The addition of Al to Mg has been indicated as a suitable way to destabilise the hydride phase, in order to bring the absorption and desorption reactions close to reasonable temperatures and pressure values for hydrogen storage. Rapid solidification is known to refine the microstructure of Mg-Al alloys and it might improve the H(2) absorption/desorption kinetics. In this paper, the interaction of H(2) with rapidly solidified Mg-Al alloys have been studied for three different composition: Mg(38.5)Al(61.5), Mg(69)Al(31) and Mg(72)Al(28). For Mg(72)Al(28), no significant changes in the microstructure have been obtained by rapid solidification. In Mg(69)Al(31), a significant grain refinement has been observed, whereas, for Mg(38.5)Al(61.5), the formation of a metastable hexagonal phase has been found. In all cases, a disproportionation reaction has been observed after H(2) absorption, leading to MgH(2). After heating up to 430 degrees C the hydrogenated samples, a main desorption reaction from MgH(2) has been observed, which brings again to the starting phases. Experimental results have been discussed on the basis of a thermodynamic assessment of the Mg-Al-H system.
Hydrogen absorption and desorption in rapidly solidified Mg- Al alloys / J., Urgnani; M., Di Chio; M., Palumbo; M., Feuerbacher; J. F., Fernandez; Leardini, Fabrice; M., Baricco. - In: JOURNAL OF PHYSICS. CONFERENCE SERIES. - ISSN 1742-6596. - ELETTRONICO. - 144:(2009), p. 012016. (Intervento presentato al convegno 13TH INTERNATIONAL CONFERENCE ON RAPIDLY QUENCHED AND METASTABLE MATERIALS tenutosi a Dresden, GERMANY nel AUG 24-29, 2008) [10.1088/1742-6596/144/1/012016].
Hydrogen absorption and desorption in rapidly solidified Mg- Al alloys
LEARDINI, FABRICE;
2009
Abstract
The addition of Al to Mg has been indicated as a suitable way to destabilise the hydride phase, in order to bring the absorption and desorption reactions close to reasonable temperatures and pressure values for hydrogen storage. Rapid solidification is known to refine the microstructure of Mg-Al alloys and it might improve the H(2) absorption/desorption kinetics. In this paper, the interaction of H(2) with rapidly solidified Mg-Al alloys have been studied for three different composition: Mg(38.5)Al(61.5), Mg(69)Al(31) and Mg(72)Al(28). For Mg(72)Al(28), no significant changes in the microstructure have been obtained by rapid solidification. In Mg(69)Al(31), a significant grain refinement has been observed, whereas, for Mg(38.5)Al(61.5), the formation of a metastable hexagonal phase has been found. In all cases, a disproportionation reaction has been observed after H(2) absorption, leading to MgH(2). After heating up to 430 degrees C the hydrogenated samples, a main desorption reaction from MgH(2) has been observed, which brings again to the starting phases. Experimental results have been discussed on the basis of a thermodynamic assessment of the Mg-Al-H system.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
