High mechanical performance alumina-reinforced aluminum nanocomposite metal foam produced by powder metallurgy: fabrication, microstructure characterization, and mechanical properties

In this research, alumina-reinforced aluminum nanocomposite foams with high compressive performance were produced using the powder compact melting (PCM) process and CaCO3 foaming agent. The content of Al2O3 nanoparticles, with sizes smaller than 80 nm, varied between 0-15 wt%. Aluminum, Al2O3, and CaCO3 powders were mixed and compacted to dense precursors with 318 MPa stress. Finally, foam samples were fabricated by heating up the precursors at 1000 degrees C for 10 min. A range of porosity values was achieved between 34% to 43% for different combinations of aluminum matrix and alumina reinforcement phase. The crystallite size of the alumina reinforcement phase in Al-3 wt% alumina and Al-15 wt% alumina composite foam was estimated as 23.51 nm and 23.24 nm while the crystallite size of the aluminum matrix was determined as 15.72 nm and 15.44 nm for the same samples. The Field Emission Scanning Electron Microscope (FESEM) images indicated micro-size pores, which were connected via channels. The composite foam with 3 wt% of Al2O3 nanoparticles had a more uniform microstructure and more channels than other samples. The Vickers hardness values of the composites foam increased with an increase in wt% of alumina particles. This amounts to an approximately 93% increase in hardness when 15 wt% alumina particles are added to the aluminum foam. The sample with 3 wt% Al2O3 nanoparticles showed enhanced compressive strain up to 50% with high compressive strength up to 45 MPa and a uniform microstructure.