Thermal conductivity of short alumina fiber and VGCF hybrid reinforced aluminum alloy composites

In recent years, aluminum alloys have been in high demand in the machinery industry due to their lightweight and energy-saving properties. However, they have the disadvantages of poor high-temperature strength and high thermal expansion. In this study, we aimed to improve the properties of the alloy by using both VGCF, which is expected to enhance thermal conductivity, and alumina short fibers, which are expected to enhance strength, as reinforcing materials. Microstructural observations of the composites revealed that an increase in VGCF volume fraction led to the formation of agglomerated regions and the generation of microporosities. Thermal conductivity of some composites was greater than that of the unreinforced alloy, and the anisotropy in the thermal conductivity of the composites was observed. While the reinforcement with the VGCF and suppression of microporosity enhanced the thermal conductivity of composites, excessive addition of VGCF promoted the formation of the microporosity; it is necessary to select the optimal volume fraction of reinforcing materials.