Microstructure and hydrogen storage properties of the Mg2-xYxNi0.9Co0.1 (x = 0, 0.2, 0.3, and 0.4) alloys

Defa Li; Feng Huang; Bingzhi Ren; Shujie Wang; Wei Zhang; Liming Zhu

doi:10.1038/s41598-024-51602-w

Microstructure and hydrogen storage properties of the Mg_2-xY_xNi_0.9Co_0.1 (x = 0, 0.2, 0.3, and 0.4) alloys

Sci Rep. 2024 Jan 9;14(1):905. doi: 10.1038/s41598-024-51602-w.

Authors

Defa Li¹, Feng Huang², Bingzhi Ren³, Shujie Wang⁴, Wei Zhang¹, Liming Zhu⁵

Affiliations

¹ School of Mechanical and Vehicle Engineering, West Anhui University, Luan, 237012, China.
² Hubei Key Laboratory of Advanced Technology for Automotive Components, Wuhan University of Technology, Wuhan, 430070, China. 303_Lee@163.com.
³ School of Metallurgy and Materials Engineering, Chongqing University of Science and Technology, Chongqing, 401331, China.
⁴ The 13th Research Institute, CETC, Shijiazhuang, 050051, China.
⁵ Hubei Key Laboratory of Advanced Technology for Automotive Components, Wuhan University of Technology, Wuhan, 430070, China.

Abstract

Rare earth elements have excellent catalytic effects on improving hydrogen storage properties of the Mg₂Ni-based alloys. This study used a small amount of Y to substitute Mg partially in Mg₂Ni_0.9Co_0.1 and characterized and discussed the effects of Y on the solidification and de-/hydrogenation behaviors. The Mg_2-xY_xNi_0.9Co_0.1 (x = 0, 0.2, 0.3, and 0.4) hydrogen storage alloys were prepared using a metallurgy method. The phase composition of the alloys was studied using X-ray diffraction (XRD). Additionally, their microstructure and chemical composition were studied using scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. The hydrogen absorption and desorption properties of the alloys were studied using pressure-composition isotherms and differential scanning calorimetric (DSC) measurements. The structure of the as-cast Mg₂Ni_0.9Co_0.1 alloy was composed of the peritectic Mg₂Ni, eutectic Mg-Mg₂Ni, and a small amount of pre-precipitated Mg-Ni-Co ternary phases, and was converted into the Mg₂NiH₄, Mg₂Ni_0.9Co_0.1H₄, and MgH₂ phases after hydrogen absorption. Furthermore, the XRD patterns of the alloys showed the MgYNi₄ phase and a trace amount of the Y₂O₃ phase along with the Mg and Mg₂Ni phases after the addition of Y. After hydrogen absorption, the phase of the alloys was composed of the Mg₂NiH₄, MgH₂, MgYNi₄, YH₃, Y₂O₃, and Mg₂NiH_0.3 phases. With the increase of Y addition, the area ratios of the peritectic Mg₂Ni matrix phase in the Mg_2-xY_xNi_0.9Co_0.1 (x = 0, 0.2, 0.3, and 0.4) alloys gradually decreased until they disappeared. However, the eutectic structure gradually increased, and the microstructures of the alloys were obviously refined. The addition of Y improves the activation performance of the alloys. The alloy only needed one cycle of de-/hydrogenation to complete the activation for x = 0.4. The DSC curves showed that the initial dehydrogenation temperatures of Mg₂Ni_0.9Co_0.1 and Mg_1.8Y_0.2Ni_0.9Co_0.1 were 200 and 156 °C, respectively. The desorption activation energies of the hydrides of the Mg₂Ni_0.9Co_0.1 and Mg_1.8Y_0.2Ni_0.9Co_0.1 alloys calculated using the Kissinger method were 94.7 and 56.5 kJ/mol, respectively. Moreover, the addition of Y reduced the initial desorption temperature of the alloys and improved their kinetic properties.

Abstract

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