排序方式: 共有24条查询结果,搜索用时 31 毫秒
1.
对Al_2O_3颗粒增强铝复合材料与K_2Ti_5O_(13)晶须增强铝复合材料中的增强相/金属界面区域点阵位移场进行CBED研究,并对其进行电子衍射动力学理论模拟计算,结果表明:表面弛豫效应对晶须/铝界面法线方向上位移分量大小的分布影响显著,而对界面切线方向上位移分量的影响很小。这一结果对于解决CBED法测量界面应变场时遇到的表面弛豫效应问题是有意义的。 相似文献
2.
Effect of Fe3O4 segregation at grain boundaries on the electrical transport and magnetic properties of La0.67Ca0.33MnO3 is investigated. The experimental results show that the Fe3O4 segregation not only shifts the paramagnetic-ferromagnetic transition temperature of La0.6TCa0.33MnO3 to a lower temperature region but also induces a new transition in a lower temperature region. Meanwhile, the transition processes observed in both the resistivity and magnetization curves are obviously widened. Compared to pure La0.67Ca0.33MnO3, we assume that the Fe3O4 segregation level at the grain boundaries can modify the electrical transport and magnetic properties of La0.67Ca0.33MnO3. 相似文献
3.
Three-dimensional size and orientation of the precipitates in AZ91 magnesium alloys measured by TEM techniques
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Knowledge of the microscopic structure, including three-dimensional
(3-D) size and orientation of the precipitates, is essential to
fully understand the mechanical properties of the magnesium
alloys and designing the alloys with better performance. Analytical
TEM with high spatial resolution offers the simultaneous
measurements of 3-D size, structure, orientation, composition of the
precipitates from one typical sample along an established
crystallographic axis. Besides popular Burgers orientation
relationship (OR), other ORs such as Pitsch--Schrader OR, Crawley
OR, Potter OR and a new OR with the form of [0001]α
1.0° from [311]γ and (11\bar 20)α
2.0° from (03\bar 3)γ between the magnesium
matrix and the precipitate γ -Mg17Al12 are
identified by TEM imaging and diffraction techniques. As a case study,
the thicknesses of the individual precipitates with Burgers OR are
further measured to be 100--200~nm through both electron energy-loss
spectroscopy and x-ray energy dispersive spectroscopy combining
differential x-ray absorption and extrapolation, which are in
agreement with the overall 3-D size statistic distribution results
obtained through analysing various samples along various directions.
Furthermore, the fabricated wedge-shape structure provides a
platform on which to study the dependence of the interfacial strain on the
variation of the thickness. 相似文献
4.
尖晶石锂锰氧化物中氧缺陷对材料电化学性能的影响 总被引:1,自引:0,他引:1
研究了富锂锂锰氧化物中氧缺陷对材料电化学性能的影响。X射线衍射谱表明有氧缺陷的锂锰氧化物仍可保持尖晶石结构,当氧缺陷浓度达到一定程度时,高角度区的衍射峰出现分裂,说明其微观结构发生了变化。充放电实验结果表明氧缺陷使4V区的锂离子嵌脱变成了多步,模拟电池的容量微分曲线有3对清晰的氧化还原峰,低电位的氧化还原峰被—分为二。氧缺陷降低了材料的放电容量,同时引起低电位区的放电容量向更低电位区转移,使电化学性能恶化,锂锰氧化物中氧缺陷对电化学性能的影响对此类材料的合成提供了理论和实践依据。 相似文献
5.
准晶的弹性,塑性与位错 总被引:12,自引:0,他引:12
本文较系统地综述了适合准晶的线弹性理论,准品位错的基本理论和实验鉴定,准晶位错的弹性理论,以及准晶高温塑性形变的微观机制。 相似文献
6.
介绍了用扫描电镜中电子背散射衍射(EBSD)附件所进行的初步研究工作.这些工作表明,2H马氏体的基面由母相的一个{220}P面转变而来,一个自协作马氏体片群内的A、B、C、D4个变体由母相的不同的{110}P面转变而来.用EBSD技术可测出它们之间的取向关系.EBSD技术所提供的结构信息与X射线能谱分析提供的化学成分信息相结合使微区物相鉴定的结果更为可靠.发现Al62.5Cu25Fe12.5合金的铸态主要由λ-Al13Fe4、二十面体准晶和β相3者组成.无间隙钢750℃再结晶后有两类晶粒,其中平坦晶粒具有有利于冷加工性的γ纤维显微织构. 相似文献
7.
GENERALIZATION OF ESHELBY'S METHOD TO THE ANISOTROPIC ELASTICITY THEORY OF DISLOCATIONS IN QUASICRYSTALS
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The general expressions of the elastic fields induced by straight dislocations in quasicrystals have been given according to Eshelby's method which was used to treat the anisotropic elasticity of dislocations in crystals. As an example, the elastic displacement vector, the stress tensor and the elastic energy density of a screw dislocation line lying on the quasiperiodic plane of decagonal quasicrystals are calculated. 相似文献
8.
Experimental Observation on Orientation Relationship between Binary Cd5.7Yb Quasicrystal and its Crystalline Approximant Cd6Yb
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Similarity in the electron diffraction patterns of the Cd5.7 Yb icosahedral quasicrystal and its cubic approximant Cd6 Yb crystal is studied in detail by using transmission electron microscopy. The icosahedral twofold axes are parallel to the cubic (1ττ^2) (τ= 1.618…) or (0 0 1) directions, the icosahedral pseudo-twofold axes are parallel to the cubic (15 21 25) directions, the icosahedral threefold axes are parallel to the cubic 〈1 1 1〉 and the icosahedral fivefold are parallel to the cubic 〈0 1 τ〉 directions. Based on those observations a general stereographic projection is given to illustrate the exact orientation relationship. 相似文献
9.
王仁卉 《武汉大学学报(理学版)》1977,(4)
本文简要评述轻元素(从 Be 到 F)K_α射线质量吸收系数的测定方法,即透射衰减法、等价膜厚法。吸收修正计算法、最有利电压法和全反射法,并将近十余年较有参考价值的测量或内插所得数据收集整理列成附表。 相似文献
10.