An article of manufacture comprises a carbon-containing matrix. The carbon-containing matrix may comprise at least one type of carbon material selected from the group comprising graphite crystalline carbon materials, carbon powder, and artificial graphite powder. In addition, the carbon-containing matrix comprises a plurality of pores. The article of manufacture also comprises a metal component comprising Al, alloys of Al, or combinations thereof. The metal component is disposed in at least a portion of the plurality of pores. Further, the article of manufacture comprises an additive comprising at least Si. At least a portion of the additive is disposed in an interface between the metal component within the pores and the carbon-containing matrix. The additive enhances phonon coupling and propagation at the interface.