The effect of nanocrystalline formation on the hydrogen storage properties of AB3-base Ml–Mg–Ni multi-phase alloys

In the present investigation, high energy ball milling and annealing were used to manipulate the grain size of AB3 based Ml0.7Mg0.3Ni3.2 multi-phase alloys (here Ml denotes La-rich mish metal). X-ray diffraction, transmission electron microscopy and pressure–composition–isothermal measurements were used to characterize the microstructure and hydrogen storage properties of the alloys after different milling and annealing treatments. It has been found that hydrogen storage capacity decreases with decreasing of grain size caused by milling. However, the hydrogen storage capacity of the milled alloy recovers gradually to the value of the as-cast state after annealing in a temperature range of 973–1173 K. The effect of grain size on hydrogen storage property has been discussed based on the interaction of hydrogen with the inter- and intra-grain region of nanocrystalline alloys.