The invention belongs to the field of the preparation of rare-earth alloys and particularly relates to an electrolytic eutectoid alloying method for a rare-earth-
magnesium-
nickel-based
hydrogen storage
alloy. The electrolytic eutectoid alloying method for the rare-earth-
magnesium-
nickel-based
hydrogen storage
alloy, disclosed by the invention, comprises the steps: adopting a circular or square
graphite electrolysis tank, and placing an undertake
crucible at the bottom of the
electrolysis tank; carrying out joint electrochemical
precipitation on cathodes RE (Rare-Earth) and Mg (
magnesium) in a manner of taking a
metallic nickel (Ni) rod as a
cathode, taking
fluoride fused salts, such as REF3-LiF-MgF2-BaF2, as an
electrolyte and taking a mixture of RE2O3 and MgO as a
raw material, alloying with
nickel which serves as a
cathode, so as to obtain an RE-Mg-Ni
alloy, and sinking into the undertake
crucible, thereby obtaining the rare-earth-magnesium-nickel-based
hydrogen storage alloy. The method has the beneficial effects that the problem that magnesium is subjected to volatilization and oxidation during the
smelting of the rare-earth-magnesium-nickel-based
hydrogen storage alloy is effectively solved, the rare-earth-magnesium-nickel-based
hydrogen storage alloy is adjustable and controllable in ingredients and can be obtained stably, the
electrolysis work is continuous, the production process is safe, the process flow is short, and the cost is low.