Microstructure and Mechanical Properties of Nanostructured Aluminum Consolidated by SPS

Nanostructured aluminum powders were obtained by means of planetary ball milling with methanol as the Process Control Agent (PCA). The behavior, during milling, was considered measuring the microhardness and grain size at different milling times. Bulk near-full density samples were sintered using the Spark Plasma Sintering technology with different schedules: temperature of 500°C and 550°C, pressure of 30 MPa and 60 MPa and different modes of applying the pressure were changed in order to understand the behavior during sintering. The samples sintered at 500°C showed a density of about 2.4-2.61 g/cm3 while for that sintered at 550°C it was 2.65-2.67 g/cm3 depending on the applied pressure. All the samples retained their nanostructure with an increase of the grain size from about 46 up to 70-90 nm. Using X-ray diffraction and metallography the formation of Al4C3 carbides was detected for samples sintered at highest temperatures.