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.
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J. Chakraborty
Dr. J. Chakraborty is the senior principal scientist at the Materials engineering division, National metallurgical laboratory under the ‘Council of scientific & industrial research’, India. He obtained his Ph.D degree from the ‘Max-Planck Institute for Metals Research’, Stuttgart, Germany in 2005. His research interests are diffusion and phase transformation in metallic thin films and nanomaterials, X-ray diffraction analysis of phase transformation, microstructure and residual stresses in thin films and bulk materials. He has more than twenty years of research experience including industrial R&D and academia.