Quantitative chemical analysis of vacancy-solute complexes in metallic solid solutions by coincidence Doppler broadening spectroscopy

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Abstract

Low background measurements of 1D momentum spectra of the positron annihilation radiation by the coincidence Doppler broadening (CDB) method are currently used to obtain the quantitative chemical analysis of the environment of vacancy-like defects in supersaturated solid solution of metals. Fractional concentrations are obtained by fitting the CDB spectra with linear combination of reference spectra. Examples regarding Al-based alloys are presented to show the quality of the fitting and the consistency of the CDB analysis with positron lifetime measurements. The appropriate choice of the references is considered a key factor for reducing systematic errors. Nevertheless the method still awaits a theoretical validation. Preliminary first-principles calculations regarding Cu-decorated vacancies in aluminium are presented. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

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