Mechanical Properties and Synthesis of Nanocrystalline Ta - 1.67Al₂O₃ Composite by Pulsed Current Activated Heating

Mixtures of Ta₂O₅ and Al nanopowders were prepared using high energy ball milling method. Nanocrystalline Ta - 1.67Al₂O₃ composite was simultaneously synthesized and densified by pulsed current activated combustion synthesis method in a short time from mechanically activated mixtures of Ta₂O₅ and Al powders. The relative density of the Ta - 1.67Al₂O₃ composites was 98%. The average grain sizes of Ta and Al₂O₃ in the Ta - 1.67Al₂O₃ composite heated up to 1520 °C were determined as 205 and 40 nm, respectively. A Vickers diamond indentation technique were used to evaluate the hardness and fracture toughness of the Ta - 1.67Al₂O₃ composite under applied load 20kg_f. The average Vickers hardness and fracture toughness value were 1340 kg/mm² and 7.9 MPa·m^1/2, respectively.