Combined HRTEM and EFTEM Study of Precipitates in Tungsten and Chromium-Containing TiB 2
Combined HRTEM and EFTEM Study of Precipitates in Tungsten and Chromium-Containing TiB 2
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钨和铬 TiB 2 中沉淀物的 HRTEM 和 EFTEM 联合研究
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
Clemens Schmalzried
中科院分区：
文献类型：
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作者：
W. Mader;B. Freitag;K. Kelm;R. Telle;Clemens Schmalzried
采用高分辨透射电镜和能量滤波透射电镜研究了tib2 -WB 2 - crb2体系中两类析出物的结构和化学组成。I型颗粒（w2b5结构）在六角形基体基面上析出，而II型析出物是平行于{1100}棱柱面的薄片状。点阵成像产生金属位置相对于矩阵的位移。利用电子光谱成像（ESI）从所有化学成分的元素图中获得了高横向分辨率的化学成分信息。II型析出物中B、Ti浓度降低，而钨浓度增加，Cr分布均匀。HRTEM结果与元素图结果相结合，可以建立一个基于β-WB结构在tib2 -富基质中共生的结构模型。w0.5 Ti 0.5 B中两个间距为0.38 nm的缺硼层可用于检测ESI的分辨极限。
The structure and chemical composition of two types of precipitates in the system TiB 2 -WB 2 -CrB 2 were studied by means of high-resolution TEM and energy filtering TEM. Type I particles (W 2 B 5 structure) are precipitated at the basal plane of the hexagonal matrix whereas type II precipitates are thin platelets lying parallel to the {1100} prism planes. Lattice imaging yields displacements of the metal positions with respect to the matrix. Information on the chemical composition at high lateral resolution is obtained from elemental maps of all chemical constituents using electron spectroscopic imaging (ESI). The type II precipitates show a decrease in the B and Ti concentration, whereas the tungsten concentration increases and the Cr is homogeneously distributed. The HRTEM results combined with the results of the elemental maps allow to develop a structural model based on the intergrowth of the β-WB structure in the TiB 2 -rich matrix. The two deficient boron layers in W 0.5 Ti 0.5 B with a spacing of 0.38 nm can be used to examine the resolution limit of ESI.