High Resolution Electron Microscopic Observation of Solid-State Amorphization Process in Multi-Layered Co-Zr Films

近年来，金属固态反应非晶化作为一种不同于通常的蒸气或液体淬火方法的扩散控制非晶化方法，受到了广泛的关注。虽然自1983年首次发现以来，已经发现了能够实现固态非晶化的各种合金系统，但是还没有特别在原子水平上对非晶化过程进行详细的结构研究。在这项研究中，多层Co-Zr和Ni-Zr薄膜的结构变化在非晶化过程中的低温退火进行了研究，通过高分辨电子显微镜和电子衍射。这些结构的变化进行了比较退火的磁性变化。结果表明：（1）Co-Zr系合金在250 ℃退火后，磁性下降（100 e ~ 60 e）。俄歇能谱表明，形成的扩散层与Co和Zr的混合物。（2）扩散层厚度小于20埃，在电子衍射和显微镜下没有观察到晕圈图案和非晶图像。（3）当退火温度高于300 ℃时，薄膜中Co和Zr的晶粒长大。[Ni-Zr系]（1）在350 ℃以下退火后观察到晕衍射花样。（2）Co-Zr合金的非晶组织由微晶（20埃）组成。(3)In该系统的非晶化和结晶化过程几乎同时进行。在本研究中，没有发现理想的非晶化过程中进行的Cb-Zr和Ni-Zr系统，这可能是由于在金属中的O，C原子的包含，以抑制平稳的原子扩散。

In recent years, amorphization of metals by solid state reaction process has been paid much attention as a diffusion-controlled amorphization method different from usual vapor or liquid-quenching methods. Although various alloy systems which enable the solid-state amorphization have been discovered since the first discovery in 1983, detailed structural investigations in the amorphization process have not been made especially at an atomic level. In this study, structural changes of multi-layered Co-Zr and also Ni-Zr thin films in the amorphization process on low temperature annealing have been investigated by high resolution electron microscopy and electron diffraction. These structural changes were compared with magnetic property changes on annealing. The obtained results are as follows; [Co-Zr system] (1)Magnetic coercivity decrease(100e to 60e) occurred after annealing at 250ﾟC. Auger spectroscopy showed a formation of diffusional layer with a mixture of Co and Zr. (2)The diffusional layer was found to be thinner than 20 A^^ﾟ and no halo pattern nor amorphous image were observed in electron diffraction and microscopy. (3)The films showed a grain growth of Co and Zr on annealing at temperature higher than 300ﾟC. [Ni-Zr system] (1)Halo diffraction patterns were observed after annealing at temperatures below 350ﾟC.(2)The amorphous structure was found to be composed of microcrystalline grains( 20A^^ﾟ) of Co-Zr alloy. (3)In this system amorphization and crystallization process proceed almost at the same time. In this study, no ideal amorphization process was found to proceed in Cb-Zr and Ni-Zr systems, which is probably due to an inclusion of O, C atoms in metals to inhibit a smooth atomic diffusion.