Target-Driven Stir Casting for Continuous Networks to Achieve Ultrahigh Thermal Conductivity of Mg-Based Materials

Stir casting processes are utilized primarily to manufacture metal-based materials with random and dispersed reinforcements, thereby enhancing the mechanical properties of alloys. However, continuous network reinforcements are pivotal for high thermal conductivity metal-based materials. To construct the continuous network reinforcements, four stir casting processes on the microstructure and thermal conductivity of the GF (graphite flake)/CF (carbon fiber) Mg (magnesium)-based materials were investigated with the glycerol–water model. The effects of diverse stir casting processes on the construction of the GF/CF continuous network structures followed this order: pre-mixed and laid powder stir casting > semi pre-laid powder stir casting > pre-laid powder stir casting > common stir casting, which is consistent with the order of thermal conductivity. The optimal thermal conductivity of the GF/CF Mg-based materials fabricated by pre-mixed and laid powder stir casting reached 187 W/(m K) with a competitive density of 1.82 g/cm³. The flow and solidification behaviors of the GF/CF were scrutinized for the construction mechanism of the continuous network structure in pre-mixed and laid powder stir casting. The pre-bridging and the disparity in rotational speeds of the GF/CF facilitated the construction of the continuous network structure. The high thermal conductivity GF/CF were readily engulfed by the solid–liquid interface without particle redistribution, which ensured the preservation of the continuous network structure. This research provides valuable insights for manufacturing next-generation high thermal conductivity Mg-based materials utilizing advanced stir casting processes.