Browsing by Author "Fajardo, Marta"
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Item Synthesis and characterization of Fe0.79Si0.09C 0.12 by mechanical alloying(Physica Status Solidi (C) Current Topics in Solid State Physics, 2007-10-25) Mercado, W. Barona; Ochoa, J. Cuevas; Fajardo, Marta; Pérez Alcázar, Germán Antonio; Sthepa, H. SánchezIron silicon carbide Fe0.79Si0.09C0.12 was prepared by mechanical alloying from elemental powders, with a ball‐to‐powder weight ratio of 20:1. This synthesis was carried out in two stages: in the first stage cementite Fe3C was prepared from elemental iron and carbon powders, the mixed powders were milled for 30 hours. In the second stage Fe0.79Si0.09C0.12 was prepared from cementite Fe3C and Silicon elemental powder as precursors, the samples were milled for 1, 3, 5, 10, 15, 20, 25, 30 and 35 hours. The alloy progress for each milling time was evaluated by X‐ray diffraction (XRD) and 57Fe Mössbauer spectrometry. Nanocrystalline Fe3C powders were obtained from Fe and C, with an average grain size of 15 nm. It was possible to prepare metastable iron silicon carbide such as Fe0.79Si0.09C0.12 and Fe0.81Si0.02C0.17 and their respective hyperfine parameters are reported. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)Item Synthesis and characterization of Fe3AlC0.5 by mechanical alloying(Hyperfine Interactions, 2006-12-07) Mercado, W. Barona; Fajardo, Marta; Pérez Alcázar, Germán Antonio; Sánchez Sthepa, H.Double iron and aluminum carbides were prepared by mechanical alloying from elemental powders, with a ball-to-powder weight ratio 20:1. The samples were milled for 1, 3, 5, 10, 15, 20 and 25 h. The alloy progress for each milling time was evaluated by X-ray diffraction (XRD) and 57Fe Mössbauer spectroscopy. Once the alloy was consolidated two sorts of paramagnetic sites and a magnetic distribution were detected according to the Mössbauer fit. The majority doublet could correspond to Fe3AlC0.5 carbide as X-ray diffraction suggest, and the other could be Fe3AlC0.69; the magnetic distribution corresponding to Fe3Al phase, Fe7C3 and Fe5C2 single carbides. The hyperfine parameters are reported.Item Synthesis and characterization of Fe6W6C by mechanical alloying(Hyperfine Interactions, 2008-05-23) Barona Mercado, W.; Cuevas, J.; Castro, I. Y.; Fajardo, Marta; Pérez Alcázar, Germán Antonio; Sánchez Sthepa, HéctorThe properties of the double iron and tungsten carbide prepared by mechanical alloying technique (MA) from elemental powders are reported. The samples were milled for 1, 3, 5, 10, 15, 20, 25 and 30 h. The alloy progress for each milling time was evaluated by X-ray diffraction (XRD) and 57Fe Mössbauer spectrometry. Once the alloy was consolidated two sorts of paramagnetic sites and a magnetic distribution were detected according to the Mössbauer fitting. The majority doublet could correspond to Fe6W6C ternary carbide as X-ray diffraction suggests, and the other could be Fe3W3C. The hyper fine parameters are reported. Vickers microhardness measurements of 30 h milled sample was conducted at room temperature with a load of 0.245 N for 20 s.