Structural stability and dehydrogenation of (MgH2 + Al, Nb) powder mixtures during mechanical alloying

Shang, Congxiao, Bououdina, Mohamed and Guo, Zheng Xiao (2003) Structural stability and dehydrogenation of (MgH2 + Al, Nb) powder mixtures during mechanical alloying. Materials Transactions, 44 (11). pp. 2356-2362. ISSN 1347-5320

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Abstract

High-energy ball milling of MgH2 with appropriate alloying elements is reported to improve the hydrogenation kinetics of MgH2 but the relevant information on dehydrogenation is scarce. Here, a systematic study was carried out to clarify the effects of two key alloying elements, Nb and Al, on the microstructure and the dehydrogenation behaviour of the MgH2. Intensive mechanical alloying was carried out to synthesise (MgH2 + M) powder mixtures (M=Nb, Al). XRD Rietveld analysis revealed the formation of a new bcc phase in the (MgH2+Nb) mixture and a (Al, Mg) solid solution in the (MgH2+Al) mixture. The amount of the newly formed phase in each case increased with milling time, while the level of Nb or Al decreases. SEM analysis of the milled powders showed the existence of nano-particles within 20 hours of milling. Thermogravimetry (TG) results showed that the mechanically alloyed (MgH2+Nb) mixture released about 3.9 mass% H2 and the milled (MgH2 + Al) about 5.4 mass% H2 at 300°C within 10 minutes, compared with only 1.5 mass% of the milled MgH2 powder and 1.0 mass% of the as-received MgH2 under the same conditions.

Item Type:	Article
Faculty \ School:	Faculty of Science > School of Environmental Sciences
UEA Research Groups:	Faculty of Science > Research Groups > Geosciences
Depositing User:	Rachel Snow
Date Deposited:	16 Mar 2011 14:33
Last Modified:	12 Jan 2024 01:24
URI:	https://ueaeprints.uea.ac.uk/id/eprint/26403
DOI:	10.2320/matertrans.44.2356

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