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

Abstract

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.