GH4169合金锻造混晶组织的均匀细化机制与工艺

目的 消除GH4169合金锻造混晶组织,获得高品质GH4169合金锻件的制备工艺.方法 对变形后锻件进行后续的热处理退火,探明均匀细化锻造混晶组织的热处理工艺方法与机制.首先,设计并实施不同的单级退火工艺及双级退火工艺.随后,统计不同热处理退火工艺下锻造混晶组织的平均晶粒尺寸.最后,分析不同热处理退火工艺下混晶组织的细...     

GH4169合金变应变速率热变形过程动态再结晶动力学行为及建模

目的 研究变应变速率高温变形过程中GH4169合金动态再结晶行为和晶粒组织的演变机理.方法 在不同变应变速率工况下对GH4169合金进行高温压缩实验,分析了变形参数对动态再结晶行为与晶粒组织的影响规律,建立变应变速率工艺下GH4169动态再结晶动力学和晶粒尺寸预测模型.结果 随着第一阶段真应变的增加或第一阶段/第二阶段...     

MGH956合金冷轧薄板的高温再结晶行为研究

研究了MGH956合金冷轧薄板在高温（1300℃）热处理中的再结晶过程和晶粒组织发展演化的情况,认为MGH956合金冷轧薄板在1300℃高温热处理过程中会发生再结晶,高度变形的超细晶组织最终演变成为粗大的盘状晶粒组织;并且这种再结晶过程应该属于一次再结晶的范畴,而并非二次再结晶过程;再结晶过程结束后,继续延长热处理时间,晶粒组织不发生明显的变化。     

镍基合金完全再结晶后的晶粒长大行为研究

目的 研究镍基合金完全再结晶后的晶粒长大行为.方法 首先通过两道次热压缩实验获得镍合金完全再结晶组织,然后对完全再结晶的组织进行退火热处理使晶粒长大.采用电子背散射衍射实验研究发生长大的晶粒组织形貌与尺寸变化规律.结果 完全再结晶后的退火工艺参数对平均晶粒尺寸有显著影响.完全再结晶后的晶粒能够在较高的退火温度和较长的退...     

热处理对电沉积Ni-Fe合金箔组织和力学性能的影响

电沉积法制备Ni-Fe合金箔具有工艺简单,能耗低,产品规格不受限制等优点,但其塑性和弹性模量较低限制了其应用发展.为了改善电沉积Ni-Fe合金箔的力学性能并扩大其应用范围,本文通过高温热处理方法改善其力学性能,采用SEM,XRD,EBSD分析手段对电沉积Ni-Fe合金箔晶粒组织和结构进行了分析,通过高温热台显微镜进行原位在线观测晶粒组织的演变过程,并对热处理后的电沉积Ni-Fe合金箔进行力学性能分析.研究表明,热处理过程中电沉积Ni-Fe合金箔经历细晶组织阶段、混晶组织阶段和粗晶组织阶段,其中,在1 000~1 050℃容易发生晶粒异常长大.细晶组织阶段,电沉积Ni-Fe合金箔能够保证较高的强度,且塑性和弹性模量明显提高,综合性能较好;混晶组织阶段,强度和塑性较低,弹性模量有一定程度提高;粗晶组织阶段,强度很低,但塑性和弹性模量有较大程度提高.     

Aermet100钢高温变形动态再结晶晶粒演变行为

目的研究高温变形对合金动态再结晶晶粒尺寸的影响。方法利用Gleeble 3500热模拟试验机对Aermet100超高强度钢进行了热模拟压缩,分析了动态再结晶晶粒在变形温度为800~1040℃、应变速率为0.01~10 s-1条件下的演变行为。结果研究发现,Aermet100钢动态再结晶晶粒随变形温度的升高而增大,随应变速率的增大而减小,高温、低应变速率变形后获得的动态再结晶晶粒尺寸较大,再结晶充分;低温、高应变速率获得的动态再结晶晶粒尺寸细小,但再结晶不完全。结论根据实验数据,建立了动态再结晶晶粒尺寸随Zener-Hollomon参数变化的理论模型,为Aermet100钢锻造工艺优化提供了理论依据。     

Ti-Al-Sn-Zr-W-Si高温钛合金的蠕变性能

为大幅度拓展Ti-Al-Sn-Zr-W-Si高温钛合金的工程应用,优化了Ti-Al-Sn-Zr-W-Si高温钛合金的热处理工艺,研究了该钛合金的蠕变性能,并采用扫描电子显微镜观察了蠕变实验前后合金的微观组织特征及断口形貌。研究表明,经合理热处理工艺后,该合金在550和600℃均体现出优异的蠕变性能。蠕变实验后,合金的微观组织发生了明显的变化:在颈缩区呈明显的纤维状,而在均匀塑性变形区,由于回复再结晶,合金的显微组织呈现细小的晶粒。     

热处理制度对TC21钛合金锻件组织及力学性能的影响

研究了热处理制度对TC21钛合金锻件显微组织及室温、高温力学性能的影响,并与目前我国大量使用的TC11热强钛合金的同类锻件作了对比试验.研究表明,常规锻造工艺生产的TC21钛合金锻件,随着固溶温度的升高,显微组织中初生α相含量降低,室温塑性也随之变差,但高温抗拉强度、高温持久性能等随之升高,高温塑性变化不明显.通过常规锻造工艺加上合理的热处理制度,可获得适于高温环境使用的综合性能优异的TC21钛合金锻件.     

溅射镀膜用铌靶材晶粒尺寸控制工艺研究

铌靶材主要应用于表面工程材料,如船舶、化工、液晶显示器(LCD)以及耐热、耐腐蚀等镀膜行业。作为被溅射的基材,为了获得均匀一致的薄膜淀积速率,对溅射铌靶材的主要要求是均匀的组分、合适的颗粒尺寸以及具体的结晶学取向。本文主要研究在实际生产中,锻造工艺、轧制工艺以及热处理工艺对溅射镀膜用铌靶材晶粒尺寸的影响。通过多次试验,得到合理的锻造工艺、轧制工艺以及热处理工艺,从而对铸锭晶粒进行彻底的破碎和再结晶,最终得到晶粒尺寸小于100μm,且均匀一致的等轴晶组织,满足了溅射镀膜用铌靶材要求的晶粒尺寸和均匀等轴晶组织。     

全层片状组织的TiAl基合金高温塑性的研究

采用自制悬垂式流变拉伸机研究了ＴｉＡｌ基合金全层片状组织试样的高温塑性变形行为及过程。试验结果表明，在保持较稳定的应变速率工艺下，合金在９００℃的高温变形能力达７５．５％。动态再结晶促使γ相的形成，并在一定条件下导致混晶现象的出现。锯齿状晶界与混晶现象的存在，被认为是试样拉伸断裂的主要原因。     

Design for volume optimization of packaging for durable goods

In the literature, there are several authors arguing for the optimization of the packaging volume as an important factor in distribution efficiency. Within the context of packaging of durable goods, these authors present significant economic savings, usually illustrated by qualitative examples of redesigns. So far, these papers are limited to: (a) the economic aspect of volume (b) packaging for which the main functionality is distribution‐related, and (c) mostly qualitative empirical data. This current paper aims to contribute to this literature by: (a) arguing that volume is also a significant factor from an environmental perspective (b) including packaging for which the main functionality is marketing‐related, and (c) presenting quantitative data of over 1000 packed durable goods, covering consumer electronics, domestic appliances, toys, power tools and furniture. Several strategies for volume optimization are discussed in relation to different packaging functionalities. Copyright © 2011 John Wiley & Sons, Ltd.     

Concepts for on-orbit replenishment of liquid helium for SIRTF

The Space Infrared Telescope Facility (SIRTF) will be a large infrared observatory cooled to 2 K by 4000 dm³ of superfluid helium, and expected to have a lifetime of ≈2 years on orbit Concepts are presented for replenishing the cryogen on orbit, and for designing the airborne support equipment required. Replenishment starting with SIRTF either warm or cold, appears to be feasible within a Space Shuttle-based or Space Station-based mission.     

符合产品再生利用的设计：未来创造价值过程的基础

降低当前不断增长的资源消耗，这要求未来的产品循环在材料和能源方面更为有效。这将在保证技术先进的同时延长产品使用寿命和耐用性的基础上藉产品再生利用来实现。符合再生利用的产品必须具备开放式的系统结构，并且具有适合几个生命周期的动态的产品结构。为了此类产品的构造和设计，本文以机床为例，制订了支持设计的特殊规则和提示。在再生利用能力方面的设计质量可以用来有评价标准的清单予以检验。     

Model for prediction of processing window for austempered ductile iron

Abstract

A computer model has been developed to predict the processing window (austempering window) for austempered ductile iron (ADI). The model is a modification of an existing model for the isothermal decomposition of austenite in bainitic steels. It was calibrated using experimental data from the literature. In order to validate the model, the processing window corresponding to a ductile iron of composition 3.41%C, 2.46%Si, 0.36%Mn, 0.18%Mo, and 0.25%Cu is predicted and compared to experimental data. Computer assisted image analysis was used to investigate the volume fraction of martensite at the lower boundary of the processing window. X-ray diffraction was used to calculate the normalised volume fraction of austenite at the upper boundary of the processing window. The results show that the model successfully predicts the processing window corresponding to the iron investigated in this study.     

船舶与集装箱用钢板预处理过程中所用磨料的对比

对船舶与集装箱用钢板涂装前预处理过程中，抛（喷）丸清理（除锈、刻蚀）用各种磨料的性质、磨料硬度与侵入性及耐久性（寿命）的关系、磨料的形状与清理效果的关系、磨料的粒度与覆盖率、冲击功的关系作了对比分析，提出了合理选用磨料的原则。     

Optimum policy for warrants for and design of guardrails

An optimum policy for the warrants for and the design of guardrails based on benefit maximizing criteria is presented. It is shown that the strength, the number of classes of standards, and the location of guardrails should be determined simultaneously with due consideration for the nation-wide distribution of roadside dangers and the impact of colliding vehicles. Dynamic programming is used for optimization.     

Chemical methods for searching for evidence of extra-terrestrial life

This paper describes the chemical concepts used for the purpose of detecting life in extra-terrestrial situations. These methods, developed initially within the oil industry, have been used to determine when life began on Earth and for investigating the Moon and Mars via space missions. In the case of Mars, the Viking missions led to the realization that we had meteorites from Mars on Earth. The study of Martian meteorites in the laboratory provides tantalizing clues for life on Mars in both the ancient and recent past. Meteorite analyses led to the launch of the Beagle 2 spacecraft, which was designed to prove that life-detection results obtained on Earth were authentic and not confused by terrestrial contamination. Some suggestions are made for future work.