Abstract:Small amounts of nanocrystalline Al₂O₃ particles were doped in WC-Co nanocrystalline powders to study their reinforcing effects, and spark plasma sintering technique was used to fabricate the WC-Co- Al₂O₃ nanocomposites. Experimental results show that the use of Al₂O₃ nanoparticles as dispersions to reinforce WC-Co composites can increase the hardness, especially the transverse rupture strength of the WC-Co hardmetal. With addition of 0.5%(mass fraction) Al₂O₃ nanoparticles, the spark plasma sintered WC-7Co-0.5 Al₂O₃ nanocomposites exhibit hardness of 21.22GPa and transverse rupture strength of 3548MPa. The fracture surface of the WC-7Co-0.5 Al₂O₃ nanocomposites mainly fracture with transcrystalline rupture mode. The reinforcing mechanism is maybe related to the hindrance effect of microcracks propagation and the pinning effect for the dislocations movement, as well as the residual compressive strength due to the Al₂O₃ nanoparticles doped. 

Key words: nanocomposites; WC-Co- Al₂O₃; mechanical properties; spark plasma sintering