Enhancing thermal and mechanical properties of Al–27Si alloy via powder metallurgy and tailored T6 heat treatment for electronic packaging applications

The Al–27Si alloy was successfully fabricated through cold forming followed by hot pressing sintering at 843 K, achieving high relative density and fine silicon particles, which contribute to outstanding thermal conductivity (TC) and coefficient of thermal expansion (CTE). The microstructure of the alloy was further optimized through a designed heat treatment process consisting of solution treatment at 823 K for 24 h and aging at 453K for 9 h. This treatment led to the dissolution of fine silicon particles and their re-precipitation onto larger silicon particles, reducing the Al–Si interface and α-Al grain boundary density. As a result, the thermal conductivity of the heat-treated Al–27Si alloy increased by ∼8 %, from 173 W m −1 K −1 to 187 W m −1 K −1 , while maintaining superior mechanical properties with a tensile strength of ∼170 MPa and a CTE of ∼14.2 × 10 −6 K −1 at room temperature. Meanwhile, the discontinuously distributed nano-Al 2 O 3 formed at the Al–Si interface after heat treatment effectively suppresses the high-temperature thermal expansion of the Al–27Si alloy. The heat-treated Al–27Si alloy achieves a notable enhancement in TC, while exhibiting a lower CTE at temperatures above 323 K compared to its untreated counterpart.