A new method for simple quantification of Laves phases and precipitates in TiCr2 alloys. (June 2019)

• Record Type: Journal Article
• Authors: Coduri, Mauro; Mauri, Stefano; Biffi, Carlo Alberto; Tuissi, Ausonio
• Is Part Of: Intermetallics. Volume 109(2019:Jun.)
• Page Start: 110
• Page End: 122
• Publication Date: 2019-06
• Subjects: Diffraction -- Crystal chemistry -- Laves phases -- TiCr2; Intermetallic compounds -- Metallography -- Periodicals; Metallic glasses -- Periodicals; Composés intermétalliques -- Métallographie -- Périodiques; 669.94
• DOI: 10.1016/j.intermet.2019.03.015
• Languages: English
• ISSNs: 0966-9795

Abstract

Abstract: Laves phases are encountered in many AB2 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. Highlights: A method for simple and fast quantification of Laves phases is provided. It is tested on TiCr2 against laboratory and synchrotron data. Computed phase fractions are consistent within 15% with Rietveld results. Atomic positions are derived for C14 and C36 for different Cr/Ti stoichiometries. Ti and Cr solubilities vary with the Laves phase.