Effects of Ball Milling Time on Microstructure and Hydrogen Storage Properties of Mg-Cu₉Al₄ Composites

In this paper, Cu₉Al₄, which has no hydrogen storage capacity, was added to magnesium by high energy ball milling to prepare Mg-10 wt.% Cu₉Al₄ composites. The effects of ball milling time on the microstructure and hydrogen storage properties were examined in detail by varying the ball milling time to 60, 120, 180, 240, and 300 min. The findings indicate that increasing the ball milling time reduces particle size and shortens the H atoms' diffusion distance. Moreover, the stabilized (Cu_1.3Al_0.7)Mg phase formed following the initial hydrogenation serves as a nucleation site for Mg/MgH₂ nucleation during the ensuing hydrogen absorption/desorption process, improving the kinetics. According to the testing findings, the Mg-10 wt.% Cu₉Al₄ ball-milled for 240 min has the best hydrogen storage performance, with a reversible hydrogen storage capacity of about 5.73 wt.% and an activation energy for hydrogen desorption of 119.17 kJ/mol.