时效对00Cr13Ni6Mo马氏体不锈钢韧性和断裂的影响

研究了添加Nb和Ti的马氏体时效不锈钢在不同的时效工艺下脆性产生的规律和断裂表面特征 ,对脆化本质进行探讨 ,并讨论了断口剪切区面积与韧性的关系 ,以及合金元素、时效过程与断裂方式之间的关系。     

A STUDY ON KINETICS OF AGING OF PAVING ASPHALT

In this paper the aging processes of two penetration-grade paving asphalt which conform to the standard of Esson Company have been studied by rotation thin film oven (RTFO). The first order aging kinetic model has been established and some kinetics parameters were calculated. The relationship between pavement properties of asphalt and aging course was revealed. The intervention of oxygen in high temperature caused oxidation reactions, which changed the composition and structure of asphalt, the aging resistant performance of asphalt was weak, and the service performance went to bad.     

时效对Au－39．8Cu－21．0Zn－3．2Al形状记忆合金的影响

用电阻法研究了不同时效条件对标题合金的马氏体转变温度和形状记忆效应的影响。结果表明：经分级淬火处理的合金，有较高的热稳定性和良好的形状记忆效应。但在高于１２０℃的温度时效一定时间后，将严重影响合金的马氏体相变，从而使合金丧失形状记忆效应。     

Modeling and analysis of rapid catalyst aging cycles

The primary mode of deactivation of automotive emission control catalysts is thermal aging, and it is well-known that high-temperature lean aging conditions are particularly detrimental. Since evaluating the long-term durability of automotive catalysts is costly and time-consuming, rapid catalyst aging cycles have been developed to mimic (in a reduced time) the catalyst deactivation under real-world driving conditions. One of the commonly used rapid catalyst aging tests is an exothermal aging cycle, which involves a combination of fuel-rich engine operation and supplemental air injection to generate high-temperature lean conditions within the catalyst bed. In this work, we use the previously developed transient three-way catalyst model to investigate the time evolution of the axial temperature profiles and exhaust air–fuel ratio (A/F) along the catalyst bed during the course of the exothermal rapid aging cycles. We find that the thermal front propagates downstream through the catalyst bed relatively slowly (compared to the concentration front) and this can limit the location within the catalyst bed and duration for high-temperature lean exposure. We also investigate how variations of some of the key system design and operating parameters can affect the extent and duration of high-temperature lean exposure. Finally, a simple analytical expression is developed which allows one to estimate the time it takes for the thermal front to travel through the catalyst bed. This time can be compared with the period of the lean A/F operation during the aging cycle to determine the location and duration of high-temperature lean exposure.     

Influence of aging behavior of Armos fiber after oxygen plasma treatment on its composite interfacial properties

This work concerns the aging behavior of Armos fiber and Armos fiber reinforced poly (phthalazinone ether sulfone ketone) (PPESK) composite after oxygen plasma treatment. Armos fiber surface chemical composition, surface morphology and roughness, and surface wettability as a function of storage time in air after oxygen plasma treatment were measured by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and dynamic contact angle analysis (DCAA) system, respectively. The fiber surface aging behavior could be detected obviously in chemical composition and surface wettability, whereas the surface morphology and roughness remained nearly stable after storing in air as long as 10 days after oxygen plasma treatment. The effects of surface aging behavior after oxygen plasma treatment on Armos fiber reinforced PPESK composite interfacial properties were evaluated by interlaminar shear strength (ILSS) test and humid resistance measurement. It was found that the values of ILSS reduced and the composite humid resistance properties decayed. The polar functional groups that were reoriented from the surface into the bulk of the fibers or moved away from the fiber surfaces, maybe responsible for the weak interfacial strength between the fiber and the matrix in composite system.     

Aging of oily soils on textiles. Chemical changes upon oxidation and interaction with textile fibers

Aging of unsaturated oily soils on textile materials produces yellow compounds that are difficult to remove by washing. To investigate changes that occur in oily soils when aged, the aging of squalene and artificial sebum were studied. Proton nuclear magnetic resonance, infrated spectroscopy, gas chromatography, and gel permeation chromatography studies showed that oily soils were oxidized upon aging, forming low molecular weight products that also polymerized to higher molecular weight compounds with prolonged aging. The oxidation products contained hydroxyl, carbonyl, or ester groups. Oxidation compounds with yellow chromophores appeared to be mostly those of the 1000–2500 molecular weight fraction; though in earlier, stages of aging, lower molecular weight fractions also contained chromophores. By using glucose as a model compound of cellulose, it was found that yellow oxidation products of aged squalene were covalently bound to the substrate. Because the aging of oily soils is a free-radical oxidation process, oxidation products having chromophores are thought to attach to the cotton substrate through radical coupling. Oily soils also showed possibilities of chemical bonding with nylon but not with polyester.     

Effect of Delamination on Mechanical Properties of Al-Li Alloy Modified by Rare Earth Element Ce

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时效处理对Fv520（B）钢抗H2S应力腐蚀性能的影响

采用Ｘ射线衍射 ,ＴＥＭ、ＳＥＭ等研究了时效温度对Ｆｖ５２０（Ｂ）钢组织、力学性能及抗Ｈ２Ｓ应力腐蚀性能的影响。结果表明：在４７０－６２０℃时效温度范围内,随温度升高,该钢的强度下降,残余奥氏体含量增加,抗Ｈ２Ｓ应力腐蚀能力增强。该钢抗Ｈ２Ｓ应力腐蚀性能与时效相形态,马氏体基体回火程度及残余奥氏体数量有关。     

Temperature Gradient Induced Orientation Change of Bi Grains in Sn-Bi57-Ag0.7 Solder Joint

Sn-Bi-X solders are widely used in electronic packaging industry. However, thermomigration (TM) behaviors of Sn-Bi-X solder joints and the orientations change of Bi grains under the temperature gradient are rarely reported. In this study, Sn-Bi57-Ag0.7/Cu solder joints were used to conduct a TM test under a temperature gradient of 625 °C/cm for 400 h, and an isothermal aging test at 85 °C was also conducted for comparison. The microstructural evolution of Sn-Bi-X solder joints after reflow, TM and isothermal aging were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron probe microanalysis (EPMA). The results indicated that the Sn/Bi areal ratio after TM did not change significantly whether at the hot end (from 46.78%/52.12% to 50.90%/48.78%) or at the cold end (from 50.25%/49.64% to 48.71%/51.16%) compared with that of as-reflowed samples due to the insufficient thermal energy. The thickness of intermetallic compound (IMC) after TM at hot end (2.49 μm) was very close to that of the IMC at cold end (2.52 μm), which was also close to that of the aged samples. In addition, the preferred orientations of Sn and Bi grains in different Sn-Bi-Ag solder joints resulting from different conditions (reflow, TM and isothermal aging) were characterized by electron backscatter diffraction (EBSD). The obtained results demonstrated that both Sn and Bi grains had no preferred orientation whether after reflow or isothermal aging, while the orientation of Bi grains of the sample after TM changed from random direction to c-axis ([0001] direction) parallel to the heat flow. Ag₃Sn could hinder the change of orientation of Bi grains under the temperature gradient, and the corresponding mechanism was also systematically illuminated. This study firstly revealed the orientation change of Bi grains under the temperature gradient, which would have a profound guiding significance for enhancing the reliabilities of Sn-Bi-Ag solder joints.     

时效温度对非调质钢MFT8拉伸性能的影响

介绍了试验材料及方法,对冷拔非调质钢MFT8在不同温度下进行了时效处理,对试验结果进行了分析研究。分析结果表明,MFT8非调质钢具有较强的加工硬化能力,冷拔MFT8非调质钢经300℃时效后具有最佳的强度和塑性配合。