In this study. the nano-TiC/AZ61 composites with different heterogeneous bimodal grain (HBG) structures and uniform structure are obtained by regulating the extrusion speed. The effect of HBG structure on the mechanical properties of the composites is investigated. The increasing ductility and toughening mechanism of HBG magnesium matrix composites are carefully discussed. https://www.roneverhart.com/Sigma-Phi-Lambda-Lil-Big-Sister-Tee-Discontinued/