Recycling cupola slag for manufacturing magnesium metal matrix composites with alumina for electric vehicle battery pack system housings

This study investigated magnesium matrix composites reinforced with cupola slag (a source of CaSiO₃) and Al₂O₃ particles for potential application in battery pack system (BPS) housings. The composites were fabricated via powder metallurgy, resulting in four systems: a pure magnesium system (100 M), a composite with 85 wt% Mg and 15 wt% cupola slag (85M-15C), and two hybrid composites with 85 wt% Mg combined with 12.5 wt% and 5 wt% cupola slag, and 2.5 wt% and 5 wt% Al₂O₃, respectively, forming the 85M-12.5C-2.5 A and 85M-10C-5A systems. Their mechanical properties and corrosion resistance in a 3.5 wt% NaCl solution were systematically evaluated. Microstructural analysis revealed a significant grain size reduction in the reinforced systems, with the 85M-12.5C-2.5 A system achieving an average grain size of 9.4 µm compared to 22.5 µm in the unreinforced 100 M system. The incorporation of CaSiO₃ and Al₂O₃ reinforcements improved microhardness by up to 55 % and increased compressive strength to a maximum of 329.13 MPa. These enhancements were attributed to grain size and the synergistic effects of micro- and nano-reinforcements. Additionally, the reinforced composites demonstrated superior corrosion resistance, as evidenced by reduced degradation rates in the NaCl solution. This improvement was attributed to the formation of protective Mg(OH)₂ layers, with the 85M-10C-5A system exhibiting the lowest corrosion current density (122 μA/cm²). These findings underscore the potential of magnesium matrix composites reinforced with cupola slag and Al₂O₃ as lightweight, durable, and sustainable materials for BPS housings, addressing both performance and environmental considerations.