Microstructure characterization and mechanical properties of bulk nanocrystalline aluminium prepared by SPS and followed by high-temperature extruded techniques

The bulk nc Al was successfully fabricated by SPS and high-temperature extrusion process in this study. Microstructure and mechanical properties of sample were also investigated. Results show that the dislocation densities are 1.847 × 1014 m−2 and 1.673 × 1014 m−2 corresponding to the SPSed and extruded Al, respectively. After SPSed Al was extruded at 450 °C, the grains increased in size by a factor of 2.35 relative to the initial microstructure. Also, the mechanical properties and physical properties of extruded Al are all higher than that of SPSed Al except that SPSed Al has the highest hardness and lower electrical conductivity. The enhancement of mechanical and physical properties of extruded sample is mainly to densification behavior during extruded process.