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951.
Laser shock-processing for fatigue and fracture resistance 总被引:1,自引:0,他引:1
The generation mechanism of stress wave induced by laser-shocking is described and the stress wave is measured with a PVDF transducer. The visual inspections and control methods of the effectiveness of laser shock-processing (LSP) are built up. A small-sized, Q switched Nd: glass laser with high-power is used for LSP The fa tigue lives of aluminum alloy are increased greatly after LSP. With 95% confidence, the mean fatigue life of 2024T62 aluminum alloy after the LSP is 4. 5-9. 8 times that of the un-shocked ones The hardness, microstructure and fracture section of materials are analysed before and after LSP. The anti-fatigue and anti-fracture mechanism is analysed and the prospects of wide applications of LSP technology are described 相似文献
952.
A sort of special dislocation configuration was deformation-induced in an Fe-Ni-V-C alloy by in-situ elongation tests of TEM. The cooling in-situ observations, as well as the SADPs from the region of the special dislocation configurations, proved that they are martensitic nuclei. In martensitic transformation, a nucleus changed into a small martensitic sub-plate, and a group of parallel sub-plates that formed from a group of parallel nuclei made up a big martensitic plate Martensitic transformation involved opposite shear between adjacent martensitic nuclei. By using the reduced-cell method, the crystallographic structure of observed martensitic nuclei was indexed as a face-centered orthogonal (FCO) lattice, which was explained by the nucleation mechanism proposed by the present authors. The crystallographic analysis confirmed that the defect faulting involved in martensitic nucleation took place among three close pakked planes, instead of between two adjacent planes as an ordinary stacking fault. 相似文献
953.
利用Gleeble-1500焊接热模拟试验机,在固定的加热速度(150℃/s)、峰值温度保温时间(7s)与800~500℃冷却时间为7s的条件下,研究了峰值温度(Tm)在1050~850℃内变化对低合金奥-贝球墨铸铁热影响区组织及力学性能的影响。研究结果表明,随Tm的增高,高碳马氏体占基体组织百分数增加,马氏体片随之增长、变粗,σb和αk值显著下降,同时分析了共晶团各点马氏体含碳量不同,点阵畸变程度发生变化的原因 相似文献
954.
反应型相容剂含有反应基团,可与含相应基团的聚合物起化学反应,因而在混炼过程中增容。本文系统地介绍各种反应型相容剂的设计、合成、品种和应用。 相似文献
955.
本文重点研究了锡锌合金镀层(含锌25%左右)的铬酸盐钝化液中活化剂和硬化剂的作用,以及钝化工艺条件的影响。研制了比较理想的钝化液的组成和工艺条件,得到了彩虹色钝化膜,并具有良好的耐蚀性。 相似文献
956.
957.
958.
In this work, the behaviour of a CoCrMo alloy under simulated body conditions was investigated. More specifically, the electrochemical properties of the alloy and the relevant mechanisms in the passive and transpassive states were studied in detail. Electrochemical techniques such as potentiodynamic and potentiostatic polarisation, cyclic voltammetry, rotating disc electrode and electrochemical impedance spectroscopy were employed. Further, ex situ X-ray photoelectron spectroscopy analysis of the passive films was carried out. A good correlation between the results obtained from all the experimental techniques was achieved. Overall, it was found that the passive film on CoCrMo changed in composition and thickness with both potential and time. The passive behaviour of the CrCrMo alloy is due to a formation an oxide film highly enriched with Cr (≈90% Cr oxides) on the alloy surface. The passive and transpassive behaviour of the alloy is hence dominated by the alloying element Cr. In the transpassive region, strong thickening of the oxide film takes place, combined with a change in the composition of the film, and strongly increased dissolution rate. In the transpassive region, all alloying elements dissolve according to the composition of the alloy. The metal ion release is also very strongly enhanced by cyclic variation of the potential between reducing and oxidizing conditions. In this case, during activation/repassivation cycles, cobalt dissolution is greater than expected from the composition of the alloy. Therefore, active dissolution behaviour is mainly dominated by the alloying element Co. 相似文献
959.
制氢方法及储氢材料研制进展 总被引:9,自引:0,他引:9
王景儒 《化学推进剂与高分子材料》2004,2(2):13-18
随着环境保护意识的日益增强和石油、煤资源的日渐枯竭 ,寻找新的洁净能源已列入人们的议事日程。氢就是一种洁净能源。介绍氢的各种制备方法及近年来储氢材料的研制进展 ,并阐述氢及储氢材料的应用领域。 相似文献
960.
通过X射线衍射谱(XRD)、气态吸放氢行为(PCT曲线)、电化学充放电性能、电化学阻抗谱(EIS),考察了Ni添加对Ti_(0.47)V_(0.28)Mn_(0.15)Cr_(0.1)储氢合金的电化学性能的影响。结果表明:Ti_(0.47)V_(0.28)Mn_(0.15)Cr_(0.1)的电化学活性很差,在碱液中几乎不能放电,添加Ni之后得到了明显改善。随着Ni含量的增加,Ti_(0.47)V_(0.28)Mn_(0.15)Cr_(0.1)Ni_x(x=0~0.25)合金电极的放电容量先增大后减小,在x=0.15时达到最大值310mA·h·g~(-1)。 相似文献