Two types of intermetallic compounds, LaNi4M with M = Mn, Co, Cu and Al and polysubstituted alloys Mm(NiAlMnCo)5 with Mm = Mischmetal were synthesized by mechanical alloying. In most cases, 10 h grinding was sufficient to obtain single phase alloys with crystallites of about 6 nm and particles ranging between 5 and 80 mm in diameter. The polysubstituted MmNi3.6Al0.35Mn0.25Co0.8 alloys, once removed from the grinding container, were found to present an electrochemical capacity of 159 mA h/g. Such a capacity was increased to 216.3, 241.7 and 273.5 mA h/g by a post-anneal step under vacuum to temperatures of 673, 873 and 1073 K, respectively. The various electrochemical capacity depends on both surface states and internal strains in the sample so that the heat treatments release these strains and enhance the capacity
