Interfacial Al?Ce?Cu?W amorphous layers formed through thermally driven solid-state amorphization within the (W+CeO2)/2024Al composite were investigated. The elemental distributions and interfacial microstructures were examined with an electron probe microanalyzer and a high-resolution transmission electron microscope, respectively. The consolidation of composites consisted of two thermal processes: vacuum degassing (VD) and hot isostatic pressing (HIP). During consolidation, not only the three major elements (Al, W, and Ce) but also the alloying elements (Mg and Cu) in the Al matrix contributed to amorphization. At VD and HIP temperatures of 723 K and 763 K, interfacial amorphous layers were formed within the composite. Three diffusion processes were necessary for interfacial amorphization:(a) long-range diffusion of Mg from the Al matrix to the interfaces during VD; (b) long-range diffusion of Cu from the Al matrix to the inter-faces during HIP; (c) short-range diffusion of W toward the Al matrix during HIP. The newly formed interfacial Al?Ce?Cu?W amorphous layers can be categorized under the Al?Ce?TM (TM: transition metals) amorphous system.