一种单晶高温合金中g?相的析出行为

研究了固溶冷却速度和时效时间对一种镍基单晶高温合金中γ′相的析出的影响。合金经1 250℃固溶处理4 h,从炉中快速取出,分别进行空冷、油冷和水冷,以考察冷却速度对γ′相析出的影响。随后对固溶处理后试样进行时效处理,以考察时效时间和固溶冷却速度对γ′相长大的影响。结果表明,合金在固溶处理后,γ′相尺寸随固溶冷却速率的升高而下降。在时效处理时,γ′相尺寸的增大率随固溶冷却速度的增大而减小;随着时效时间的增加,γ′相的尺寸增加。     

热处理工艺对热挤压变形粉末高温合金FGH95组织与性能的影响

对比研究了FGH95合金在不同热加工工艺和热处理制度下合金的组织及γ′的分布,用光学显微镜、扫描电镜(SEM)和透射电镜(TEM)观察了不同热处理制度处理后合金的组织及时效后γ′的中心暗场相,测试了室温(20℃)和高温(650℃)材料的拉伸性能,并对高温瞬时断裂区断口进行了对比分析. 结果表明:相同热处理工艺,HIP温度越高,时效析出的γ′相尺寸越大;不同热处理制度均能够改变γ′的分布;盐浴冷却明显增大中等尺寸γ′相数量,显著提高合金高温塑性.     

热处理对第二代镍基单晶合金DD11显微组织及持久性能的影响

采用光学显微镜和扫描电镜对铸态、固溶态和时效态的第二代镍基单晶合金DD11的显微组织进行定量表征,并测试了不同一级时效处理后的合金1 100℃/140MPa和980℃/250MPa条件下的持久性能。结果表明:合金经过1 320℃/6h固溶处理后,(γ+γ′)共晶相全部溶解,凝固偏析显著降低,合金组织均匀。一级时效温度低于1 160℃时,γ′相为方形,一级时效温度高于1 180℃时,γ′相为球形,γ通道显著变宽,并在通道内析出细小的γ′相。随一级时效温度提高,合金的持久寿命先增大后降低。持久性能与γ′相尺寸、体积分数及形态密切相关。     

亚固溶温度热处理对GH720Li难变形高温合金γ′相的影响

对难变形镍基高温合金GH720Li进行了亚固溶处理、亚固溶+单时效(650℃,24 h→空冷)或双时效处理(650℃,24 h→空冷+760℃,16 h→空冷)以及870℃时效3000 h条件下γ′相演变规律的研究.发现一次γ′相受亚固溶处理影响较大,发生部分回溶的程度随固溶温度升高而增大,时效处理使一次γ′相向球形或近球形转变;二次和三次γ′相在亚固溶保温过程中完全回溶,在时效处理时补充析出明显且析出数量和区域随固溶温度升高而增大;870℃长期时效时,合金组织逐渐均匀,二次和三次γ′相完全回溶,晶界一次γ′相时效500 h后有所粗化,合金硬度先降低而后保持不变.     

镍基高温合金长期时效后γ′相长大动力学

采用TEM观察,相分析,图像分析等实验方法,对合金在873～1173K分别经100～1000h长期时效处理,研究了γ′相的长大动力学·结果表明,γ′相随温度的升高和时间的延长明显长大,但温度的影响比时间更为明显·在一定温度下随时间延长其长大规律符合里夫希茨·瓦格纳的成熟理论:r3与t成正比,γ′相长期时效的长大速率相对于时效初期的长大速率较慢,组织比较稳定·根据试验结果利用作图法得出合金的扩散激活能为241 54kJ·mol-1·     

ZA27合金自然时效过程的研究

砂型铸造 ZA27合金强度高,塑性低,通过淬火后自然时效,不但使强度有所提高,而且使塑性大为改善。通过透射电镜金属薄膜分析,ZA27合金时效中,金相结构转变过程为:α过饱和固溶体→G·PI 区→G-PI 区→γ′过渡相→γ稳定相。     

Co-Al-W三元合金热处理组织

研究不同Al和W含量对四种Co-Al-W三元合金的初熔温度、热处理组织和硬度的影响. 结果表明:四种Co-Al-W三元合金的固、液相点温度均超过镍基单晶高温合金液相点温度;在1300℃/8h固溶处理后,三种合金均仅得到γ(fcc)单相组织,而高W合金在晶界和晶内均有μ相Co7W6析出;在800℃/100h和900℃/50h时效处理后,四种合金在基体γ相中均析出L12型γ′相Co3(Al,W),其γ+γ′两相组织形貌与镍基高温合金相似;高W(12%)和高Al(12%)合金分别促进了μ相Co7W6和富Al相析出. 综合以上结果并结合时效合金的硬度结果,初步确定了含γ+γ′两相组织的合金成分范围.     

一种新型镍基合金相的析出规律

采用物相分析和透射电镜(TEM)方法研究了GH4199合金中不同温度长期时效处理条件下相的析出规律·结果表明,合金经长期时效处理后γ′相在700～800℃时析出比较充分,800℃以上开始回溶,γ′相在高温长期时效过程中的长大规律符合Ostwald理论,同时合金中有TCP相的析出·GH4199合金电子空位数为2 31到2 35,比镍基合金中μ相析出的临界电子空位数2 30略大,故当合金在高温下具有足够的热暴露时μ相会析出;合金的电子空位数虽不高于σ相析出的临界值,但由于γ′相的大量析出,造成合金基体中的Cr,Mo等形成σ相元素局部相对含量剧增,有可能导致σ相析出·     

GH220合金的基本组织

GH220合金正常热处理组织有γ基体。γ′、MC、M_6C和M_3B_2相。第一阶段晶粒长大温度1150℃—1170℃,第二阶段为1210℃。碳化物相M_6C最大析出峰在1000℃左右,并发现不同成分的二种M_6C相。 正常热处理得不到大小二种γ′,等温弯晶热处理能得到大小γ′和弯曲晶界组织。 长期时效,低W、Mo、Al、Ti(17.61％)合金析出M_(23)C_6相。当W+Mo大于12％(如12.31％)正常热处理会析出少量μ相;等于12％时,时效后才出现μ相。 合金中加入微量元素Mg可改变碳化物形状,使之细化。     

新型钴基高温合金γ和γ′相行为的热力学分析

采用热力学分析方法,对新型钴基高温合金Co-Ni-Al-W-Cr多元系中γ′相的析出规律进行了研究,分析了合金元素Ni,Al,W在γ和γ′相间的分配行为,阐述了Ni在γ和γ′相间的分配系数对合金强化效果的影响规律.结果表明:合金元素Ni明显提高γ′相热力学稳定性,随Ni含量的增加,γ′相的成分范围扩大,定存在温度提高,说明Ni有利于提高Co-Al-W基高温合金的高温性能;计算分析了合金元素在γ和γ′相间分配行为及其对合金强化的影响规律.探明Co-Ni-Al-W-Cr合金中x(Al)/x(W)对合金元素Ni的分配系数KγN′i/γ影响较大,当Al,W原子分数比值为2.60时,KγN′i/γ达到最...     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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