Search

A method for the retrieval of concentration spectra of crystalline mixtures from x-ray diffraction profiles is described. Both spectra are associated with an integral equation which can be simplified to yield a set of linear equations. Solutions are readily obtained by triangular decomposition since the equations are typically described by band matrices. The method has been tested with simulated diffraction profiles to allow for a variety of options concerning the concentration spectra. The procedure is well suited for binary alloys containing crystals of different structure and lattice parameters. The time consumption of the calculations is significantly reduced as compared to hitherto available methods.

On the basis of hypothetical thin film couples in which a grain-boundary supported diffusion process is simulated, it is shown that the concentration spectrum may contain maxima which would not occur if the process were governed by lattice diffusion only. As such maxima consequently appear in the diffraction pattern, real diffraction profiles of interdiffusion layers must be interpreted carefully, keeping in mind that diffraction peaks need not necessarily be associated with a particular phase. The thin-film diffusion system Au-Cu is chosen as an example to demonstrate experimentally the generation of diffraction maxima which must not be attributed to phase formation.