Formation of Self-Oriented Nanocrystals in an Amorphous Alloy under Focused-Ion-Beam Irradiation

我们在室温下使用聚焦离子束 (FIB) 辐照在 Ni-P 非晶合金中形成了晶体取向的纳米晶体 (NC)。辐射平面的透射电子显微镜观察揭示了整个辐射区域中NC的形成。通过一系列电子衍射分析，确定所形成的 NC 的结构为 Ni 的面心立方 (fcc)，并确认了所形成的 NC 的以下取向：照射平面法线 ||<111>fcc 和 FIB 方向 ||<110>fcc。形成的NC由两个具有孪生关系的变体组成，孪生平面是照射平面。这些孪生相关晶体具有域状微观结构，平均域尺寸约为 200 nm。非晶合金的弹性各向异性不影响所形成的NCs的晶体学特征。从晶体学和几何学的角度讨论了控制所形成的NC的取向的特征。还研究了 NC 晶体学特征随 Ni-P 非晶合金辐照平面上入射 FIB 角度的变化。当平行于非晶膜照射时，形成纳米晶体，而当垂直于非晶膜照射时，不形成纳米壳。这表明先前形成的纳米晶体可以通过垂直于非晶膜的 FIB 辐射来擦除。我们已经使用这种技术成功地形成了纳米晶体的图案。还尝试通过在 FIB 辐射之前低于结晶温度的预热处理来控制纳米晶体的晶粒尺寸。

We have formed oystallographically oriented nanosized crystals(NCs) in a Ni-P amorphous alloy using focused-ion-beam(FIB) irradiation at room temperature. Transmission electron microscopy observations of the irradiated plane revealed the formation of NCs throughout the irradiated area. From a series of electron diffraction analyses, the structure of the formed NCs was determined to be face-centered cubic(fcc) of Ni and the following orientation of the formed NCs was confirmed : Irradiated plane normal ||<111>fcc, and FIB direction ||<110>fcc. The formed NCs consisted of two variants which have a twin relation, the twinning plane being the irradiated plane. These twin related crystals have a domain-like microstructure with an average domain size of approximately 200 nm. The elastic anisotropy of the amorphous alloy does not affect the crystallographic features of the formed NCs. The features which control the orientation of the formed NCs are discussed from crystallographic and geometrical points of view. Changes in the crystallographic features of the NCs as a function of the incident FIB angle on the irradiated plane of Ni-P amorphous alloy have been also investigated. When irradiating parallel to the amorphous film, nanocrystals were formed, whereas nanocrustals were not formed when irradiating perpendicular to the amorphous film. This suggests that nancrystals, which had been formed previously, can be erased by FIB irradiation from perpendicular to the amorphous film. We have succeeded the patterning of nanocrystals using this technique. The possibility of grain size control of nanocrystals is also attempted by pre-heat treatments below crystallization temperature before FIB irradiation.