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Evolution microstructurale et comportement mécanique des composites à base de MgH₂ au cours des cycles d'hydruration

Abstract : The last decade the magnesium hydride stood out as the most attractive candidatefor solid storage of hydrogen at large scale. The main subject of this study is thephenomenon of irreversible swelling of the composites based on magnesium hydride, duringthe hydriding/dehydriding cycles as well as the evolution of their mechanical properties.In-situ dilatometry measurements and the microstructural characterizations (SEM,granulometry) were performed on magnesium hydride samples co-milled with vanadium orTi-V-Cr additive. The results reveal that the coalescence of nanometric particles tends tocreate large agglomerates, which induce an increase in porosity, and explain the progressiveswelling of composites.The nanoindentation tests performed on compacted pellets show an enhancement ofabout 30 % of the Young modulus after 10 cycles. From the Vickers hardness measured oncompacted powders, the hardness of a highly densified magnesium hydride wasextrapolated to 0.58 GPa, which shows that the magnesium hydride is harder thanmagnesium.
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  • HAL Id : tel-01686419, version 1

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Simeon Nachev. Evolution microstructurale et comportement mécanique des composites à base de MgH₂ au cours des cycles d'hydruration. Mécanique des matériaux [physics.class-ph]. Université Grenoble Alpes, 2015. Français. ⟨NNT : 2015GREAY077⟩. ⟨tel-01686419⟩

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