纳米团聚生长的多重分形谱

采用小角x射线散射（SAXS）方法，对两类具有代表性的纳米团聚的生长分形进行了表征.一 类为用化学方法 (水合肼溶液还原法) 制备的纳米金属Ni粉；另一类通过物理方法(纳米晶 化处理)，由非晶基体相中生长纳米晶相、形成非晶/纳米晶双相结构的Finemet (Fe_{73 .5} Cu₁Nb₃Si_13.5B₉) 合金.上述两 类材料的纳米团聚在生长过程中都存在 明显元素扩散迁移，形成在1—100 nm范围内的元素分布非均匀区域.这些元素分布的非均匀 区域具有多重质量生长分形特征，其尺度大小和分布方式对最终的材料的物理性能至关重要 .SAXS方法是表征这类具有分形生长特征的纳米团聚微观结构信息的强有力手段.从方法论的 角度详述了从SAXS测量到获得多重分形谱的处理过程，这一实验研究分析手段对于定量考察 纳米微结构形貌的生长机理和性能的其他研究课题有一定的帮助作用. 关键词： 纳米材料 分形生长 小角x射线散射 磁性材料

Multifractal spectra of growing clusters in nanoscale characterized by small angle x-ray scattering

Small angle x-ray scattering (SAXS) method was adopted to investigate the characteristics of growth fractal of two sorts of typical nanoscaled clusters, i.e. g rowing in both ultrafine Ni powders synthesized by chemical reaction and Finemet (Fe_73.5Cu₁Nb₃Si_13.5B₉) a morphous ribbon by physical crystal lization annealing. The SAXS measurement discloses definitely the existence of d istinct mass multifractal patterns within ultrafine Ni granules and crystallizin g Finemet ribbon. The multifractal spectra of the clusters mentioned above sugge st the occurrence of inhomogeneous distribution of constituent elements and grow th fractal during the formation of those nanoscale clusters. The multifractal sp ectra of ultrafine Ni powders prepared using a variety of procedures take on an obvious difference in shape, indicating the substantial influence of preparation process on diffusion of constituent elements and the growth mechanism of cluste rs. The crystallization annealing processes, however, affect the multifractal sp ectra of Finemet alloy slightly.