The role of Al substitution on the phase evolution in synthesized Mg₂Cu nanoparticles: An insight from X-ray diffraction analysis

In this study, the effect of Mg replacement with Al on the discharge capacity of Mg₂Cu powder mixture is investigated. The mixture of nanocrystalline powder is prepared via mechanical alloying (MA) technique with a high energy planetary ball mill. In addition, different moles of Al are substituted to Mg₂Cu powder (0.05, 0.1, 0.15, 0.2, and 0.3). X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) are used to analyze changes in structure, morphology, and grain size. The obtained powder is utilized as an anode in a nickel-metal hydride battery (Ni-MH). In the specimens with 0.05 M Al content, the orthorhombic structure of Mg₂Cu is emerged after 5 hours milling. The results reveal that more than 0.2 M Al substitution leads to an appearance of MgCu₂ peaks. Al substitution does not affect microstructure uniformity; however, it causes a decrease in crystalline size and lattice parameters. The SAD pattern elucidates that the electrode with the Mg_1.9Al_0.1Cu chemical composition and 20 hours milling has the maximum discharge capacity.