HAADF study of the relationship between intergranular defect structure and yttrium segregation in an alumina grain boundary
HAADF study of the relationship between intergranular defect structure and yttrium segregation in an alumina grain boundary
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DOI：
10.1016/j.actamat.2011.02.025
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发表时间：
2011-05-01
期刊：
影响因子：
9.4
通讯作者：
Colliex, Christian
中科院分区：
文献类型：
--
作者：
Lartigue-Korinek, Sylvie;Bouchet, Daniele;Colliex, Christian
为了理解钇在氧化铝蠕变中的有益作用，使用扫描电子显微镜中的Z对比度高角度环形暗场（HAADF）成像来揭示氧化铝中菱形孪晶中的晶间位错（即断开）的核心中钇偏析的分布。缺陷容纳从孪晶取向的倾斜偏差，并呈现大的台阶高度。在未掺杂的双晶体位错出现最经常解离成局部界定晶界（GB）段交替结构。在掺杂的双晶中，强烈的钇偏析出现沿着的步骤，延伸到几个平面垂直于孪晶面。钇被分离到缺陷的有缺陷的部分。此外，它似乎偏聚到部分断开的核心。它不是简单地采用氧化铝结构，而是形成接近YAlO3化合物的新结构。在GB位错核心的有序化合物的形成强烈支持的假设，降低蠕变速率的结果从GB滑动过程中的位错迁移率降低。(C)2011 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
In order to understand the beneficial role of yttrium in the creep of alumina, Z-contrast high-angle annular dark field (HAADF) imaging in a scanning electron microscope was used to reveal the distribution of yttrium segregation in the core of intergranular dislocations, namely disconnections, in a rhombohedral twin in alumina. The defects accommodate the tilt deviation from twin orientation and present a large step height. In the undoped bicrystal the dislocations appear most often dissociated into partials that delimit grain boundary (GB) segments with alternating structure. In the doped bicrystal, a strong yttrium segregation appears along the step, extending over several planes normal to the twin plane. Yttrium is segregated to the faulted part of the defect. Moreover, it appears segregated to the partial disconnection cores. It does not simply adopt the alumina structure but forms a new structure close to a YAlO3 compound. The formation of an ordered compound at the GB dislocation core strongly supports the hypothesis that a reduced creep rate results from a decrease in dislocation mobility during GB sliding. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.