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Low-temperature Diffusion in Crystalline Composition Modulated Films

出版	United States. Department of Energy, 2004
URL	http://books.google.com.hk/books?id=oYDnjwEACAAJ&hl=&source=gbs_api

註釋The diffusivity (D) in alloy systems at low temperatures is determined using composition-modulated structures. An artificial concentration wave is produced by alternating a deposition of the alloy elements. A quantification of the interdiffusivity coefficient is determined by analyzing the decay of the composition fluctuation, that is, the static concentration wave using Khachaturyan's microscopic theory of diffusion. As it's customary to assume that there is a linear relationship between ln D and T over a wide range of temperature (T), the bulk diffusion coefficient represents the long wavelength approximation of the interdiffusivity. The dependency of interdiffusivity on structure is found in general expressions that account for the specific periodicity and growth orientation of the multilayer structure. The kinetics are quantified by analysis of changes in the composition fluctuation with time at temperature through x-ray scattering measurements. In addition to the examination of single-phase crystalline systems as Cu-Ni and Cr-Ti, the theory is now developed to assess diffusion in two-phase layered systems. Specifically, as in Ni-(Cr, Mo) where a face-centered cubic/body centered cubic combination form a pseudo-epitaxial multilayer.