Microstructure and Corrosion Resistance of LaNi5-xMgx Alloys

This study analysed the corrosion parameters of LaNi5-xMgx hydrogen-absorbing alloys depending on the degree of replacement of nickel with magnesium and the exposure time of samples in a strongly alkaline solution. The microstructure and composition of the alloys were analysed using SEM and EDS, respectively. A correlation was observed between the corrosion rate and the magnesium content in the alloy and the exposure time of the investigated materials in the corrosive solution. The obtained research results showed that the LaNi5 phase, rich in Mg, corroded easily, and the presence of Mg in LaNi5-xMgx alloys became beneficial only for longer exposure times of samples in an alkaline solution. The corrosion layer formed during the contact of the magnesium alloys with the electrolyte promoted faster H-2 evolution compared to the non-magnesium-substituted alloy.