Abstract Alloying nanocrystalline copper (Cu) with immiscible elements, such as tantalum (Ta) and zirconium (Zr), is a promising technique to manipulate grain boundary properties and by this suppress grain growth at elevated temperatures. However, insights on the atomistic origins on the influence of impurity elements on grain boundaries are lacking. In this study, the atomistic effects of Ta and Zr on [111] tilt grain boundaries in Cu are investigated by high resolution scanning transmission electron microscopy techniques. In case of Ta, the formation of spherical, nano-scale precipitates in close vicinity to the grain boundaries is observed, but no sign of segregation. The particles induce a repelling force to migrating boundaries and act as local pinning points. The segregation of Zr is observed to occur either at confined grain boundary steps or homogeneously along the boundaries without steps. In both cases a strong disordering of the defect or grain boundary structure is revealed. Furthermore, at low Zr concentrations it induces structural grain boundary transitions and partial atomic reordering of the grain boundary structural units.

中文翻译：

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钽和锆在铜的复杂 [111] 倾斜晶界处诱导结构转变

摘要 将纳米晶铜 (Cu) 与钽 (Ta) 和锆 (Zr) 等不混溶元素合金化，是一种很有前途的技术，可以控制晶界特性，从而抑制高温下的晶粒生长。然而，缺乏对杂质元素对晶界影响的原子起源的见解。在这项研究中，通过高分辨率扫描透射电子显微镜技术研究了 Ta 和 Zr 对 Cu 中 [111] 倾斜晶界的原子效应。在 Ta 的情况下，观察到靠近晶界的球形纳米级沉淀物的形成，但没有偏析的迹象。粒子对迁移边界产生排斥力并充当局部钉扎点。观察到 Zr 的偏析发生在受限制的晶界台阶处或沿晶界均匀分布，没有台阶。在这两种情况下，都显示出缺陷或晶界结构的严重无序。此外，在低 Zr 浓度下，它会引起结构晶界转变和晶界结构单元的部分原子重新排序。