Microstructure evolution and controlled hydrolytic hydrogen generation strategy of Mg-rich Mg-Ni-La ternary alloys

As-cast (Mg-10Ni)_1-x-La_x (x = 0, 5, 10, 15 wt%) ternary Mg-rich alloys with different La contents are successfully prepared by the flux protection melting method. The mechanism of hydrolysis hydrogen generation is investigated in combination with the phase compositions, microstructures, electrochemical properties and hydrolysis hydrogen generation properties. The results show that with the increase of La, the electrochemical activity increase, while the eutectic microstructure decreases. When adding 10 wt% and 15 wt% La, the Mg₁₇La₂ active intermediate phase is observed. In corrosive weak acid medium, the (Mg-10Ni)₉₀La₁₀ (10La) alloy presents the best hydrogen generation performance, while in the neutral distilled water medium, the (Mg-10Ni)₈₅La₁₅ (15La) alloy performs well. The initial hydrolysis reaction kinetics of Mg-Ni-La alloys in distilled water is mainly controlled by the electrochemical activity of the alloy. While, it is mainly determined by the mass transfer channels formed in the microstructures when in weak acid medium. The mechanism of hydrolysis hydrogen generation and the controlled hydrolytic hydrogen generation strategy of Mg-Ni-La alloys proposed in this work provide possible technical guidance to prepare Mg-based hydrogen generation alloys with high reaction activity, high hydrogen generation yield and controlled hydrolysis kinetics.