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

近年来，金属的固态非晶化作为一种不同于一般的蒸汽淬火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。尽管自1983年首次发现以来，已经发现了各种能够实现固态非晶化的合金体系，但对非晶化过程的详细结构研究还没有进行，特别是在原子水平上。本研究采用高分辨电子显微镜和电子衍射技术研究了Co-Zr和Ni-Zr多层薄膜在低温退火非晶化过程中的结构变化。比较了这些结构变化在退火过程中的磁性能变化。所得结果如下：[Co-Zr体系](1)在250℃下退火后，矫顽力降低（100e ~ 60e）。俄歇光谱显示Co和Zr的混合物形成扩散层。(2)扩散层厚度小于20a ^^，在电子衍射和显微镜下均未观察到光晕图案和无定形图像。(3)在高于300℃的温度下，薄膜中Co和Zr晶粒长大。[Ni-Zr体系](1)在350℃以下退火后观察到光晕衍射图样。(2)非晶结构由Co-Zr合金的微晶（20A^^）组成。(3)在该体系中，非晶化和结晶化过程几乎同时进行。在本研究中，没有发现在Cb-Zr和Ni-Zr体系中进行理想的非晶化过程，这可能是由于金属中含有O， C原子抑制了原子的光滑扩散。

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.