New approach to achieve extremely high thermal conductivity of a powder extruded Al–50Si alloy

The Al–50Si alloy, designed for effective heat dissipation in electronic components, was subjected to a two-stage heat treatment process to optimize its microstructure and achieve high thermal conductivity (TC). Two distinct temperature stages were strategically chosen: 850 °C and 550 °C, respectively, with the former operating above and the latter below the eutectic point. The first stage at 850 °C led to the isolation of independent Si particles, each closely associated with individual Al crystal with grain size of approximately 1 mm. Subsequent heat treatment at 550 °C skillfully eliminated introduced eutectic Si through Ostwald ripening. Consequently, the impediments posed by grain boundaries to the movement of electrons and phonons were significantly reduced, yielding an exceptionally high TC of approximately 180 Wm⁻¹K⁻¹, closely approaching the theoretical TC value (∼193 Wm⁻¹K⁻¹) for the Al–50Si alloy. This work paved a new path for the design of outstanding thermal properties in Al–Si electronic packaging materials.