论文标题
通过原位透射电子显微镜研究CU-AL系统中反应性互化的早期阶段
Investigation of the early stage of reactive interdiffusion in the Cu-Al system by in-situ transmission electron microscopy
论文作者
论文摘要
借助于Situ的传输电子显微镜，在350 {\ textDegree} c和300 {\ textDegree} c中研究了Cu-Al系统中反应性交叉的早期阶段。特别注意找到电子束和样品表面不会显着影响反应的条件。然后，特别强调了快速扩散路径的晶界的影响，以及可能与转化前线相互作用的纳米级颗粒。发现存在瞬态状态，其次是稳态，其中金属间化合物的平均生长速率遵循抛物线定律，表明动力学受到扩散。得益于对纳米级的原位观察结果，也可以跟踪不同阶段之间界面的局部速度。在小于100 nm的长度尺度内表现出强波动，部分归因于纳米级颗粒固定的接口。最后，考虑到热力学和动力学论证，它表明它主要是溶质通量的局部变化和浓度梯度引起的间接效应。
The early stage of the reactive interdiffusion in the Cu-Al system was investigated at 350 {\textdegree}C and 300 {\textdegree}C thanks to in-situ transmission electron microscopy. A special care was given to find conditions where the electron beam and the sample free surface do not affect significantly the reaction. A special emphasis was then given on the influence of grain boundaries that are fast diffusion paths, and on nanoscaled particles that may interact with the transformation front. It was found that there is a transient state followed by a steady state where the mean growth rates of intermetallic compounds follow a parabolic law indicating that the kinetics is diffusion controlled. Thanks to the in-situ observations at the nanoscale, it was also possible to track the local velocity of interfaces between the different phases. Strong fluctuations were exhibited within length scales smaller than 100 nm and they are partly attributed to interface pinning by nanoscaled particles. Last, considering thermodynamic and kinetic arguments, it is shown that it is mainly an indirect effect induced by a local change of solute fluxes and of concentration gradients.
