Microstructure and Hydrogen Absorption/Desorption Behavior of Mg_23-xLa _xNi₁₀ Alloy

Abstract

Induction melting was used as a routine method to synthesize Mg₂₃Ni₁₀, Mg₂₂LaNi₁₀ and Mg₂₁La₂Ni₁₀ alloys, and followed by a detailed microstructural characterization which included X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS), high resolution transmission electron microscope (HRTEM) and hydrogen absorption/desorption measurements. XRD analysis results showed that Mg₂Ni and Mg phases were detected in the XRD pattern of the Mg₂₃Ni₁₀ alloy, however, the La addition results in conversion from Mg to LaMg3 and La2Mg17 phases and appearance of crystal defects included dislocations, twin grain boundary and vacancy in the Mg₂₂LaNi₁₀ and Mg₂₁La₂Ni₁₀ alloy textures. The total maximum hydrogen absorption capacity was 4.45wt% for the Mg₂₃Ni₁₀ alloy, however, the Mg₂₂LaNi₁₀ and Mg₂₁La₂Ni₁₀ alloys with vacancy, dislocations and twin grain boundary, absorbed 3.66wt% and 3.60wt%, respectively, indicating that the La addition led to decreasing of the maximum hydrogen absorption capacity. Besides, hydrogen absorption/desorption of 90% of saturated state expended for about 456 and 990 s for pristine Mg₂₃Ni₁₀ alloy, by contrast, the time decreased owing to improvement of hydrogen absorption and desorption kinetics in the alloy with La element, with which the uptake time for hydrogen content to 90% of saturated state was 150 and 78 s, and 90% hydrogen can be released in 930 and 804 s for Mg₂₂LaNi₁₀ and Mg₂₁La₂Ni₁₀ alloys in the experimental condition.

Keywords

Mg-based alloy / microstructure / hydrogen absorption/desorption behavior

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