DECOMPOSITION RE-FORMATION REACTIONS UNDER H-2 OF INTERMETALLICS BASED ON LANI5

Hydrogen decomposition-re-formation processes of LaNi5-type intermetal lics are known to produce activated homogeneous materials with variabl e microstructures (e.g. of relevance to aspects of an alternative hydr ogen economy such as battery or hydrogen storage applications). An exa mple is LaNi5, H-2 --> LaNiH2, Ni --> LaNi5. The route and thermodynam ics of these processes have been investigated on La(NiAl)(5) and La(Ni Co)(5)-based materials. It was found that for intermetallics with high exothermicity (e.g. LaNi5 and (NiAl)(5)), relatively forcing conditio ns have to be used in the decomposition process. Other compounds such as La(NiCo)(5) readily decomposed and re-formed near 500 degrees C.