HRTEM investigation of diffusion in metallic-glass multilayer films

Here we present a data set on our research of diffusion in metallic glass multilayers. In the present data set we combined raw data from nanoindentation, SEM and TEM experiments.
Lack of plasticity is one of the main disadvantages of metallic glasses. One of the solutions to this problem can be composite materials. Diffusion bonding is promising for composite fabrication. In the present work the diffusion process in glassy multilayer films was investigated. A combination of advanced TEM methods and precision sputtering techniques allows visualization and study of diffusion in amorphous metallic layers with high resolution. Multilayered films were obtained by RF sputter deposition of Zr-Cu and Zr-Pd. The multilayers were annealed under a high vacuum (10‒5 Pa) for 1 and 5 hours at 400oC, i.e. well below the crystallization temperatures but very close to the glass-transition temperatures of both types of glassy layer. The structural evolution in the deposited films was investigated by high-resolution transmission electron microscopy. It was observed that despite the big differences in the atomic mass and size, Pd and Cu have similar diffusion coefficients. Surprisingly, 1 hour of annealing results in formation of metastable copper nanocrystals in the Zr-Cu layers which, however, disappear after 5 h of annealing. This effect may be connected with nanovoid formation under a complex stress state evolving upon annealing, and is related to the exceptionally slow relaxation of the glassy layers sealed with a Ta overlayer.

本数据集汇集了我们关于金属玻璃多层扩散的研究成果。在本数据集中，我们融合了纳米压痕、扫描电子显微镜（SEM）和透射电子显微镜（TEM）实验的原始数据。金属玻璃缺乏延展性是其主要缺陷之一。针对这一问题的解决方案之一是复合材料。扩散连接在复合材料的制造中具有广阔的前景。在本次研究中，我们探讨了玻璃多层薄膜中的扩散过程。通过结合先进的TEM方法和精密溅射技术，我们得以以高分辨率可视化并研究非晶态金属层的扩散。通过射频溅射沉积获得了Zr-Cu和Zr-Pd多层薄膜。这些多层薄膜在10‒5 Pa的高真空条件下于400°C下退火1小时和5小时，即远低于结晶温度，但非常接近两种玻璃层玻璃化转变温度。我们通过高分辨率透射电子显微镜研究了沉积薄膜的结构演化。观察结果显示，尽管钯和铜的原子质量和尺寸存在显著差异，但它们的扩散系数却相似。令人惊讶的是，1小时的退火处理在Zr-Cu层中形成了亚稳态的铜纳米晶体，然而，这种效果在5小时的退火后消失。这一现象可能与退火过程中复杂应力状态下纳米空位的形成有关，并且与使用钽层封装的玻璃层异常缓慢的弛豫相关。