论文标题
Cocrfemnni高熵合金中的晶界扩散：动力学提示朝相分解
Grain boundary diffusion in CoCrFeMnNi high entropy alloy: kinetic hints towards a phase decomposition
论文作者
论文摘要
$^{57} $ co的谷物边界自扩散，$^{51} $ cr，$^{59} $ fe和$^{54} $ mn在一个粗糙的，单相的FCC cocrfemnni高熵合金中，以643至1273〜K-in c-in c-in c-k-kin的范围为643至1273〜K-kin kin kin kin s kin s kin s kin s kin s kin s kin s kin s kin s kin s kin s kin s kin s kin s kin s kin s kin s kin s kiny结果表明，相关隔离因子$ s $和晶界宽度（$δ$）的产物约为0.5 〜nm，温度下的所有元素$ t> 800 $ 〜k。尽管在高于800 k的较高温度下观察到一个短路的贡献，但C型动力学状态（643-703〜K）中的穿透性曲线显示出两个不同的贡献，这些贡献暗示了在这些温度下在高角度边界的一小部分中对相位分解的两个不同贡献。相关显微镜结合透射kikuchi衍射和原子探针断层扫描表现出在高角度晶界的一部分处形成相邻的富含Ni-Mn的较强和富含CR的沉淀。透射电子显微镜表明，此类界面附近的脱位密度增加，这被认为是这种短电路在低温下扩散速率增强的原因。
Grain boundary self-diffusion of $^{57}$Co, $^{51}$Cr, $^{59}$Fe and $^{54}$Mn in a coarse-grained, single-phase fcc CoCrFeMnNi high entropy alloy is measured in a wide temperature range of 643 to 1273~K in both C- and B-type kinetic regimes after Harrison's classification. The results suggest that the product of the pertinent segregation factors, $s$, and the grain boundary width, $δ$, is about 0.5~nm for all elements at temperatures $T>800$~K. Whereas one short-circuit contribution is observed at higher temperatures above 800~K, the penetration profiles in the C-type kinetic regime (643 -- 703~K) reveal two distinct contributions that hint towards a phase decomposition at a fraction of high-angle grain boundaries at these temperatures. A correlative microscopy combining transmission Kikuchi diffraction and atom probe tomography manifests formation of neighbouring Ni-Mn-rich and Cr-rich precipitates at a segment of high angle grain boundaries. Transmission electron microscopy revealed an increased dislocation density in the vicinity of such interfaces which is suggested to be a reason of the enhanced diffusion rates at low temperatures for such short circuits.
