Electrochemical properties of nanocrystalline Mg_2Ni-type alloys prepared by mechanical alloying

摘要

The electrochemical hydrogen charge/discharge properties of nanocrystalline and nanocrystalline/amorphous Mg_2Ni-based alloys with different microstructure (e.g. different average nanocrystals size, different amount of the amorphous phase), prepared by mechanical alloying and mechanical alloying with subsequent controlled annealing, were studied. It was found that larger amount of amorphous phase improved the capacity of the alloy. Alloys with similar nanograin size, but prepared in a different way showed different electrochemical charge/discharge behaviour as well. The as-milled nanocrystalline alloy (7-10 nm), characterized by higher concentration of defects and some amorphous fraction, reveals slightly higher hydrogen capacity than the completely nanocrystalline material (7-10 nm), produced by milling and subsequent annealing. The nanocrystal size reduction in fully crystalline alloys results in noticeable increase of the hydrogen capacity as well.