Effect of Silicon Micro-Alloying on the Thermal Conductivity, Mechanical Properties and Rheological Properties of the Al–5Ni Cast Alloy

The near-eutectic aluminum–nickel alloys are promising to be used for thermal management purpose because of their excellent thermal conductivity. However, owing to the solid solubility of nickel in aluminum lattice is small, the mechanical properties of these alloys can barely be promoted via the solid solution strengthening effect. The present study investigates the trace addition of silicon on the microstructure, rheology property, mechanical performance and thermal conductivity of the Al–5Ni alloy. Results show that the α-Al grains in the Al–5Ni alloy with trace silicon are significantly refined, and the fibrous Al₃Ni phase is notably modified. It leads to a remarkable improvement of its mechanical properties. However, the mechanical properties and thermal conductivity are prominently decreased when the dosage of silicon excesses 0.3 wt%. The molten Al–5Ni alloy with relatively high silicon content possesses wider temperature range for flowing, indicating a sound fluidity of the melts, which is related to the solidification routes of the samples. This work provides a reference for the design of cast aluminum alloys with high strength and excellent thermal conductivity.