Optimizing ball milling parameters for controlling the internal microstructure and tensile characteristics of a laminated carbon nanotube/aluminum-copper-magnesium composite

This research investigates how different ball milling conditions influence the microstructure and mechanical properties of carbon nanotube/aluminum alloys. The study examines varying rotation speeds, specifically 200, 300, and 400 rpm. The results highlight the significant impact of milling conditions on grain size and mechanical properties. Notably, milling at 300 rpm /4 h and at 400 rpm/2 h led to higher tensile strength but lower uniform elongation compared to milling at 200 rpm/6 h. The alloy milled at 300 rpm/4 h displayed a refined microstructure, increased density, and the strongest fiber texture along the (111) direction. At 300 rpm/4 h, the presence of a moderate grain size promoted ductility, resulting in the highest uniform elongation (∼9.1%) combined with high strength (∼515 MPa). This in turn means an increase in UTS by 23% and uniform elongation by 3.4% compared to 400 rpm/2 h. The formation of MgAl2O4 at higher rotational speeds positively influences the CNT–Al interface by alleviating the adverse effects of interfacial oxide (Al2O3), resulting in improved bonding and, consequently, enhanced tensile properties. This study provides valuable insights into the effects of ball milling on the microstructure and mechanical properties of metals and alloys, contributing to the optimization of milling conditions to achieve desired material characteristics.