Study on Microstructure and Hydrogen Storage Properties of Mg80Ni16−xAlxY4 (x = 2, 4, 8) Alloys

Mg80Ni16−xAlxY4 (x = 2, 4, 8) alloys were prepared by induction levitation melting, and the effect of substitution of Al for Ni on the microstructure and hydrogen storage properties was studied in the present work. The results illustrated that the solidification path, phase constitution, and grain size were significantly altered by Al addition. Appropriate Al addition improved abundance and grain refinement of the Mg, Mg2Ni, and Mg15NiY ternary eutectic. But as Al further increased, Mg solidified independently rather than in the formation of the ternary eutectic. More Al favored the formation of Al3Ni2Y but suppressed Mg2Ni and YMgNi4. Although the hydrogen absorption activation and the kinetic property deteriorated, the thermodynamic stability of hydrides was enhanced by adding Al. Hydrogen absorption ability under low pressure was improved, and the Mg80Ni8Al8Y4 alloy could absorb nearly 3.5 wt% hydrogen under 1 bar hydrogen at 250 °C.