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991.
Generally, the good combination of pre-deformation and aging can improve the mechanical strength of the Al–Cu–Li–Mg alloys. However, the effects of pre-deformation on competitive precipitation relationship and precipitation strengthening have not been clarified in detail in Al–Cu–Li–Mg alloys with high Mg. In the present study, the effects of pre-deformation level on the microstructure and mechanical properties of an Al–2.95 Cu–1.55 Li–0.57 Mg–0.18 Zr alloy have been investigated. It is found that the introduction of dislocation by 5% pre-deformation can facilitate the precipitation of new successive composite precipitates and T _1 precipitates along the sub-grain boundaries or dislocations and inhibit the precipitation of dispersive GPB zones which is the main precipitates of the alloys without pre-deformation. The introduction of 5% pre-deformation can enhance the mechanical properties considerably. When the pre-deformation level increases from 5 to 15%, the number density of the successive composite precipitates and T _1 precipitates increases, and the aspect ratio of T _1 precipitates decreases. The decrease in T _1 precipitate aspect ratio and the increment of the successive composite precipitates result in the reduction in precipitation strengthening. Therefore, the increase in pre-deformation level from 5 to 15% does not further improve the mechanical properties of the alloys, although the dislocation strengthening increases continuously. 相似文献
992.
We present a structural study of Pt(3)Ni nanoctahedron superlattice, prepared through both drop-casting and controlled solvent evaporation approaches. In this superlattice system containing ~10.6 nm side-length Pt(3)Ni nanoctahedra, we observed a body-centered cubic (bcc) packing structure in both local superlattices and statistically averaged superlattice ensembles using transmission electron microscopic tomography and grazing-incidence small-angle X-ray scattering techniques, respectively. Within the superstructure, it was directly observed that nanoctahedra are orientated along the superstructure axes through sharing their vertices. We found that this arrangement of a bcc superstructure with nanoctahedra connecting through their vertices is dependent on neither the processing pathway nor the substrate under our experimental conditions. With such a very low packing density and ultrahigh surface area, this type of self-organized superstructure possesses unique features for future applications. 相似文献
993.
本文采用氯苯浸泡法对(0.2~2.0)μm的Al、Au溅射薄膜进行剥离,分析了光刻胶厚度和薄膜厚度与剥离图形的关系,对剥离过程中氯苯浸泡工艺以及溅射工艺对剥离图形的影响进行了研究,并在2.0μm厚的Al和Au溅射薄膜上剥离出8.0 μm的缝隙. 相似文献
994.
Single and multi-layer Cr/Cr2O3 coatings were deposited by reactive magnetron sputtering with the total thickness of 7 μm on steel substrates. X-ray diffraction analysis showed that single and multi-layer Cr/Cr2O3 coatings have different preferred crystal orientations. Columnar microstructure was detected by transmission electron microscopy both in metal chromium and ceramic chromium oxide layers. Grain size increased with the coating thickness. The value of single and multi-layer coating's fracture toughness is between 4 and 6 MPa·m1/2 measured with the Berkovich tip indentation, and it is between 2.8 and 3.9 MPa·m1/2 when measured with the Vickers indenter. The adhesion is about 192.1 and 246.7 J/m2 for single and multi-layer coatings, respectively. 相似文献
995.
996.
文章通过对江西省2个台站的地面气象观测业务无人值守改革试点运行期间出现的问题进行分析,相应地提出了针对性建议,为提高无人值守的仪器设备自动化及完善应急保障能力提供了参考。 相似文献
997.
用离子束溅射法制备了具有反常光吸收特性的纳米颗粒CU/SiO2复合薄膜。获得了在离子来参数一定时,基片温度、膜料的沉积时间和镀膜后的保温时间等工艺参数对这种薄膜结构和光学特性的影响规律,并对纳米颗粒Cu/SiO2复合薄膜的反常光吸收特性作了计算和解释。 相似文献
998.
999.
1000.
Mott–Schottky and photoelectrochemical measurements were used to explore the effects of hydrogen and chloride ions on the electronic properties of the passive film on X70 micro-alloyed steel in a solution of 0.5 M NaHCO3. Mott–Schottky analyses have shown that hydrogen increases the capacitance and donor density, and decreases the flat band potential and the space charge layer thickness of the passive film. The photocurrent of the film is remarkably increased by hydrogen. The effects of hydrogen become more pronounced with an increase in the hydrogen charging current densities. Hydrogen has no noticeable effect on the band gap energy Eg and the process by which hole-electron pairs are photo-generated in the film. The presence of chloride ions in the solution produces some similar effects on the electronic properties of the passive film to those observed with hydrogen, but reduces the photocurrent and increases the band gap energy of the film. No significant synergistic effects on the electronic properties of the passive film were observed in the presence of hydrogen and Cl−. These results provide very useful information for elucidating the mechanism by which hydrogen changes the properties of passive film and then promotes localized corrosion. 相似文献