Mechanochemical Synthesis and Rapid Consolidation of Nanocrystalline Al2O3-2.25Co Composite by High-Frequency Induction Heating and Its Mechanical Properties

This study focused on synthesizing nanopowders of Co and Al2O3 from Co3O4 and Al powders and fabricating nanocrystalline Al2O3 reinforced Co composite to improve its mechanical properties. Nanopowders of Co and Al2O3 were synthesized from Co3O4 and Al by high-energy ball milling. A highly dense nanostructured 2.25Co-Al2O3 composite was consolidated by high-frequency induction heated sintering method within 3 min from the mechanically synthesized powders (2.25Co Al2O3) under the 80 MPa pressure. The advantage of this process is that it allows for very quick densification to near theoretical density and prohibits grain growth in nanostructured materials. The grain sizes of Co and Al2O3 in the composite were calculated. And the average hardness and fracture toughness values of nanostuctured Co Al2O3 composite were investigated.