2Mg-Fe Alloy Processed by Hot Extrusion: Influence of Particle Size and Extrusion Reduction Ratio on Hydrogenation Properties

Abstract:

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Samples of a 2Mg-Fe (at.%) mixture were produced by high energy ball-milling (HEBM) with ball to powder ratio = 20:1, in an argon gas atmosphere, in 190 ml vials (sample-1) to produce powders and in 300 ml vials (sample-2) to produce plates. Both samples were cold-pressed into preforms. The preforms were then extruded at 300°C at a ram speed of 1mm/min., with the following extrusion ratios: sample-1 at 3/1 to ensure porosity and sample-2 at 5/1 to increase the adhesion of the plates. The resulting bulks from samples 1 and 2 were hydrogenated for 24h in a reactor under 15 bar of H2 to produce the Mg2FeH6 complex hydride, and at 11 bar of H2 to produce both the complex hydride and MgH2 hydride. In addition, sample-1 was severely temperature-hydrogen cycled to verify its microstructural stability and the influence of grain size on the sorption properties. XRD patterns showed Mg(hc), Fe(ccc) and Mg2FeH6 in both samples, and sample-2 also contained MgH2 and MgO (attributed to processing contamination). DSC results demonstrated that the initial desorption temperature of sample-1 was lower than that of sample-2. However, sample-2 showed faster desorption kinetics, presenting a desorption peak about 73°C below that of sample-1. This could be attributed to the activation/catalyst effect of the MgH2 hydride. The improvement in sorption properties was attributed mainly to porosity and to the type of employed catalysts.

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Periodical:

Edited by:

J. Federico Chávez Alcalá, Alejandro Cruz Ramírez and Ma. de los Ángeles Hernández Pérez

Pages:

3-9

DOI:

10.4028/www.scientific.net/MSF.691.3

Citation:

G. F. De Lima et al., "2Mg-Fe Alloy Processed by Hot Extrusion: Influence of Particle Size and Extrusion Reduction Ratio on Hydrogenation Properties", Materials Science Forum, Vol. 691, pp. 3-9, 2011

Online since:

June 2011

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$35.00

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