Hydrogen storage properties of 2 Mg–Fe mixtures processed by hot extrusion: Effect of ram speeds

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Correlation between hydrogen storage properties and textures induced in magnesium through ECAP and cold rolling

It is feasible to obtain a significant enhancement of the hydrogen storage capability in magnesium by selecting an appropriate sequence of mechanical processing. the Mg metal may be produced with different textures which will then give significant differences in the absorption/desorption kinetics and in the incubation times for hydrogenation. Using processing by equal-channel angular pressing (ECAP), different textures may be produced by changing both the numbers of passes through the ECAP die and the ram speed. Significant grain refinement is easily avoided by using commercial coarse-grained magnesium as the starting material. the use of cold rolling after ECAP further increases the preferential texture for hydrogenation. the results show that the hydriding properties are enhanced with a (002) texture where the improved kinetics lie mainly in the initial stages of hydrogenation. An incubation time is associated with the presence of a (101) texture and this is probably due to the magnesium oxide stability in this direction. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)European Research CouncilUniv Fed Sao Carlos, Dept Mat Engn, BR-13565905 Sao Carlos, SP, BrazilUJF, INPG, CNRS, SiMap Lab,UMR 5266, F-38402 St Martin Dheres, FranceUJF, INPG, CNRS, LEPMI,UMR 5279, F-38402 St Martin Dheres, FranceUniversidade Federal de São Paulo, BR-12231280 Sao Jose Dos Campos, SP, BrazilUniv So Calif, Dept Aerosp & Mech Engn, Los Angeles, CA 90089 USAUniv So Calif, Dept Mat Sci, Los Angeles, CA 90089 USAUniv Southampton, Fac Engn & Environm, Mat Res Grp, Southampton SO17 1BJ, Hants, EnglandUJF, INPG, CNRS, LEPMI,UMR 5279, F-38402 St Martin Dheres, FranceUniversidade Federal de São Paulo, BR-12231280 Sao Jose Dos Campos, SP, BrazilFAPESP: 2011/51245-8CNPq: 237345/2012-9 PDE (CsF)European Research Council: 267464-SPDMETALSWeb of Scienc

Effect of cold rolling on the structure and hydrogen properties of AZ91 and AM60D magnesium alloys subjected to ECAP

It is attainable obtaining an appreciable amelioration of the hydrogen storage ability in magnesium by settling on a suitable sequence of mechanical processing. It is plausible to predict that a reduction in grain size into nanocrystalline dimensions may predispose to a substantial improvement in the diffusion and thermo-dynamical properties in magnesium hydride. This may be realized by Severe Plastic Deformation (SPD). The use of cold rolling after ECAP, a kind of SPD, considerably increases the preferential texture for hydrogenation. In this research, the association of ECAP and cold rolling was used to process commercial AM60D and AZ91 extruded alloys in order to evaluate their use as hydrogen storage materials. The ECAP was conducted under distinct conditions of numbers of passes in order to attain different grain sizes. After ECAP, both materials were cold rolled with the same number of passes for comparison of hydrogenation absorption. Hydriding properties are enhanced by (0001) texture, which improved kinetics mainly in the initial stages of hydrogenation and was effective even with unfavorable grain size. However, the presence of precipitates limits the storing capacity. Finally, it was demonstrated that optimum sorption properties may be acquired with the synergy between fine grains and the best texture