Laves phases are encountered in many AB 2 intermetallic compounds. They consist of one cubic (C15) and two hexagonal (C14 and C36) phases. All of them have characteristic cavities, which favour the hosting external molecules, leading to potential application for hydrogen storage. From a crystallographic point of view, Laves phases consist of different stackings of the same units. Hence, many Bragg reflections of Laves phases overlap and the accurate phase quantification is hindered through conventional methods. Here we propose a simple method, based on the relative intensities of three diffraction peaks, to perform a first quantification of Laves phases. No crystallographic background is required. The method is tested using laboratory diffractometer on a set of TiCr samples produced with different compositions and thermal treatments. Synchrotron radiation data were used for comparison and to assess lattice parameters and atomic structure as a function of Cr/Ti. Considering the relative phase fractions computed by Rietveld refinements as a reference, ∼90% of the phase fractions computed by FQA differ by less than 15%. Precipitates were identified and quantified combining X-ray diffraction and electron microscopy.
A new method for simple quantification of Laves phases and precipitates in TiCr 2 alloys
Coduri M.
;
2019-01-01
Abstract
Laves phases are encountered in many AB 2 intermetallic compounds. They consist of one cubic (C15) and two hexagonal (C14 and C36) phases. All of them have characteristic cavities, which favour the hosting external molecules, leading to potential application for hydrogen storage. From a crystallographic point of view, Laves phases consist of different stackings of the same units. Hence, many Bragg reflections of Laves phases overlap and the accurate phase quantification is hindered through conventional methods. Here we propose a simple method, based on the relative intensities of three diffraction peaks, to perform a first quantification of Laves phases. No crystallographic background is required. The method is tested using laboratory diffractometer on a set of TiCr samples produced with different compositions and thermal treatments. Synchrotron radiation data were used for comparison and to assess lattice parameters and atomic structure as a function of Cr/Ti. Considering the relative phase fractions computed by Rietveld refinements as a reference, ∼90% of the phase fractions computed by FQA differ by less than 15%. Precipitates were identified and quantified combining X-ray diffraction and electron microscopy.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
