Spark plasma sintering is a process of rapid, low-temperature, and high-density sintering. Moreover, traditional sintering methods can solve the problems of large grain sizes and low densities. The sintering temperature plays a crucial role in influencing the physical properties of high-silicon–aluminum (Si-Al) composites. This work investigated the impact of temperature on the microstructure, interface, and physical properties of high-Si-Al composites by spark plasma sintering. The results demonstrate that when the powder was processed by ball milling at a sintering temperature of 565 °C, the material exhibited the densest microstructure with minimal pore formation. The average size of the silicon phase is the smallest. The material’s thermal conductivity is 134.6 W/m·K, the thermal expansion coefficient is 8.55 × 10⁻⁶ K⁻¹, the Brinell hardness is 219 HBW, the density is 2.415 g/cm³, and the density reaches 97.75%. An appropriate sintering temperature facilitates particle rearrangement and dissolution–precipitation processes, enhancing the material structure and performance.

SPS (Spark plasma sintering) is characterized by a rapid heating rate, low sintering temperature, and short sintering time, which can effectively suppress the growth of the Si phase during sintering. This study investigated the influence of spark plasma sintering time on the microstructure and properties of high-silicon–aluminum composites. Ball-milled high-silicon–aluminum powder was sintered at 565 °C for different durations. The results showed that the sample sintered for 1 h exhibited the optimal microstructure and properties. Its thermal conductivity, coefficient of thermal expansion, and relative density were 134.6 W/m·K, 8.55 × 10^–6 k^–1, and 97.75%, respectively. Compared with the conventional hot-pressing sintering method, spark plasma sintering requires a shorter sintering time and lower sintering temperature, effectively suppressing the growth of the Si phase, refining the microstructure and improving material performance.