ABSTRACT

Crystallite-size-dependent lattice expansion of the hcp Ti phase has been observed by X-ray diffraction of polycrystalline Ti thin films. X-ray line profile analysis (XLPA) revealed a systematic reduction of crystallite size in the hcp Ti phase with decreasing film thickness. Increase of specific volume (i.e. volume/atom) of the hcp Ti phase with decreasing crystallite size has confirmed such lattice expansion. The observed lattice expansion has been simulated using an existing theoretical model after appropriately incorporating a crystallite-size-dependent width of the grain boundaries. It is further revealed that decreasing crystallite size and accompanying lattice expansion leads to lattice instability of the hcp Ti phase and eventually to a hcp-fcc phase transformation of elemental Ti in these thin films as reported earlier by the author.

摘要

已经通过多晶 Ti 薄膜的 X 射线衍射观察到 hcp Ti 相的微晶尺寸依赖性晶格膨胀。X 射线线轮廓分析 (XLPA) 揭示了 hcp Ti 相中的微晶尺寸随着膜厚度的降低而系统地减小。随着微晶尺寸的减小，hcp Ti 相的比体积（即体积/原子）的增加证实了这种晶格膨胀。观察到的晶格膨胀已经使用现有的理论模型在适当地结合了晶界的微晶尺寸相关宽度后进行了模拟。进一步表明，减小微晶尺寸和伴随的晶格膨胀导致 hcp Ti 相的晶格不稳定，并最终导致这些薄膜中元素 Ti 的 hcp-fcc 相变，如作者早先报道的那样。