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71.
Li Li 《Materials Science and Engineering: A》2011,528(24):7178-7185
Microstructural evolution and texture of a cast Mg-9Gd-4Y-0.6Zr ingot under hot compression were studied in this paper. Post-deforming microstructures were characterized by optical microscopy, scanning electron microscopy and transmission electron microscopy, while crystallographic orientation information was obtained from X-Ray macro-texture measurement and EBSD micro-texture analysis. Dynamic recrystallization (DRX) initiated from the deformation bands (DB) forming on original grain boundaries; the DB became widen with continuously conversion of low-angle-boundary grains into high-angle-boundary grains. The tendency of strain localization increased with Z parameter. The macro-texture analysis indicates that uniaxial compression yielded out the randomized basal texture component. This texture component was found to be strengthened with increasing Z parameter. The micro-texture analysis shows that the deviation from the ideal basal texture arose from orientated growth within DBs. Moreover, the localization deformation promoted dynamic precipitation within DBs, which inhibited the development of DRX. 相似文献
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73.
Z.M. Wang 《Corrosion Science》2010,52(4):1342-1350
A model metallic glass Ni50Nb50, which would undergo a polymorphous transformation during devitrification, was selected to clarify the correlation of amorphous structure with corrosion. The electrochemical polarization behaviour, film breakdown and composition of surface film have been studied in detail by comparing the amorphous alloy with its crystalline counterparts. Interestingly, it was found that the pit initiation is inhibited greatly on amorphous sample relative to the crystallized one. The origin is thought to be related to the defective interface beneath passive film that inhibits the formation of pitting precursors in corrosion. 相似文献
74.
Small punch tests (SPTs) have been carried out at room temperature to correlate the microstructural variation of Ti–6Al–4V alloy with that of SPT parameters. Microstructural variation in terms of different volume fractions of primary alpha phase of Ti–6Al–4V alloy has been introduced as a result of solution annealing at different temperatures followed by thermal aging. Small punch test parameters, i.e. total area under the load vs displacement curve, area under the zone of elastic bending, plastic bending and plastic instability have been found to increase from the content of 10% primary alpha phase to 20% primary alpha phase and then these are decreasing from the content of 20% primary alpha phase to 30% primary alpha phase. 相似文献
75.
《Journal of the European Ceramic Society》2020,40(8):3222-3234
A novel phenomenon is found that the grain growth of aluminum-rich magnesium aluminate is suppressed to 5 μm, despite of high-temperature hot-isostatic-press at 1750 °C. For the transparent MgO-nAl2O3 (n = 1.2, 1.5, 2.0), the transmittance and strength tended to be enhanced with increasing Al2O3 content, having the highest values 80 % at 550 nm and 214.3 MPa for n = 2.0. This is due to the different microstructural evolution depending on the composition. When the excessive Al2O3 was small, the inhomogeneous microstructure with bimodal grain size and lots of rod-shaped particles were observed. However, as the Al2O3 amount increased, the microstructure became homogeneous with reducing the grain size and the rod-shaped particles. The microstructural and compositional analysis revealed that the rod-shaped particle were generated due to the trace potassium impurity as well as the different cationic diffusion rate, and the suppression of grain growth was induced by the severe Al segregation at the grain-boundaries. 相似文献
76.
以碳酸镁和硼酸为原料在高温条件下合成了基质材料MgB4O7并制备了MgB4O7∶Dy磷光体.用RGD-3热释光剂量仪和三维热释光谱仪分别测量了这种磷光体的二维发光曲线和三维发光谱,实验观察到:1)MgB4O7∶Dy磷光体热释光发光峰峰温为220 ℃和380 ℃;2)Dy3 离子的发光波长为480 nm、575 nm和660 nm;3)磷光体220 ℃和380 ℃发光峰的相对强度随高温固相反应温度的升高而变化,但发光峰温和波长基本保持不变.对比MgB4O7∶Dy和MgSO4∶Dy两种热释光材料的三维发光谱,验证了掺入Dy3 离子的热释光材料的发光峰峰温主要由基质材料决定,发光波长则取决于Dy3 离子的能级跃迁的结果. 相似文献
77.
78.
聚碳酸酯合金的研究现状 总被引:6,自引:0,他引:6
概述了PC/ABS、PC/PE、PC/PS、PC/PET、PC/PA等合金的增容方法、增容后合金的结构与性能、不同PC合金性能的优缺点,讨论了PC合金化研究中存在的问题以及可能的解决方法。 相似文献
79.
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