HRTEM study of defects in twin boundaries of ultra-fine grained copper
HRTEM study of defects in twin boundaries of ultra-fine grained copper
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DOI：
10.1080/14786430601021611
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发表时间：
2007-04-01
影响因子：
1.6
通讯作者：
Hytch, M. J.
中科院分区：
文献类型：
--
作者：
Sennour, M.;Lartigue-Korinek, S.;Hytch, M. J.
使用高分辨率透射电子显微镜 (HRTEM) 和几何相分析 (GPA) 研究了粉末冶金制备的超细晶粒 (UFG) 铜中的孪晶界 (TB)。对机械变形（压缩 40%）之前和之后的样本进行了分析，并重点研究了 TB 缺陷。处理后的样本中的孪晶边界主要与完美的 Sigma 3 重合方向不一致。它们呈现出具有相干{111}面和不相干{112}面的多面结构。后者具有 9R 结构，{111}/{112} 连接与 Frank 型固位位错 (b = (a/3)<111>) 相关。还存在具有 Burgers 矢量类型的肖克利滑动位错。这种微观结构是根据晶格位错（60 度型）在室温下的吸收和分解来解释的。机械变形后，通过统计分析观察并量化位错处孪晶的富集以及阶梯密度和高度的降低。根据这些观察结果讨论了 UFG 铜的变形机制。
Twin boundaries (TBs) in ultra-fine grained (UFG) copper prepared by powder metallurgy were investigated using high-resolution transmission electron microscopy (HRTEM) and geometric phase analysis (GPA). Specimens were analyzed both before and after mechanical deformation (compression of 40%) and emphasis placed on the study of TB defects. Twin boundaries in the as-processed specimens are mainly disoriented from the perfect Sigma 3 coincidence. They present a faceted structure with coherent {111} and incoherent {112} facets. The latter have a 9R structure and the {111}/{112} junctions are associated with sessile dislocations of Frank type (b = (a/3)< 111 >). Shockley glissile dislocations with Burgers vector of type are also present. This microstructure is interpreted in terms of the absorption and decomposition at room temperature of lattice dislocations (60 degrees type). After mechanical deformation, an enrichment of twins at dislocations and a decrease of step density and height is observed and quantified by statistical analysis. Deformation mechanisms of UFG copper are discussed in light of these observations.