Microstructure evolution and grain size distribution in nanocrystalline FeNbBCu from synchrotron XRD and TEM analysis

TitleMicrostructure evolution and grain size distribution in nanocrystalline FeNbBCu from synchrotron XRD and TEM analysis
Publication TypeJournal Article
Year of Publication2012
AuthorsTorrens-Serra, J, Peral, I, Rodriguez-Viejo, J, Clavaguera-Mora, MT
JournalJournal of Non-Crystalline Solids
Volume358
Start Page107
Issue1
KeywordsCrystallization kinetics, Metallic glasses
Abstract

The microstructure evolution during nanocrystallization of an Fe77Nb7B15Cu1 amorphous alloy is investigated using in situ synchrotron X-ray diffraction (XRD) and transmission electron microscopy (TEM). The microstructure of the nanocrystallized alloy consists in dispersion of bcc-Fe nanocrystals of 4–6 nm of diameter embedded in a stabilized amorphous remaining matrix. The grain size distribution of the nanocrystalline Fe77Nb7B15Cu1 alloy was obtained using three different methodologies: statistical analysis of TEM images, the Warren–Averbach and Langford methods to analyse the XRD patterns and modelling of the diffraction pattern from the Debye equation. A lognormal distribution function has been assumed in all three methods in order to obtain comparable results. A good agreement is found in the calculated average radius and dispersion although some deviations are found with the Langford approach. The microstructure evolution during crystallization was obtained from the XRD patterns during heating (5.0 · 10−3 K s−1) at temperatures between 700 and 900 K. A decrease and prompt saturation of the growth rate is obtained, indicative of the diffusion barrier caused to the overlap between the concentration gradients at the interface of growing grains (soft impingement). A simple model assuming nucleation and initial fast growth of the crystalline grains followed by reduced growth capable of predicting microstructural evolution is presented. The modelling results agree with the experimental observations.

URLhttp://dx.doi.org/10.1016/j.jnoncrysol.2011.09.003
DOI10.1016/j.jnoncrysol.2011.09.003
Short TitleJournal of Non-Crystalline Solids Vol. 358, 1, 1 January 2012, 107-113
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