Enhanced hydrogen absorption kinetics by introducing fine eutectic and long-period stacking ordered structure in ternary eutectic Mg–Ni–Y alloy

We employ a ternary eutectic Mg_76.87Ni_12.78Y_10.35 alloy to achieve a fine eutectic structure with long-period stacking ordered (LPSO) structure, and investigate the corresponding hydrogen storage behavior. The as-cast Mg_76.87Ni_12.78Y_10.35 alloy is composed of Mg₁₅NiY, Mg₂Ni, MgNi₄Y and Mg phases. A high density of stacking faults and 14H-type LPSO structures form in the Mg₁₅NiY phase. This fine ternary eutectic structure has shown significant improvement in promotion of the activation and following hydrogen absorption kinetics compared with as-cast non-eutectic structure. Pressure-Composition-Temperature (PCT) curves demonstrate two major pressure platforms due to the presence of Mg₁₅NiY and Mg₂Ni in our Mg–Ni–Y alloys. Nanosized Mg₂NiH_x, MgH₂ and YH_x are in situ generated from the decomposition of LPSO structure during hydrogenation. The fine ternary eutectic structure and dispersed nanocatalysts from decomposition of LPSO structure synergistically facilitate the activation and hydrogen absorption kinetics of ternary eutectic Mg–Ni–Y alloy.