Grain boundary diffusion of Cr in a near Ni bicrystal is measured over a temperature interval between 503 K and 1203 K using the radiotracer technique. The grain boundary diffusion coefficients, , and the triple products, , are determined in the C- and B-type kinetics regimes, respectively, with being the segregation factor and the grain boundary width. Opposite to expectations, two distinct contributions to short-circuit diffusion along the nominally single interface are distinguished and related to the existence of two macroscopic facets with distinct grain boundary inclinations and, as a result, distinct structures. The experimental results indicate that the segregation factor of Cr in Ni is about unity, which is fully supported by calculations. Using classical atomistic simulations, Ni grain boundary self-diffusion coefficients are calculated for the symmetric and asymmetric facets. The computational simulations reveal accelerated self-diffusion kinetics along the asymmetric facet, attributing this phenomenon to the presence of disconnection-like defects. This elucidates the experimentally observed diffusion dynamics of chromium atoms, thereby corroborating the heterogeneous mechanisms governing atomic migration across distinct facets.

中文翻译：

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Ni[公式省略]双晶中Cr的晶界扩散和偏析：解码晶界缺陷的作用


使用放射性示踪剂技术在 503 K 和 1203 K 之间的温度区间测量 Cr 在近 Ni 双晶中的晶界扩散。晶界扩散系数 和三重乘积 分别在 C 型和 B 型动力学体系中确定，其中 为偏析因子和晶界宽度。与预期相反，沿着名义上的单一界面对短路扩散的两种不同贡献是有区别的，并且与具有不同晶界倾角的两个宏观面的存在有关，因此具有不同的结构。实验结果表明，Ni中Cr的偏析因子约为1，这得到了计算的充分支持。使用经典原子模拟，计算对称和非对称面的镍晶界自扩散系数。计算模拟揭示了沿着不对称面的加速自扩散动力学，将这种现象归因于类似断开的缺陷的存在。这阐明了实验观察到的铬原子扩散动力学，从而证实了控制原子跨不同面迁移的异质机制。