Microstructure Characteristics and Hydrogen Storage Kinetics of Mg[sub.77+x]Ni[sub.20−x]La[sub.3] Alloys

• Published in: Materials 2023-06, Vol.16 (13)
• Main Authors: Tian, Hongxiao, Wang, Qichang, Li, Xia, Luo, Long, Li, Yongzhi
• Format: Article
• Language: English
• Subjects: Alloys; Hydrogen as fuel
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma16134576

Mg[sub.77+x]Ni[sub.20−x]La[sub.3] (x = 0, 5, 10, 15) alloys were successfully prepared by the vacuum induction melting method. The structural characterizations of the alloys were performed by using X-ray diffraction and scanning electron microscope. The effects of nickel content on the microstructure and hydrogen storage kinetic of the as-cast alloys were investigated. The results showed that the alloys are composed of a primary phase of Mg[sub.2]Ni, lamella eutectic composites of Mg + Mg[sub.2]Ni, and some amount of LaMg[sub.12] and La[sub.2]Mg[sub.17]. Nickel addition significantly improved the hydrogen-absorption kinetic performance of the alloy. At 683 K, Mg[sub.77]Ni[sub.20]La[sub.3] alloy and Mg[sub.82]Ni[sub.15]La[sub.3] alloy underwent hydrogen absorption and desorption reactions for 2 h, respectively, and their hydrogen absorption and desorption capacities were 4.16 wt.% and 4.1 wt.%, and 4.92 wt.% and 4.69 wt.%, respectively. Using the Kissinger equation, it was calculated that the activation energy values of Mg[sub.77]Ni[sub.20]La[sub.3], Mg[sub.82]Ni[sub.15]La[sub.3], Mg[sub.87]Ni[sub.10]La[sub.3] and Mg[sub.92]Ni[sub.5]La[sub.3] alloys were in the range of 68.5~75.2 kJ/mol, much lower than 150~160 kJ/mol of MgH[sub.2].