Effect of the heat treatment prior to extrusion on the direct hot-extrusion of aluminium powder compacts

Powder compacts from a premixed commercial aluminium powder Al–4.5Cu–0.5Mg–0.2Si (wt%) grade have been densified by direct hot-extrusion. The effect of the heat treatment prior to extrusion on the microstructural evolution of the extruded compacts has been investigated by means of light optical microscopy (LOM), scanning electron microscopy (SEM), and electron backscattered diffraction (EBSD). The interdiffusion of chemical species has demonstrated to have a pronounced influence on the hardening–softening mechanisms taking place during the thermomechanical process. Moreover, the degree of strain attained at different regions (centre and periphery) of the specimens also affects significantly to the mechanisms involved. Grain refinement, intermetallic precipitation, dynamic recovery, and recrystallization have been identified.