Phase structure and hydrogen absorption property of LaMg2Cu

LaMg2Cu alloy was prepared by inductive melting and then was annealed at 723 K for 10 h in 0.1 MPa argon atmospheres. X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed that the alloy consisted of LaMg2Cu2 phase, LaMg3 phase and a few of unknown phases. The annealing treatment improved the equilibrium pressure and hydrogen absorption capacity of LaMg2Cu alloy. The hydrogen absorption capacity of the as-cast and annealed alloys at 473 K were 2.86 and 3.33 wt.%, and the equilibrium pressure were 1 and 3 MPa, respectively. The enthalpy and entropy of LaMg2Cu-H hydriding reaction were determined. LaMg2Cu alloy could absorb hydrogen with rapid hydriding kinetics, the hydrogen absorption rate of LaMg2Cu increased from 423 K to 498 K and the uptake time for hydrogen content to reach 90% of the maximum storage capacity for annealed alloy was less than 550 s at 498 K. The experimental curves of hydrogen absorption kinetics could be fitted with good accuracy by Jander equation. It suggested that the hydriding of LaMg2Cu alloy was a three-dimensional diffusion-controlled process. And the activation energy and pre-exponential factor of LaMg2Cu alloy were also calculated.