂-Al-V粉末压坯的烧结致密特性,以及影响烧结过程的主要工艺因素,包括烧结温度、烧结时间、升温速率、压坯密度、压坯成型方式、合金体系,并对烧结组织进行了分析。结果表明,TiH₂粉末球磨后脱氢温度降低,粉末越细,开始温度越低。TiH₂粉末压坯在烧结过程中脱氢后获得新鲜钛,其易发生黏接并引起α-Ti的强烈收缩,这时烧结体很容易致密,并获得相对密度大于99%坯体;相比之下,TiH₂-Al-V粉末压坯烧结时因为合金元素的溶解,不如纯TiH₂粉末压坯的烧结容易致密。TiH₂-Al-V粉末经过成型、烧结脱氢可获得典型的层片状α+β钛合金组织,合金元素分布均匀。     

弥散强化铜致密化研究

本文对Cu-0.86V％Al_2O_3弥散强化钢(DSCu)粉末坯进行了四种致密化方法的研究和比较。讨论和观察了致密化过程中温度、压力的功能和形貌变化。认为:(1)DSCu粉末坯锭致密化应包括坯块密度的提高和颗粒结合状态的改变;(2)DSCu宜采用有应力烧结。采用致密化坯锭挤压。可使DSCu材料成品率提高20％以上。     

粉末铁基高温合金的制备工艺研究

采用粉末机械合金化-温压成型-真空烧结等方法制备了氧化物弥散强化铁基高温合金MA956,并对其制备工艺和组织性能进行了研究。结果表明,高能振动球磨4h粉末颗粒细小均匀,已经基本实现了合金化,将其在120℃、500MPa条件下进行温压成型,压坯密度比常温模压工艺提高了0．3g／cm3;烧结温度对烧结体组织和性能有较大的影响,粉末压坯在1350℃烧结其致密度最高,为90．8％,且显微组织致密性好。     

3Cr13粉末不锈钢的研究

采用球磨、粉末热处理、合金化及活化烧结工艺对 3Cr13粉末不锈钢性能进行了研究。结果表明,3Cr13 不锈钢粉末经 6 h 球磨,860 ℃预处理及加 2 wt％Cu可改善其压制性,提高压坯密度及烧结性能。3Cr13 粉末不锈钢在硬度、压溃方面优于实体不锈钢,用其制作水泵轴套材料是可能的。     

细晶Mo-40%Cu合金的烧结性能

采用溶胶—喷雾干燥—煅烧—氢还原工艺制取纳米晶Mo-40%Cu(质量分数)复合粉末,并利用该粉末制备具有优良物理力学性能的细晶Mo-40%Cu合金。研究烧结温度、时间对合金性能的影响,检测合金的物理力学性能,分析合金的显微组织与断口形貌特征。研究结果表明:采用该法制取的纳米晶Mo-40%Cu复合粉末烧结活性高,其成形压坯在1 050～1 100℃于H2气氛中烧结保温60 min即可实现材料的快速致密化,合金的相对密度可达到98%以上,最大拉伸强度和伸长率分别为630 MPa和6.97%,且组织晶粒细小(平均粒径小于1μm)。     

Ti-47．5Al-2．5V-1．0Cr注射成形

以Ti-47.5Al-2.5V-1.0Cr(原子分数,%)气雾化预合金粉末为原料,采用粉末注射成形工艺制备了TiAl合金材料,研究了该TiAl合金脱脂工艺对脱脂坯碳氧残留量和组织的影响规律及烧结工艺对烧结体显微组织、密度和压缩性能的影响规律. 结果表明:在脱脂温度600℃、保温时间为1h和真空脱脂气氛条件下脱除坯体中剩余粘结剂,坯体中残余碳氧含量(质量分数)分别为0.059%和0.12%;脱脂温度从600℃升到1000℃,粉末由枝状组织转变为近γ组织;烧结温度在1410～1450℃,保温时间在1h以内,烧结体可以快速致密化;在1450℃保温30min,烧结体相对密度可以达到95%,烧结体的抗压强度为2105MPa,压缩率达到30.9%,接近铸态合金力学性能;随烧结温度升高,烧结体中的γ相逐渐减少,组织由近片层组织逐渐转变为全片层组织.     

SPS烧结TiO2／Al90Mn9Ce1微胞陶瓷金属基块体复合材料

用表面包覆8wt％TiO2纳米粉末的微米Al90Mn9Ce1合金复合粉末，制备了高致密的闭合微胞陶瓷结构，内充金属合金的块体复合材料，烧结温度仅为520℃，烧结后的致密度达到98．2％。SEM观察结果显示，该材料的陶瓷胞壁厚度约为1．0～2．0μm，胞体尺寸约为15～40μm，经10％HCl深腐蚀后，留下完整的微胞状陶瓷骨架。根据实验结果，对SPS烧结微-纳米混合粉体的瞬时界面烧结机理进行探讨。     

一种烧结铁基合金Fe-Cr-Mo-Ni-Co-C的热致密化过程

利用金相、扫描电镜和密度测试等方法研究Fe-Cr-Mo-Ni-Co-C合金的致密化过程，烧结过程中烧结密度与压实密度的关系，烧结致密化过程中孔隙的变化规律与烧结体积的收缩规律。通过研究舍金烧结体积的收缩规律，提出临界压坯密度的概念，并从理论上推导出临界压坯密度计算方程。研究结果表明：合金中的孔隙主要有2种类型，即粒径为30μm左右的大孔隙和粒径在10μm以下的小孔隙，这2种孔隙分别由生坯中的2种主要间隙在烧结过程中演变而成。     

烧结压力对Al90Mn9Ce1合金SPS致密化的影响

采用放电等离子烧结（SPS）技术,在50MPa,300MPa,600MPa单轴压力下,对固结气雾化法制备的粒度为20-45μm的Al90Mn9Ce1合金粉末,研究了压力和脉冲电流作用下的致密化过程。结果表明,提高烧结压力有助于粉末的塑性变形和幂率蠕变,促进Al90Mn9Ce1合金压坯的致密化。当烧结压力为600MPa时,在660K保温0min条件下,样品致密度达到99．2％,强度达到1048．5MPa,原始颗粒之间形成宽度为20nm的熔合区,界面结合良好。     

机械活化Mo－Cu粉末的烧结

研究了Ｍｏ－Ｃｕ粉末，经机械活化处理后的组织、形态与液相烧结性能、合金组织的关系，实验结果表明：一定时间活化处理，Ｍｏ－Ｃｕ粉末形成机械合金化初期的层状组织，其压坯可在较低温度液相烧结，合金相对密度大于９９％，组织细小、均匀。     

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-